Autobody Surface Coating Manual - Pacific Northwest Pollution

Autobody Surface Coating Manual - Pacific Northwest Pollution
Auto Body
Surface Coating:
A Practical Guide
to Reducing Air
Emissions
Small Business
Pollution Prevention Center
University of Northern Iowa
Auto Body Surface Coating:
A Practical Guide to Reducing Air Emissions
Copyright 1998
Iowa Waste Reduction Center
University of Northern Iowa
Creation of this manual was funded by the U.S. Environmental Protection Agency
under Cooperative Agreement CR 821492-01-4.
Auto Body Surface Coating:
A Practical Guide to Reducing Air Emissions
Copyright 1998
Iowa Waste Reduction Center
University of Northern Iowa
Creation of this manual was funded by the U.S. Environmental Protection Agency
under Cooperative Agreement CR 821492-01-4.
Table of Contents
The following individuals have volunteered to review the manual, Auto Body Surface
Coating: A Practical Guide to Reducing Air Emissions.
Steve Wiedner
Northeast Iowa Community College, Calmar
Jim Phillips
Hawkeye Community College
John Arnold
Arnold’s Body Shop
Carl Sutton
McIntyre Oldsmobile-Cadillac, Inc.
Mark Clark
Clark Supply Corporation
Ron Toyne
Kirkwood Community College
1. Introduction.........................................................................................................1
2. Auto Refinishing Process Overview...................................................................3
A. Recommended Steps for Practical Reduction of Air Emissions.................4
3. Spray Equipment ...............................................................................................7
A. Conventional Air Atomization Spray Equipment.......................................7
Siphon Tube Feed Conventional Spray Guns .............................................8
Gravity Fed Conventional Spray Guns .......................................................9
B. High-Volume / Low-Pressure (HVLP) Turbine ...........................................9
C. High-Volume / Low-Pressure (HVLP) (non-turbine) ................................10
HVLP Spray Guns with Pressure Assist Cup...........................................10
HVLP Gravity Fed Spray Guns .................................................................11
HVLP Siphon Fed Spray Guns ..................................................................11
D. Low-Pressure / Low Volume (LPLV)..........................................................12
E. Recommended Practices for Spray Equipment.........................................12
4. Spray Application Techniques..........................................................................13
A. Recommended Practices for Spray Techniques.........................................17
5. Spray Equipment Cleaning..............................................................................19
A. Manual Cleaning Processes .......................................................................19
B. Pneumatically Powered Mechanical Cleaning Systems...........................20
C. Recommended Practices for Spray Equipment Cleaning.........................21
6. Determining Product VOC Content ................................................................23
7. Surface Prep......................................................................................................25
A. Soap and Water...........................................................................................25
B. Synthetic Reducers....................................................... ..............................25
C. Solvent-Based Cleaners..............................................................................25
D. Waterborne Cleaners .................................................................................26
E. Recommended Practices for Surface Prep.................................................26
8. Undercoats........................................................................................................27
A. Prep Coats...................................................................................................27
Metal Conditioners / Conversion Coatings ...............................................27
Wash-Primers / Vinyl Wash-Primers.........................................................28
Zinc Phosphate Primers .............................................................................28
Self-Etching Primers ..................................................................................29
Epoxy Primers.............................................................................................29
Adhesion Promoters....................................................................................30
Recommended Practices for Prep Coats....................................................30
B. Primer-Surfacers ........................................................................................30
Acrylic Lacquer Primer-Surfacer...............................................................31
Alkyd Synthetic Enamel Primer-Surfacer.................................................31
Self-Etching Primers (as a Primer-Surfacer)............................................31
One-Component Waterborne Primer-Surfacer..........................................32
Table of Contents
The following individuals have volunteered to review the manual, Auto Body Surface
Coating: A Practical Guide to Reducing Air Emissions.
Steve Wiedner
Northeast Iowa Community College, Calmar
Jim Phillips
Hawkeye Community College
John Arnold
Arnold’s Body Shop
Carl Sutton
McIntyre Oldsmobile-Cadillac, Inc.
Mark Clark
Clark Supply Corporation
Ron Toyne
Kirkwood Community College
1. Introduction.........................................................................................................1
2. Auto Refinishing Process Overview...................................................................3
A. Recommended Steps for Practical Reduction of Air Emissions.................4
3. Spray Equipment ...............................................................................................7
A. Conventional Air Atomization Spray Equipment.......................................7
Siphon Tube Feed Conventional Spray Guns .............................................8
Gravity Fed Conventional Spray Guns .......................................................9
B. High-Volume / Low-Pressure (HVLP) Turbine ...........................................9
C. High-Volume / Low-Pressure (HVLP) (non-turbine) ................................10
HVLP Spray Guns with Pressure Assist Cup...........................................10
HVLP Gravity Fed Spray Guns .................................................................11
HVLP Siphon Fed Spray Guns ..................................................................11
D. Low-Pressure / Low Volume (LPLV)..........................................................12
E. Recommended Practices for Spray Equipment.........................................12
4. Spray Application Techniques..........................................................................13
A. Recommended Practices for Spray Techniques.........................................17
5. Spray Equipment Cleaning..............................................................................19
A. Manual Cleaning Processes .......................................................................19
B. Pneumatically Powered Mechanical Cleaning Systems...........................20
C. Recommended Practices for Spray Equipment Cleaning.........................21
6. Determining Product VOC Content ................................................................23
7. Surface Prep......................................................................................................25
A. Soap and Water...........................................................................................25
B. Synthetic Reducers....................................................... ..............................25
C. Solvent-Based Cleaners..............................................................................25
D. Waterborne Cleaners .................................................................................26
E. Recommended Practices for Surface Prep.................................................26
8. Undercoats........................................................................................................27
A. Prep Coats...................................................................................................27
Metal Conditioners / Conversion Coatings ...............................................27
Wash-Primers / Vinyl Wash-Primers.........................................................28
Zinc Phosphate Primers .............................................................................28
Self-Etching Primers ..................................................................................29
Epoxy Primers.............................................................................................29
Adhesion Promoters....................................................................................30
Recommended Practices for Prep Coats....................................................30
B. Primer-Surfacers ........................................................................................30
Acrylic Lacquer Primer-Surfacer...............................................................31
Alkyd Synthetic Enamel Primer-Surfacer.................................................31
Self-Etching Primers (as a Primer-Surfacer)............................................31
One-Component Waterborne Primer-Surfacer..........................................32
Epoxy Primer (as a Primer-Surfacer)........................................................32
Polyester Primer-Surfacer..........................................................................32
Acrylic Urethane Enamel Primer-Surfacer...............................................32
Recommended Practices for Primer-Surfacers .........................................33
C. Primer-Sealers ............................................................................................33
Lacquer Primer-Sealers..............................................................................33
Enamel Type Primer-Sealers......................................................................33
Single Component Waterborne Primer-Surfacer (as a Primer-Sealer)....34
Epoxy Primer (as a Primer-Sealer)............................................................34
Acrylic Urethane Primer-Sealers...............................................................34
Recommended Practices for Primer-Sealers .............................................34
D. Sealers .........................................................................................................35
Tie Coat Sealers..........................................................................................35
Barrier Coat Sealers...................................................................................35
Recommended Practices for Sealers..........................................................35
9. Top Coats ..........................................................................................................37
A. Single Stage Topcoats.................................................................................38
Acrylic Lacquer............................................................................................38
Alkyd Enamel..............................................................................................38
Acrylic Enamel.............................................................................................39
Polyurethane Enamel..................................................................................39
Acrylic Urethane Enamel............................................................................39
B. Two Stage Basecoat / Clearcoat Topcoats .................................................40
Waterborne Basecoat Systems...................................................................40
Advantages of Waterborne Basecoat Systems ..........................................41
Disadvantages of Waterborne Basecoat Systems .....................................42
C. Paint Additives ...........................................................................................42
D. Recommended Practices for Topcoats .......................................................43
10. Recommended Approach to Practical Air Emissions Reduction...................45
11. What to Expect in the Future.........................................................................49
1. Introduction
T
he federal Clean Air Act
Amendments (CAAA) of 1990 are
having a significant impact on small
businesses. New regulations are
being proposed and implemented
that require air emission permits,
and in many cases, expensive air
emission control devices.
These new requirements have had
a tremendous effect on how
automobile surface coating processes
are performed. Specific chemicals
and materials used by the auto body
industry are targeted for regulation
and control. The lists include
chemicals known as Volatile Organic
Compounds (VOCs) and Hazardous
Air Pollutants (HAPs). Both Volatile
Organic Compounds and Hazardous
Air Pollutants are not only harmful
to the environment, but can also
cause severe health problems for
technicians exposed to these
materials.
◆ Volatile Organic Compounds
(VOCs) are considered air
pollutants because they create
unwanted ozone smog in the lower
atmosphere. Many VOCs are also
toxic to humans. Most organic
solvents used in the automotive
painting industry are VOCs and
emissions of these materials have
fallen under new federal air
regulations.
◆ Hazardous Air Pollutants
(HAPs) are 189 materials listed by
the Environmental Protection
Agency (EPA), many of which are
solvents used in surface coating
operations. HAPs include toluene,
xylene, and methyl ethyl ketone.
Eventually, all HAP emissions will
be subject to rigid standards and
strict controls.
The EPA has estimated that the
automobile refinishing industry
alone is responsible for over 287,000
tons of VOCs released in the U.S.
every year. As much as 20 lbs
of organic solvents may be emitted
during the surface coating of just one
medium-sized automobile.
The Clean Air Act
Amendments of
1990 are significantly impacting
small businesses
Control systems have been
developed to help combat VOC
emissions from surface coating
operations. Many manufacturing
firms are currently using these
systems in their paint booths to
reduce VOC emissions by as much as
95 percent. These add-on controls
include: Carbon Adsorption, Thermal
Incineration, Catalytic Incineration,
and Condensers.
Although proven effective in the
manufacturing industry, emission
control systems are extremely
expensive, ranging from $20,000 to
$70,000. For this reason, they are
considered impractical for use in
controlling VOCs from small- to
medium-sized auto body repair
shops. Currently the only practical
means of reducing the VOCs emitted
from automobile refinishing
operations is to reduce the volume of
VOCs and HAPs being used. This
requires changes in products,
equipment and application
techniques for auto refinishers.
VOCs and
HAPs
Emission Reduction for Auto Body Shops
1
Epoxy Primer (as a Primer-Surfacer)........................................................32
Polyester Primer-Surfacer..........................................................................32
Acrylic Urethane Enamel Primer-Surfacer...............................................32
Recommended Practices for Primer-Surfacers .........................................33
C. Primer-Sealers ............................................................................................33
Lacquer Primer-Sealers..............................................................................33
Enamel Type Primer-Sealers......................................................................33
Single Component Waterborne Primer-Surfacer (as a Primer-Sealer)....34
Epoxy Primer (as a Primer-Sealer)............................................................34
Acrylic Urethane Primer-Sealers...............................................................34
Recommended Practices for Primer-Sealers .............................................34
D. Sealers .........................................................................................................35
Tie Coat Sealers..........................................................................................35
Barrier Coat Sealers...................................................................................35
Recommended Practices for Sealers..........................................................35
9. Top Coats ..........................................................................................................37
A. Single Stage Topcoats.................................................................................38
Acrylic Lacquer............................................................................................38
Alkyd Enamel..............................................................................................38
Acrylic Enamel.............................................................................................39
Polyurethane Enamel..................................................................................39
Acrylic Urethane Enamel............................................................................39
B. Two Stage Basecoat / Clearcoat Topcoats .................................................40
Waterborne Basecoat Systems...................................................................40
Advantages of Waterborne Basecoat Systems ..........................................41
Disadvantages of Waterborne Basecoat Systems .....................................42
C. Paint Additives ...........................................................................................42
D. Recommended Practices for Topcoats .......................................................43
10. Recommended Approach to Practical Air Emissions Reduction...................45
11. What to Expect in the Future.........................................................................49
1. Introduction
T
he federal Clean Air Act
Amendments (CAAA) of 1990 are
having a significant impact on small
businesses. New regulations are
being proposed and implemented
that require air emission permits,
and in many cases, expensive air
emission control devices.
These new requirements have had
a tremendous effect on how
automobile surface coating processes
are performed. Specific chemicals
and materials used by the auto body
industry are targeted for regulation
and control. The lists include
chemicals known as Volatile Organic
Compounds (VOCs) and Hazardous
Air Pollutants (HAPs). Both Volatile
Organic Compounds and Hazardous
Air Pollutants are not only harmful
to the environment, but can also
cause severe health problems for
technicians exposed to these
materials.
◆ Volatile Organic Compounds
(VOCs) are considered air
pollutants because they create
unwanted ozone smog in the lower
atmosphere. Many VOCs are also
toxic to humans. Most organic
solvents used in the automotive
painting industry are VOCs and
emissions of these materials have
fallen under new federal air
regulations.
◆ Hazardous Air Pollutants
(HAPs) are 189 materials listed by
the Environmental Protection
Agency (EPA), many of which are
solvents used in surface coating
operations. HAPs include toluene,
xylene, and methyl ethyl ketone.
Eventually, all HAP emissions will
be subject to rigid standards and
strict controls.
The EPA has estimated that the
automobile refinishing industry
alone is responsible for over 287,000
tons of VOCs released in the U.S.
every year. As much as 20 lbs
of organic solvents may be emitted
during the surface coating of just one
medium-sized automobile.
The Clean Air Act
Amendments of
1990 are significantly impacting
small businesses
Control systems have been
developed to help combat VOC
emissions from surface coating
operations. Many manufacturing
firms are currently using these
systems in their paint booths to
reduce VOC emissions by as much as
95 percent. These add-on controls
include: Carbon Adsorption, Thermal
Incineration, Catalytic Incineration,
and Condensers.
Although proven effective in the
manufacturing industry, emission
control systems are extremely
expensive, ranging from $20,000 to
$70,000. For this reason, they are
considered impractical for use in
controlling VOCs from small- to
medium-sized auto body repair
shops. Currently the only practical
means of reducing the VOCs emitted
from automobile refinishing
operations is to reduce the volume of
VOCs and HAPs being used. This
requires changes in products,
equipment and application
techniques for auto refinishers.
VOCs and
HAPs
Emission Reduction for Auto Body Shops
1
1: Introduction
This practical pollution prevention guide was developed to help
automotive refinishers:
• Reduce the amount of VOCs and HAPs emitted during painting
operations
• Avoid the need for expensive ($20,000 - $70,000) emission control
devices
• Decrease the amount of paint-related wastes generated
• Maintain a high quality finish
In essence, "how to do more with less" in surface coating processes.
This Guide provides:
• An overview of the auto refinishing process (Section 2)
• A review of the spray equipment currently used for auto
refinishing operations (Section 3)
• An outline of proper spray application processes (Section 4)
• A look at spray equipment cleaning (purging) processes (Section 5)
• Information on determining products’ VOC content (Section 6)
• A review of surface prep cleaners (Section 7)
• An overview of undercoats (Section 8)
• A look at automotive topcoat systems (Section 9)
• Recommended approach to practical air emission reduction (Section 10)
• A projection of what to expect in the future (Section 11)
2. Auto Refinishing
Process Overview
T
Surface Prep (8%)
Undercoats (17%)
he basic steps in automotive
refinishing include:
1. Prepaint surface cleaning:
Solvents are used for the removal of
contaminants such as grease, tar, wax,
and silicone, all of which can have an
adverse effect on the bond between the
coating and the substrate. Poorly
cleaned surfaces result in finish
imperfections or even the peeling of
the topcoat from the substrate.
Although these solvents are not
typically atomized for application
purposes, VOCs are released through
the simple evaporation of the liquid
solvents. Many of the solvents used for
prepaint surface cleaning contain
toluene and xylene. Each is listed as a
VOC and HAP. In fact, most of these
cleaners contain 75 to 100 percent
VOCs. EPA studies indicate the
evaporation of these solvents accounts
for approximately 8 percent of the total
VOC emissions released during the
refinishing process (see Figure 2).
Equipment
Cleaning (20%)
Topcoats (55%)
Figure 2: EPA Estimates of VOC Emissions
3. Application of the topcoat:
More than half of the VOCs
released during the refinishing
process occur during the top coat
application, with metallics and
lacquer finishes releasing the highest
volume. As with undercoats, the
primary reason for the high release of
VOCs in topcoat application is the
poor transfer efficiency of traditional
spray equipment. Less than one-half
of the topcoat material will be applied
to the desired surface using conventional spray equipment. The rest is
expelled as overspray.
Over half the VOCs
released during the
refinishing process
are from top coat
application
2. Undercoat application:
2
Emission Reduction for Auto Body Shops
The application of undercoats (prep
coats, primer-surfacers, primer-sealers,
and sealers) contributes significantly
to the volume of VOCs released
during surface coating operations.
Undercoats generally contain less
than 50 percent solvents by volume.
However, because of the poor transfer
efficiency of the equipment and the
number of coats typically applied,
solvent based undercoats are
responsible for about 17 percent of all
VOCs released during surface
coating applications.
4. Spray equipment cleaning
operations:
Approximately 20 percent of VOCs
released from auto refinishing occurs
during equipment cleaning
operations. This figure reflects the
volume of organic solvents emitted to
the atmosphere during conventional
equipment cleaning (purging)
procedures. The majority of
commercial spray equipment cleaners
found on the market today are made
entirely of organic solvents.
Emission Reduction for Auto Body Shops
3
1: Introduction
This practical pollution prevention guide was developed to help
automotive refinishers:
• Reduce the amount of VOCs and HAPs emitted during painting
operations
• Avoid the need for expensive ($20,000 - $70,000) emission control
devices
• Decrease the amount of paint-related wastes generated
• Maintain a high quality finish
In essence, "how to do more with less" in surface coating processes.
This Guide provides:
• An overview of the auto refinishing process (Section 2)
• A review of the spray equipment currently used for auto
refinishing operations (Section 3)
• An outline of proper spray application processes (Section 4)
• A look at spray equipment cleaning (purging) processes (Section 5)
• Information on determining products’ VOC content (Section 6)
• A review of surface prep cleaners (Section 7)
• An overview of undercoats (Section 8)
• A look at automotive topcoat systems (Section 9)
• Recommended approach to practical air emission reduction (Section 10)
• A projection of what to expect in the future (Section 11)
2. Auto Refinishing
Process Overview
T
Surface Prep (8%)
Undercoats (17%)
he basic steps in automotive
refinishing include:
1. Prepaint surface cleaning:
Solvents are used for the removal of
contaminants such as grease, tar, wax,
and silicone, all of which can have an
adverse effect on the bond between the
coating and the substrate. Poorly
cleaned surfaces result in finish
imperfections or even the peeling of
the topcoat from the substrate.
Although these solvents are not
typically atomized for application
purposes, VOCs are released through
the simple evaporation of the liquid
solvents. Many of the solvents used for
prepaint surface cleaning contain
toluene and xylene. Each is listed as a
VOC and HAP. In fact, most of these
cleaners contain 75 to 100 percent
VOCs. EPA studies indicate the
evaporation of these solvents accounts
for approximately 8 percent of the total
VOC emissions released during the
refinishing process (see Figure 2).
Equipment
Cleaning (20%)
Topcoats (55%)
Figure 2: EPA Estimates of VOC Emissions
3. Application of the topcoat:
More than half of the VOCs
released during the refinishing
process occur during the top coat
application, with metallics and
lacquer finishes releasing the highest
volume. As with undercoats, the
primary reason for the high release of
VOCs in topcoat application is the
poor transfer efficiency of traditional
spray equipment. Less than one-half
of the topcoat material will be applied
to the desired surface using conventional spray equipment. The rest is
expelled as overspray.
Over half the VOCs
released during the
refinishing process
are from top coat
application
2. Undercoat application:
2
Emission Reduction for Auto Body Shops
The application of undercoats (prep
coats, primer-surfacers, primer-sealers,
and sealers) contributes significantly
to the volume of VOCs released
during surface coating operations.
Undercoats generally contain less
than 50 percent solvents by volume.
However, because of the poor transfer
efficiency of the equipment and the
number of coats typically applied,
solvent based undercoats are
responsible for about 17 percent of all
VOCs released during surface
coating applications.
4. Spray equipment cleaning
operations:
Approximately 20 percent of VOCs
released from auto refinishing occurs
during equipment cleaning
operations. This figure reflects the
volume of organic solvents emitted to
the atmosphere during conventional
equipment cleaning (purging)
procedures. The majority of
commercial spray equipment cleaners
found on the market today are made
entirely of organic solvents.
Emission Reduction for Auto Body Shops
3
2: Auto Refinishing Process Overview
A. Recommended Steps for Practical
Reduction of Air Emissions:
EQUIPMENT CLEANING
• Use an air powered mechanical gun cleaning system.
• Use low VOC cleaning solvents.
SPRAY EQUIPMENT
• If the guns are to be cleaned manually, spray into an enclosed backdrop to capture
atomized solvents.
• Determine the types of coatings that will be sprayed through the equipment, and
the atomization properties required for proper application of these coatings.
• Prior to purchasing any paint gun, consult your paint representative to determine
what type of gun works best for the application of the product you will be using.
• Contact your paint representative and/or spray gun representative to determine
the fluid tip/air cap combination and gun settings recommended for the materials
being sprayed.
• Choose spray equipment that will achieve the highest transfer efficiency while
providing the required atomization properties within your price range.
SPRA Y APPLICATION PRACTICES
• Select the suggested air pressure and tip sizes for the specific product and
equipment being used.
• Always hold the gun perpendicular to the surface being sprayed, using parallel
strokes. Never arc the gun.
• Feather the trigger at the beginning and end of each pass.
See Section 4
for Spray
Application
Practices
Recommended Steps, con’t
To reduce VOCs released during refinishing operations, facilities should
use the following recommended steps for practical air emission reduction:
• Determine the price range you are willing to spend for spray equipment.
See Section 3
for Spray
Equipment
2: Auto Refinishing Process Overview
• Use a 50 percent overlap for each pass. (Note: This technique may need to be
altered slightly when applying high metallic, high solids basecoats, and some
three stage systems.)
• When painting small and medium sized panels, make each pass the full length of
the panel.
• With larger panels, use a comfortable stroke, with a 4 - 5 " overlap of the strokes.
• If blending is necessary, keep the blend area as small as possible without
jeopardizing the appearance of the blend.
• Spray the border edges of the substrate first (banding). This will assure all edges
are covered without extending the spray pattern well beyond the borders of the
object.
• Use color hiding power labels to determine the thickness of the applied paint film.
These markers will also indicate when adequate coverage has been achieved.
See Section 5 for
Equipment Cleaning
• Use a broom straw, cleaning broach, or a soft wood toothpick to clear
passageways.
SURFACE PREP
• Always wash dirt and grime from the vehicle using water or a soap and water
mixture.
• Use waterborne cleaners when possible.
• If, due to heavy contamination, waterborne cleaners prove unsatisfactory, use
solvent based cleaners for the initial cleaning. For secondary cleaning operations,
use the waterborne products.
• If waterborne cleaners prove unsatisfactory due to substrate make-up, use
solvent based cleaners sparingly.
• Keep solvent laden dirty rags in a closed container.
• Keep solvent containers closed when not in use.
See Section 7 for
Surface Prep
• Avoid operations that require multiple prepaint surface cleanings.
PREP COATS
• Use versatile products such as epoxy primers or self-etching primers. The use of
these products may alleviate the need for additional surface coating operations
such as primer-surfacing or primer-sealing.
• If a self-etching primer or epoxy primer is not desirable, use a wash-primer, or
metal conditioner, conversion coating system.
• Avoid zinc-phosphate primers with high VOC content.
See Section 8.A for
Prep Coat
PRIMER-SURFACERS
• Use a properly operating primer gun with the correct fluid tip/air cap combination
for your particular type of primer-surfacer.
• Use low VOC waterborne primer-surfacer products.
• If the curing time of waterborne products proves unsatisfactory, consider the use
of versatile urethane primers.
• To reduce VOC emissions, limit material costs, and achieve a better quality
product, perform body work using a minimal amount of primer-surfacer.
• If a colored sealer is not used, make sure the primer-surfacer is a color that can
easily be covered with the desired topcoat.
See Section 8.B for
Primer-Surfacers
4
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
5
2: Auto Refinishing Process Overview
A. Recommended Steps for Practical
Reduction of Air Emissions:
EQUIPMENT CLEANING
• Use an air powered mechanical gun cleaning system.
• Use low VOC cleaning solvents.
SPRAY EQUIPMENT
• If the guns are to be cleaned manually, spray into an enclosed backdrop to capture
atomized solvents.
• Determine the types of coatings that will be sprayed through the equipment, and
the atomization properties required for proper application of these coatings.
• Prior to purchasing any paint gun, consult your paint representative to determine
what type of gun works best for the application of the product you will be using.
• Contact your paint representative and/or spray gun representative to determine
the fluid tip/air cap combination and gun settings recommended for the materials
being sprayed.
• Choose spray equipment that will achieve the highest transfer efficiency while
providing the required atomization properties within your price range.
SPRA Y APPLICATION PRACTICES
• Select the suggested air pressure and tip sizes for the specific product and
equipment being used.
• Always hold the gun perpendicular to the surface being sprayed, using parallel
strokes. Never arc the gun.
• Feather the trigger at the beginning and end of each pass.
See Section 4
for Spray
Application
Practices
Recommended Steps, con’t
To reduce VOCs released during refinishing operations, facilities should
use the following recommended steps for practical air emission reduction:
• Determine the price range you are willing to spend for spray equipment.
See Section 3
for Spray
Equipment
2: Auto Refinishing Process Overview
• Use a 50 percent overlap for each pass. (Note: This technique may need to be
altered slightly when applying high metallic, high solids basecoats, and some
three stage systems.)
• When painting small and medium sized panels, make each pass the full length of
the panel.
• With larger panels, use a comfortable stroke, with a 4 - 5 " overlap of the strokes.
• If blending is necessary, keep the blend area as small as possible without
jeopardizing the appearance of the blend.
• Spray the border edges of the substrate first (banding). This will assure all edges
are covered without extending the spray pattern well beyond the borders of the
object.
• Use color hiding power labels to determine the thickness of the applied paint film.
These markers will also indicate when adequate coverage has been achieved.
See Section 5 for
Equipment Cleaning
• Use a broom straw, cleaning broach, or a soft wood toothpick to clear
passageways.
SURFACE PREP
• Always wash dirt and grime from the vehicle using water or a soap and water
mixture.
• Use waterborne cleaners when possible.
• If, due to heavy contamination, waterborne cleaners prove unsatisfactory, use
solvent based cleaners for the initial cleaning. For secondary cleaning operations,
use the waterborne products.
• If waterborne cleaners prove unsatisfactory due to substrate make-up, use
solvent based cleaners sparingly.
• Keep solvent laden dirty rags in a closed container.
• Keep solvent containers closed when not in use.
See Section 7 for
Surface Prep
• Avoid operations that require multiple prepaint surface cleanings.
PREP COATS
• Use versatile products such as epoxy primers or self-etching primers. The use of
these products may alleviate the need for additional surface coating operations
such as primer-surfacing or primer-sealing.
• If a self-etching primer or epoxy primer is not desirable, use a wash-primer, or
metal conditioner, conversion coating system.
• Avoid zinc-phosphate primers with high VOC content.
See Section 8.A for
Prep Coat
PRIMER-SURFACERS
• Use a properly operating primer gun with the correct fluid tip/air cap combination
for your particular type of primer-surfacer.
• Use low VOC waterborne primer-surfacer products.
• If the curing time of waterborne products proves unsatisfactory, consider the use
of versatile urethane primers.
• To reduce VOC emissions, limit material costs, and achieve a better quality
product, perform body work using a minimal amount of primer-surfacer.
• If a colored sealer is not used, make sure the primer-surfacer is a color that can
easily be covered with the desired topcoat.
See Section 8.B for
Primer-Surfacers
4
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
5
2: Auto Refinishing Process Overview
Recommended Steps, con’t
3. Spray Equipment
PRIMER-SEALERS
See Section
8.C for
Primer-Sealers
• Use low VOC primer-sealers such as single component waterborne primers or
waterborne epoxy primers.
• Use low VOC urethane primer-sealers as an alternative when possible.
• Always choose a color of primer-sealer that can be easily covered with the topcoat
to be sprayed, or choose a tintable primer-sealer and tint it to an easily covered
shade.
SEALERS
See Section 8.D
for Sealers
• Choose the proper sealer for each specific job.
• If filling capabilities are required, use a primer-sealer in place of a sealer.
• Always choose a primer-sealer of a color that can be easily covered with the
coating to be sprayed, or choose a tintable primer-sealer.
TOPCOATS
See Section 9 for
Topcoats
• Mix color coats in-house, making certain the formula for the proper shade of the
specific color code is used. This will help avoid the need for blending the
finish to achieve a satisfactory color match.
• Keep good records of paint match information, including spray-out cards and
detailed notes.
• Avoid the use of lacquer-based topcoats.
• Choose low VOC topcoats that require fewer than three coats to achieve adequate
coverage (polyurethane or urethane).
• Apply only the number of coats needed to achieve a quality finish.
• Use high solids / low VOC clears to topcoat color coats.
• Keep the use of paint additives to a minimum.
• When available, use waterborne basecoats.
P
rior to the Clean Air Act, most
technicians chose spray
equipment based solely on its ability
to apply a quality finish. As the
focus on VOC emissions within the
refinishing industry continues to
grow, transfer efficiency has become
a major factor in spray equipment
selection.
Simply put, transfer efficiency is
the percentage of material atomized
through the gun that actually ends
up as a coating on the desired
surface. However, the transfer
efficiency of any type of spray
equipment is subject to change under
a variety of conditions. Variables
affecting transfer efficiency include:
• Technician's spraying technique
• Size and configuration of the
object to be sprayed
• Distance of the gun from the object
to be sprayed
• Size of air cap and nozzle used
• Air pressure at the tip
• Volume of material exiting the gun
at the tip
• Volume of air leaving the gun at
the tip
• Viscosity of the material being
sprayed
• Atmospheric conditions
(temperature, humidity and
barometric pressure)
Spray gun manufacturers have
developed several new spray
technologies in an attempt to achieve
optimum efficiency. While achieving
excellent transfer efficiency, many of
these new technologies were found to
be unacceptable for use in the
application of automobile topcoats.
Excess orange peel, pinholing,
solvent popping, and mottling were
common with many of these systems.
Fortunately, a few of these new
technologies proved capable of
producing a high quality finish and
thus are able to compete with
conventional spray equipment in the
refinishing industry. These new
systems include gravity fed conventional, high-volume/low-pressure
turbine, high-volume/low-pressure
non-turbine, and low-pressure/lowvolume spray guns.
Transfer efficiency is
a major factor in
spray equipment
selection
A. Conventional Air
Atomization Spray Equipment
For decades, the conventional
suction feed spray gun has been the
overwhelming favorite of automotive
refinishers worldwide. These
systems provide excellent
atomization of the coating while
giving the operator the control
needed to achieve an even, high gloss
finish. Conventional air guns rely on
high pressure air (35 - 80 psi) to
atomize the coating for application.
This atomization of coatings takes
place in three separate stages.
The conventional
suction feed spray
gun has been the
overwhelming favorite
of auto refinishers
1. The paint is surrounded by a
highly pressurized column of air.
This air column causes turbulence
to occur in the paint, which begins
to separate the paint into small
droplets.
2. The paint is then forced through
the fluid nozzle of the gun. Air is
released through containment
holes in the air cap, enhancing the
atomization of the fluid.
6
7
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
2: Auto Refinishing Process Overview
Recommended Steps, con’t
3. Spray Equipment
PRIMER-SEALERS
See Section
8.C for
Primer-Sealers
• Use low VOC primer-sealers such as single component waterborne primers or
waterborne epoxy primers.
• Use low VOC urethane primer-sealers as an alternative when possible.
• Always choose a color of primer-sealer that can be easily covered with the topcoat
to be sprayed, or choose a tintable primer-sealer and tint it to an easily covered
shade.
SEALERS
See Section 8.D
for Sealers
• Choose the proper sealer for each specific job.
• If filling capabilities are required, use a primer-sealer in place of a sealer.
• Always choose a primer-sealer of a color that can be easily covered with the
coating to be sprayed, or choose a tintable primer-sealer.
TOPCOATS
See Section 9 for
Topcoats
• Mix color coats in-house, making certain the formula for the proper shade of the
specific color code is used. This will help avoid the need for blending the
finish to achieve a satisfactory color match.
• Keep good records of paint match information, including spray-out cards and
detailed notes.
• Avoid the use of lacquer-based topcoats.
• Choose low VOC topcoats that require fewer than three coats to achieve adequate
coverage (polyurethane or urethane).
• Apply only the number of coats needed to achieve a quality finish.
• Use high solids / low VOC clears to topcoat color coats.
• Keep the use of paint additives to a minimum.
• When available, use waterborne basecoats.
P
rior to the Clean Air Act, most
technicians chose spray
equipment based solely on its ability
to apply a quality finish. As the
focus on VOC emissions within the
refinishing industry continues to
grow, transfer efficiency has become
a major factor in spray equipment
selection.
Simply put, transfer efficiency is
the percentage of material atomized
through the gun that actually ends
up as a coating on the desired
surface. However, the transfer
efficiency of any type of spray
equipment is subject to change under
a variety of conditions. Variables
affecting transfer efficiency include:
• Technician's spraying technique
• Size and configuration of the
object to be sprayed
• Distance of the gun from the object
to be sprayed
• Size of air cap and nozzle used
• Air pressure at the tip
• Volume of material exiting the gun
at the tip
• Volume of air leaving the gun at
the tip
• Viscosity of the material being
sprayed
• Atmospheric conditions
(temperature, humidity and
barometric pressure)
Spray gun manufacturers have
developed several new spray
technologies in an attempt to achieve
optimum efficiency. While achieving
excellent transfer efficiency, many of
these new technologies were found to
be unacceptable for use in the
application of automobile topcoats.
Excess orange peel, pinholing,
solvent popping, and mottling were
common with many of these systems.
Fortunately, a few of these new
technologies proved capable of
producing a high quality finish and
thus are able to compete with
conventional spray equipment in the
refinishing industry. These new
systems include gravity fed conventional, high-volume/low-pressure
turbine, high-volume/low-pressure
non-turbine, and low-pressure/lowvolume spray guns.
Transfer efficiency is
a major factor in
spray equipment
selection
A. Conventional Air
Atomization Spray Equipment
For decades, the conventional
suction feed spray gun has been the
overwhelming favorite of automotive
refinishers worldwide. These
systems provide excellent
atomization of the coating while
giving the operator the control
needed to achieve an even, high gloss
finish. Conventional air guns rely on
high pressure air (35 - 80 psi) to
atomize the coating for application.
This atomization of coatings takes
place in three separate stages.
The conventional
suction feed spray
gun has been the
overwhelming favorite
of auto refinishers
1. The paint is surrounded by a
highly pressurized column of air.
This air column causes turbulence
to occur in the paint, which begins
to separate the paint into small
droplets.
2. The paint is then forced through
the fluid nozzle of the gun. Air is
released through containment
holes in the air cap, enhancing the
atomization of the fluid.
6
7
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
3: Spray Equipment
3. Finally, air is released from the
horns of the air cap and comes in
contact with the atomized paint.
This not only helps in the
atomization process, but also
shapes the paint pattern.
HVLP Turb
HVLP
Gravity
Siphon
Figure 3: Transfer Efficiency of Spray Equipment
The sudden release of this high
pressure air through the small
openings of the nozzle breaks up the
paint and propels the spray away
from the gun. The atomized
material is transferred to the
substrate at a high velocity causing
violent air turbulence to occur at the
surface of the substrate. This
turbulence forces much of the
atomized material away from the
surface to be coated, resulting in
more than half of the atomized paint
particulates and solvents being lost
as waste overspray.
Siphon Tube Feed Conventional
Spray Guns
The siphon tube spray gun has
been by far the favorite of auto body
refinishing technicians for both
undercoat and topcoat applications.
This equipment produces a
fully atomized paint
pattern for even surface
coverage and gives the
control needed for the
application of metallic
finishes. The spray
pattern allows even distriLPLV
bution of metallic flakes
throughout the substrate
resulting in a finish free of
metallic mottling flaws.
The simple design of these
guns makes them very
economical to purchase
and maintain. A good
quality siphon tube spray
gun costs from $120 $300.
Depending on the
material sprayed and the
pressure used, the transfer efficiency
of a siphon tube spray gun may be as
low as 35 percent. Sprayable
material is lost through the exhaust
system or as overspray on the booth
floor. Because air pressure is used to
pull the fluid from the cup to gun,
only low viscosity coatings may be
used effectively in these systems.
The higher the material’s viscosity,
the greater the air pressure required
to draw the material up the siphon
tube. The higher the pressure, the
greater the amount of material
wasted as overspray. The siphon
design makes it impossible to
retrieve all the paint from the cup, so
there will always be some unused
material.
3: Spray Equipment
Gravity Fed Conventional Spray
Guns
Gravity fed technology first
became popular with European auto
refinishers for its ability to apply
higher viscosity coatings such as
epoxy primers and high solids paints
and clears. As the use of these
coatings has increased in the U.S., so
has the acceptance of gravity fed
guns within the automobile repair
industry.
The major design difference
between the gravity and siphon fed
designs is the location of the paint
cup. The cup is located on top of the
gravity fed guns, as opposed to the
siphon tube spray guns, which have
the cup located below the body of the
gun. This cup location gives the
gravity fed guns a distinct advantage
in clearance over siphon fed
equipment. This advantage becomes
evident when spraying the lower
panels of today's smaller
automobiles. Gravity fed spray guns
rely on gravity, not air pressure, to
feed the fluid to the gun. Higher
viscosity solutions can be sprayed
and atomized more effectively than
in siphon fed equipment.
Because of cup placement,
virtually all the paint in the cup can
be used with little or no waste. The
majority of these cups are made of a
semi-clear solvent-resistant plastic
which gives the painter the added
advantage of being able to see the
amount of material left in the
reservoir while spraying. The
transfer efficiency of the gravity fed
guns is slightly better due to the
higher viscosity material used,
averaging approximately 40 percent.
Many painters adjust well to the
gravity fed technology and can apply
quality finishes with the first or
second use. Others find adapting to
this type of equipment difficult.
There are four specific obstacles that
must be overcome to use gravity fed
spray guns effectively. First, because
of the gravity fed design of these
guns, as the paint level decreases, so
does the rate of material feed.
Although minor, the operator must
still adjust technique throughout the
coating process to compensate for the
change in fluid flow. Second, some
painters find that the high
positioning of the cup interferes with
the visibility of the surface during
coating applications. Modifications
to a painter's spray technique may
be required to compensate for this
obstruction. Third, difficulties occur
when spraying the underside of body
panels. If the gun is pointed
upwards, the material will not flow
to the gun from the cup. Finally, the
physical design of the equipment
does not allow the operator to set the
gun down without the aid of a stand
or spray gun hanger.
B. High-Volume/Low Pressure (HVLP) Turbine
The HVLP turbine spray guns
have reportedly achieved transfer
efficiencies of 80 to 90 percent,
exceeding all other automotive
refinishing spray equipment on the
market today (see Figure 3, pg 8).
These systems use columns of low
pressure air to cause turbulence
within the paint as the first stage of
atomization. The air used for the
final step of atomization originates
from high-volume turbine driven
blowers. This air is heated to assist
HVLP
Turbine Guns
8
9
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
3: Spray Equipment
3. Finally, air is released from the
horns of the air cap and comes in
contact with the atomized paint.
This not only helps in the
atomization process, but also
shapes the paint pattern.
HVLP Turb
HVLP
Gravity
Siphon
Figure 3: Transfer Efficiency of Spray Equipment
The sudden release of this high
pressure air through the small
openings of the nozzle breaks up the
paint and propels the spray away
from the gun. The atomized
material is transferred to the
substrate at a high velocity causing
violent air turbulence to occur at the
surface of the substrate. This
turbulence forces much of the
atomized material away from the
surface to be coated, resulting in
more than half of the atomized paint
particulates and solvents being lost
as waste overspray.
Siphon Tube Feed Conventional
Spray Guns
The siphon tube spray gun has
been by far the favorite of auto body
refinishing technicians for both
undercoat and topcoat applications.
This equipment produces a
fully atomized paint
pattern for even surface
coverage and gives the
control needed for the
application of metallic
finishes. The spray
pattern allows even distriLPLV
bution of metallic flakes
throughout the substrate
resulting in a finish free of
metallic mottling flaws.
The simple design of these
guns makes them very
economical to purchase
and maintain. A good
quality siphon tube spray
gun costs from $120 $300.
Depending on the
material sprayed and the
pressure used, the transfer efficiency
of a siphon tube spray gun may be as
low as 35 percent. Sprayable
material is lost through the exhaust
system or as overspray on the booth
floor. Because air pressure is used to
pull the fluid from the cup to gun,
only low viscosity coatings may be
used effectively in these systems.
The higher the material’s viscosity,
the greater the air pressure required
to draw the material up the siphon
tube. The higher the pressure, the
greater the amount of material
wasted as overspray. The siphon
design makes it impossible to
retrieve all the paint from the cup, so
there will always be some unused
material.
3: Spray Equipment
Gravity Fed Conventional Spray
Guns
Gravity fed technology first
became popular with European auto
refinishers for its ability to apply
higher viscosity coatings such as
epoxy primers and high solids paints
and clears. As the use of these
coatings has increased in the U.S., so
has the acceptance of gravity fed
guns within the automobile repair
industry.
The major design difference
between the gravity and siphon fed
designs is the location of the paint
cup. The cup is located on top of the
gravity fed guns, as opposed to the
siphon tube spray guns, which have
the cup located below the body of the
gun. This cup location gives the
gravity fed guns a distinct advantage
in clearance over siphon fed
equipment. This advantage becomes
evident when spraying the lower
panels of today's smaller
automobiles. Gravity fed spray guns
rely on gravity, not air pressure, to
feed the fluid to the gun. Higher
viscosity solutions can be sprayed
and atomized more effectively than
in siphon fed equipment.
Because of cup placement,
virtually all the paint in the cup can
be used with little or no waste. The
majority of these cups are made of a
semi-clear solvent-resistant plastic
which gives the painter the added
advantage of being able to see the
amount of material left in the
reservoir while spraying. The
transfer efficiency of the gravity fed
guns is slightly better due to the
higher viscosity material used,
averaging approximately 40 percent.
Many painters adjust well to the
gravity fed technology and can apply
quality finishes with the first or
second use. Others find adapting to
this type of equipment difficult.
There are four specific obstacles that
must be overcome to use gravity fed
spray guns effectively. First, because
of the gravity fed design of these
guns, as the paint level decreases, so
does the rate of material feed.
Although minor, the operator must
still adjust technique throughout the
coating process to compensate for the
change in fluid flow. Second, some
painters find that the high
positioning of the cup interferes with
the visibility of the surface during
coating applications. Modifications
to a painter's spray technique may
be required to compensate for this
obstruction. Third, difficulties occur
when spraying the underside of body
panels. If the gun is pointed
upwards, the material will not flow
to the gun from the cup. Finally, the
physical design of the equipment
does not allow the operator to set the
gun down without the aid of a stand
or spray gun hanger.
B. High-Volume/Low Pressure (HVLP) Turbine
The HVLP turbine spray guns
have reportedly achieved transfer
efficiencies of 80 to 90 percent,
exceeding all other automotive
refinishing spray equipment on the
market today (see Figure 3, pg 8).
These systems use columns of low
pressure air to cause turbulence
within the paint as the first stage of
atomization. The air used for the
final step of atomization originates
from high-volume turbine driven
blowers. This air is heated to assist
HVLP
Turbine Guns
8
9
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
3: Spray Equipment
in the atomization process and is
transferred to the gun using large
diameter air lines. The air is used to
atomize the paint in basically the
same manner as a conventional gun,
but is much more efficient. The
turbine supplies all the air needed
for the system to operate. No outside
air source is required.
HVLP turbine spray guns have some
distinct disadvantages.
• The cost of these systems is high,
with price tags commonly
exceeding $3,000.
• The large air lines are often
cumbersome for the operator.
• Blending metallic finishes is very
difficult using the HVLP system
due to the heavy application coats.
• The atomization of the turbine
HVLP spray guns may not give
the quality finish required to
match automotive factory finishes.
C. High-Volume/LowPressure (HVLP) (non-turbine)
HVLP NonTurbine Guns
The problems of the HVLP turbine
in automotive refinishing were
quickly realized by the spray gun
manufacturers. To help alleviate
some of these downfalls, manufacturers developed more versatile, less
expensive HVLP spray equipment.
Depending on the make of gun, these
systems have a transfer efficiency
ranging from 55 - 75 percent, and
report a savings in material of 20 30 percent over conventional spray
guns. The non-turbine HVLP guns
use only conventional shop air for
their operations. No expensive
auxiliary air supply sources or
turbines are needed. These spray
guns do require high volumes of air
(13 - 30 cfm at 10 psi), so at least a
five horsepower compressor, with
adequate piping (i.e. 3/4") is usually
required to supply the needed volume
of air. As with all non-turbine low
pressure spray equipment, incoming
air must be dry to prevent water
condensation within the gun.
The non-turbine HVLP technology
has proved to be a vast improvement
over the turbine models, but it still
has obstacles that must be overcome.
The application rates of the HVLP
systems are much slower than that
of conventional spray equipment.
Also, non-turbine HVLP spray guns
do not offer the metallic control of
conventional style guns, making the
spraying of metallic topcoats difficult
to master. As with all HVLP spray
equipment, non-turbine models clog
easily. For this reason, coating
material filtration and proper gun
cleaning practices are essential.
Finally, blending topcoats using the
HVLP technology has been a
challenge for painters. The thick
coats applied using the HVLP guns
do not produce the gradual tapering
effect needed for blending of high
solid and metallic topcoats.
HVLP Spray Guns With Pressure
Assist Cup
One attempt to improve the HVLP
technology to better suit the auto
repair industry was the addition of a
pressure cup to the system. These
systems use a paint cup mounted
under the gun, similar to a conventional spray gun design. With this
style, the cup is pressurized, using a
3: Spray Equipment
separate regulated air line, to feed
the paint to the gun. The
pressurized cup improves the
transfer efficiency of the gun.
As with any pressurized paint gun,
care must be taken not to overpressurize the paint cup or remove a
pressurized cup.
Equipment damage or
operator injury may
result. Some atomization
problems may also be
experienced when spraying
epoxy primers and high
solids coatings due to their
high viscosity.
siphon fed spray guns come as close
as any of the HVLP equipment to
looking and feeling like a conventional siphon spray gun. Some
companies are even producing
conversion kits to make a conventional siphon fed into an HVLP
HVLP Gravity Fed Spray
Guns
The gravity fed HVLP
guns (see Figure 4)
combine the finest
qualities of the HVLP and
conventional gravity fed
spray guns into one design.
Like its conventional counterpart,
these guns work especially well on
high solids and water-based paints,
clears, and primers due to their top
mounting, gravity fed material cup.
This design also shares the
disadvantages of its conventional
counterpart; as the paint level
decreases, so does the feed rate.
Therefore, the operator must adjust
technique to compensate for the
change in fluid flow.
Figure 4: HVLP Gravity Fed Spray Gun
siphon feed gun. This makes the
price of this HVLP technology
extremely affordable. These guns
produce basically the same soft spray
pattern as all HVLP guns with
atomizing pressures as low as 5 psi.
The siphon design has a lower
transfer efficiency than other HVLP
technologies.
HVLP Siphon Fed Spray Guns
D. Low-Pressure/Low- Volume
(LPLV)
To gain acceptance in the auto
refinishing industry, some spray gun
manufacturers are producing siphon
fed HVLP spray equipment. The
Another spray technology
developed to improve transfer
efficiency is the Low-Pressure/LowVolume (LPLV) spray equipment.
10
11
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
3: Spray Equipment
in the atomization process and is
transferred to the gun using large
diameter air lines. The air is used to
atomize the paint in basically the
same manner as a conventional gun,
but is much more efficient. The
turbine supplies all the air needed
for the system to operate. No outside
air source is required.
HVLP turbine spray guns have some
distinct disadvantages.
• The cost of these systems is high,
with price tags commonly
exceeding $3,000.
• The large air lines are often
cumbersome for the operator.
• Blending metallic finishes is very
difficult using the HVLP system
due to the heavy application coats.
• The atomization of the turbine
HVLP spray guns may not give
the quality finish required to
match automotive factory finishes.
C. High-Volume/LowPressure (HVLP) (non-turbine)
HVLP NonTurbine Guns
The problems of the HVLP turbine
in automotive refinishing were
quickly realized by the spray gun
manufacturers. To help alleviate
some of these downfalls, manufacturers developed more versatile, less
expensive HVLP spray equipment.
Depending on the make of gun, these
systems have a transfer efficiency
ranging from 55 - 75 percent, and
report a savings in material of 20 30 percent over conventional spray
guns. The non-turbine HVLP guns
use only conventional shop air for
their operations. No expensive
auxiliary air supply sources or
turbines are needed. These spray
guns do require high volumes of air
(13 - 30 cfm at 10 psi), so at least a
five horsepower compressor, with
adequate piping (i.e. 3/4") is usually
required to supply the needed volume
of air. As with all non-turbine low
pressure spray equipment, incoming
air must be dry to prevent water
condensation within the gun.
The non-turbine HVLP technology
has proved to be a vast improvement
over the turbine models, but it still
has obstacles that must be overcome.
The application rates of the HVLP
systems are much slower than that
of conventional spray equipment.
Also, non-turbine HVLP spray guns
do not offer the metallic control of
conventional style guns, making the
spraying of metallic topcoats difficult
to master. As with all HVLP spray
equipment, non-turbine models clog
easily. For this reason, coating
material filtration and proper gun
cleaning practices are essential.
Finally, blending topcoats using the
HVLP technology has been a
challenge for painters. The thick
coats applied using the HVLP guns
do not produce the gradual tapering
effect needed for blending of high
solid and metallic topcoats.
HVLP Spray Guns With Pressure
Assist Cup
One attempt to improve the HVLP
technology to better suit the auto
repair industry was the addition of a
pressure cup to the system. These
systems use a paint cup mounted
under the gun, similar to a conventional spray gun design. With this
style, the cup is pressurized, using a
3: Spray Equipment
separate regulated air line, to feed
the paint to the gun. The
pressurized cup improves the
transfer efficiency of the gun.
As with any pressurized paint gun,
care must be taken not to overpressurize the paint cup or remove a
pressurized cup.
Equipment damage or
operator injury may
result. Some atomization
problems may also be
experienced when spraying
epoxy primers and high
solids coatings due to their
high viscosity.
siphon fed spray guns come as close
as any of the HVLP equipment to
looking and feeling like a conventional siphon spray gun. Some
companies are even producing
conversion kits to make a conventional siphon fed into an HVLP
HVLP Gravity Fed Spray
Guns
The gravity fed HVLP
guns (see Figure 4)
combine the finest
qualities of the HVLP and
conventional gravity fed
spray guns into one design.
Like its conventional counterpart,
these guns work especially well on
high solids and water-based paints,
clears, and primers due to their top
mounting, gravity fed material cup.
This design also shares the
disadvantages of its conventional
counterpart; as the paint level
decreases, so does the feed rate.
Therefore, the operator must adjust
technique to compensate for the
change in fluid flow.
Figure 4: HVLP Gravity Fed Spray Gun
siphon feed gun. This makes the
price of this HVLP technology
extremely affordable. These guns
produce basically the same soft spray
pattern as all HVLP guns with
atomizing pressures as low as 5 psi.
The siphon design has a lower
transfer efficiency than other HVLP
technologies.
HVLP Siphon Fed Spray Guns
D. Low-Pressure/Low- Volume
(LPLV)
To gain acceptance in the auto
refinishing industry, some spray gun
manufacturers are producing siphon
fed HVLP spray equipment. The
Another spray technology
developed to improve transfer
efficiency is the Low-Pressure/LowVolume (LPLV) spray equipment.
10
11
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
3: Spray Equipment
LPLV Guns
Like the HVLP equipment, LPLV
guns use conventional shop air and
do not require expensive turbine
units. The LPLV spray guns require
only 7 - 8 cfm of compressed air at
10 psi (as opposed to the 13 - 30 cfm
required for HVLP equipment).
Unlike HVLP equipment, the first
stage of atomization occurs within
the LPLV spray gun. Air and paint
are mixed inside an internal chamber
of the air cap to further assist in the
paint atomization. The LPLV
systems boast a transfer efficiency
ranging from 55 - 75 percent.
As with all the new spray
technologies, the LPLV systems have
obstacles that the painter must
overcome. Among these is a
pressurized cup, used in some LPLV
systems, which is only pressurized
when the gun trigger is pulled.
Some changes in spray technique
may be required to accommodate
this delay in material delivery.
LPLV spray equipment has gained
only minimal acceptance in the
automobile refinishing industry.
Prior to purchasing any paint
gun, consult your paint representative to determine which type of
gun will work best for the
application of the product you will
use. Your paint and/or spray gun
representative can also help you
determine the proper fluid tip/air
cap combination and proper gun
settings.
E. Recommended Practices for Spray Equipment
•Determine the price range you are willing to spend for spray equipment.
•Determine the types of coatings that will be sprayed through the
equipment and the atomization properties required for their proper
application.
•Choose spray equipment that will achieve the highest transfer efficiency
while providing the required atomization properties within your price
range.
•Prior to purchasing any paint gun, consult your paint representative to
determine what type of gun will work best for the application of the
product you will be using.
•Contact your paint representative and/or spray gun representative to
determine the fluid tip/air cap combination and gun settings that should
be used with the material being sprayed.
4. Spray Application
Techniques
B
oth the quality of the finish and
transfer efficiency greatly depend
on the technician’s skill and spraying
techniques. Cost and sophistication
of paint application equipment do not
ensure a quality finish. In order to
achieve a quality finish, the painter
must focus on the proper combination
of the following variables:
• Type of material to be sprayed
• Viscosity of material
• Thinner/reducer speed used
• Type of hardener or reactor used
• Addition of additives
• Booth air temperature
• Booth air flow
• Paint gun orifice size
• Paint gun air cap style
• Paint gun adjustments (air, fluid,
fan size)
• Distance of the spray gun from
surface
• Operator's spray gun speed
According to a study done by the
Pacific Northwest Pollution
Prevention Research Center,
"Transfer Efficiency and VOC
Emissions of Spray Gun Coating
Technologies in Wood Finishing", the
VOC emissions released during a
surface coating process are directly
related to the skill of the spray gun
operator. The study concluded that
"the difference in transfer efficiency
due to painter skill level with a
single gun type were often larger
than the differences between gun
types." In other words, proper
painting technique is often more
important than high transfer
efficient spray equipment when it
comes to reducing emissions. A
skilled technician will adjust
spraying style with each specific job
to compensate for the type of coating
being sprayed, the atmospheric
conditions, the size and shape of the
object being coated and the spray
equipment used. Due to all the
variables involved, it is impossible to
specify the one best spray technique
for all situations.
The quality of the
finish and transfer
efficiency depend on ht
skill and technique of
the technician
Painting technique is
often more important
than transfer efficient
spray equipment in
reducing emissions
In general, technicians should follow these basic rules.
A. Always have the correct gun setup for the coating to be sprayed and the size of
the area to be covered. These variables include the size of fluid tip and air cap
used. Fluid tip size is determined by the viscosity of the coating as well as the
flow rate setting of the gun. The viscosity is determined using a Zahn cup
measuring system (see figure 5, pg 14).
The flow rate can be determined through the following process:
For pressure fed spray equipment:
1. Turn off the atomizing air.
2. Aim spray gun tip towards a container (preferably a graduated container).
3. Pull the trigger of the gun, spraying the unatomized coating into the container
for 60 seconds.
4. Measure the amount of material expelled from the gun into the container to
determine the flow rate in ounces/minute.
12
13
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
3: Spray Equipment
LPLV Guns
Like the HVLP equipment, LPLV
guns use conventional shop air and
do not require expensive turbine
units. The LPLV spray guns require
only 7 - 8 cfm of compressed air at
10 psi (as opposed to the 13 - 30 cfm
required for HVLP equipment).
Unlike HVLP equipment, the first
stage of atomization occurs within
the LPLV spray gun. Air and paint
are mixed inside an internal chamber
of the air cap to further assist in the
paint atomization. The LPLV
systems boast a transfer efficiency
ranging from 55 - 75 percent.
As with all the new spray
technologies, the LPLV systems have
obstacles that the painter must
overcome. Among these is a
pressurized cup, used in some LPLV
systems, which is only pressurized
when the gun trigger is pulled.
Some changes in spray technique
may be required to accommodate
this delay in material delivery.
LPLV spray equipment has gained
only minimal acceptance in the
automobile refinishing industry.
Prior to purchasing any paint
gun, consult your paint representative to determine which type of
gun will work best for the
application of the product you will
use. Your paint and/or spray gun
representative can also help you
determine the proper fluid tip/air
cap combination and proper gun
settings.
E. Recommended Practices for Spray Equipment
•Determine the price range you are willing to spend for spray equipment.
•Determine the types of coatings that will be sprayed through the
equipment and the atomization properties required for their proper
application.
•Choose spray equipment that will achieve the highest transfer efficiency
while providing the required atomization properties within your price
range.
•Prior to purchasing any paint gun, consult your paint representative to
determine what type of gun will work best for the application of the
product you will be using.
•Contact your paint representative and/or spray gun representative to
determine the fluid tip/air cap combination and gun settings that should
be used with the material being sprayed.
4. Spray Application
Techniques
B
oth the quality of the finish and
transfer efficiency greatly depend
on the technician’s skill and spraying
techniques. Cost and sophistication
of paint application equipment do not
ensure a quality finish. In order to
achieve a quality finish, the painter
must focus on the proper combination
of the following variables:
• Type of material to be sprayed
• Viscosity of material
• Thinner/reducer speed used
• Type of hardener or reactor used
• Addition of additives
• Booth air temperature
• Booth air flow
• Paint gun orifice size
• Paint gun air cap style
• Paint gun adjustments (air, fluid,
fan size)
• Distance of the spray gun from
surface
• Operator's spray gun speed
According to a study done by the
Pacific Northwest Pollution
Prevention Research Center,
"Transfer Efficiency and VOC
Emissions of Spray Gun Coating
Technologies in Wood Finishing", the
VOC emissions released during a
surface coating process are directly
related to the skill of the spray gun
operator. The study concluded that
"the difference in transfer efficiency
due to painter skill level with a
single gun type were often larger
than the differences between gun
types." In other words, proper
painting technique is often more
important than high transfer
efficient spray equipment when it
comes to reducing emissions. A
skilled technician will adjust
spraying style with each specific job
to compensate for the type of coating
being sprayed, the atmospheric
conditions, the size and shape of the
object being coated and the spray
equipment used. Due to all the
variables involved, it is impossible to
specify the one best spray technique
for all situations.
The quality of the
finish and transfer
efficiency depend on ht
skill and technique of
the technician
Painting technique is
often more important
than transfer efficient
spray equipment in
reducing emissions
In general, technicians should follow these basic rules.
A. Always have the correct gun setup for the coating to be sprayed and the size of
the area to be covered. These variables include the size of fluid tip and air cap
used. Fluid tip size is determined by the viscosity of the coating as well as the
flow rate setting of the gun. The viscosity is determined using a Zahn cup
measuring system (see figure 5, pg 14).
The flow rate can be determined through the following process:
For pressure fed spray equipment:
1. Turn off the atomizing air.
2. Aim spray gun tip towards a container (preferably a graduated container).
3. Pull the trigger of the gun, spraying the unatomized coating into the container
for 60 seconds.
4. Measure the amount of material expelled from the gun into the container to
determine the flow rate in ounces/minute.
12
13
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
4: Spray Application Techniques
For siphon fed spray equipment:
1. Measure the amount of material in the spray
cup
2. Pull the trigger of the gun, spraying the gun
at normal operating settings for 60 seconds.
3. Measure the amount of material left in the
spray cup to determine the volume of material
sprayed per minute.
Figure 5: Zahn Cup
B. Once the proper fluid tip size has been
determined, an air cap can be chosen. The
choice of an air cap depends on fluid tip size
and the desired air consumption of the gun.
Many paint gun manufacturers have fluid
tip/air cap combinations preset to help
determine the proper pairing. Because fluid
tips and air nozzles are precision machined to
very stringent tolerances, it is important that
their orifices remain free from obstructions to
assure proper atomization and spray pattern
uniformity.
4: Spray Application Techniques
F. The spray gun should be held at a distance of 6 - 8" from the substrate, and
this distance should be maintained with each stroke (Figure 7). In general, the
painter should use a 50 percent overlap for each pass, feathering the trigger at
the beginning and end of each stroke (Figure 8). This technique may need to be
altered slightly when applying high-metallic, high-solids basecoats and for some
three stage systems to avoid striping. The speed of each pass should be a
comfortable pace for the technician while maintaining a full wet coat, free of sags
or runs.
6
-
The spray gun
should be held 6-8”
from the substrate
8”
Figure 7: Proper Spray Distance and Technique
C. Set the air pressure at the lowest possible setting that will provide the
required degree of atomization. Too low of a setting may result in a heavy
centered spray pattern. Too high of a pressure setting will cause a dry spray
pattern, resulting in a dry rough finish. Never exceed the coating manufacturer’s
recommended air pressure settings.
Always hold the
gun perpendicular to
the substrate
The painter should
use a 50% overlap
for each pass
D. The size of the fan pattern will vary with the size and configuration of the
surface to be coated. For small spot repair operations, a small pattern is usually
preferable. For large panels, a full pattern is generally the most desirable setting.
E. When spraying, always hold the gun perpendicular to the surface being
sprayed, using parallel strokes. Never arc the spray gun (Figure 6), with two
notable exceptions:
◆ spraying
extremely large panels
that exceed the length
of the painters reach.
In these cases, the
painter will arc the gun
at the end of the pass to
help blend the overlap
areas, and
◆ performing panel
spotting or blending
operations.
14
Figure 6: Improper Spray Technique
Emission Reduction for Auto Body Shops
Figure 8: 50% Overlap Technique
15
Emission Reduction for Auto Body Shops
4: Spray Application Techniques
For siphon fed spray equipment:
1. Measure the amount of material in the spray
cup
2. Pull the trigger of the gun, spraying the gun
at normal operating settings for 60 seconds.
3. Measure the amount of material left in the
spray cup to determine the volume of material
sprayed per minute.
Figure 5: Zahn Cup
B. Once the proper fluid tip size has been
determined, an air cap can be chosen. The
choice of an air cap depends on fluid tip size
and the desired air consumption of the gun.
Many paint gun manufacturers have fluid
tip/air cap combinations preset to help
determine the proper pairing. Because fluid
tips and air nozzles are precision machined to
very stringent tolerances, it is important that
their orifices remain free from obstructions to
assure proper atomization and spray pattern
uniformity.
4: Spray Application Techniques
F. The spray gun should be held at a distance of 6 - 8" from the substrate, and
this distance should be maintained with each stroke (Figure 7). In general, the
painter should use a 50 percent overlap for each pass, feathering the trigger at
the beginning and end of each stroke (Figure 8). This technique may need to be
altered slightly when applying high-metallic, high-solids basecoats and for some
three stage systems to avoid striping. The speed of each pass should be a
comfortable pace for the technician while maintaining a full wet coat, free of sags
or runs.
6
-
The spray gun
should be held 6-8”
from the substrate
8”
Figure 7: Proper Spray Distance and Technique
C. Set the air pressure at the lowest possible setting that will provide the
required degree of atomization. Too low of a setting may result in a heavy
centered spray pattern. Too high of a pressure setting will cause a dry spray
pattern, resulting in a dry rough finish. Never exceed the coating manufacturer’s
recommended air pressure settings.
Always hold the
gun perpendicular to
the substrate
The painter should
use a 50% overlap
for each pass
D. The size of the fan pattern will vary with the size and configuration of the
surface to be coated. For small spot repair operations, a small pattern is usually
preferable. For large panels, a full pattern is generally the most desirable setting.
E. When spraying, always hold the gun perpendicular to the surface being
sprayed, using parallel strokes. Never arc the spray gun (Figure 6), with two
notable exceptions:
◆ spraying
extremely large panels
that exceed the length
of the painters reach.
In these cases, the
painter will arc the gun
at the end of the pass to
help blend the overlap
areas, and
◆ performing panel
spotting or blending
operations.
14
Figure 6: Improper Spray Technique
Emission Reduction for Auto Body Shops
Figure 8: 50% Overlap Technique
15
Emission Reduction for Auto Body Shops
4: Spray Application Techniques
G. Always paint small and medium size panels without breaking the stroke. With
larger panels, use a 4 - 5" overlap of the strokes, arcing the gun at the end of each
pass. When spotting or blending a panel, keep the blend as small as possible
without jeopardizing the appearance of the blend. To help insure proper coverage
of edges while reducing overspray, spray the outer boundaries of the panel first.
This technique, called banding, allows the painter to maintain adequate coverage
at the edges of the panel without extending the spray stroke well beyond the end
of the panel surface (Figure 9).
When applying a topcoat, use hiding power labels to determine when the
surface has been adequately covered. Through the use of these labels, the
technician can be assured of achieving proper coverage without the application of
excess material (Figure 10).
4: Spray Application Techniques
A. Recommended Practices for Spray Application Techniques
•Use the suggested air pressure and tip sizes for the specific product and
equipment being used.
•Always hold gun perpendicular to the surface being sprayed, using
parallel strokes. Never arc the gun.
•Feather the trigger at the beginning and end of each pass.
•Use a 50 percent overlap for each pass. This technique may need to
be altered slightly when applying high-metallic, high-solids basecoats and
some three stage systems.
•When painting small- and medium-sized panels, make each pass the full
length of the panel.
•With larger panels, use a comfortable stroke, with a 4 - 5 " overlap of the
strokes.
•If blending is necessary, keep the blend area as small as possible
without jeopardizing the appearance of the blend.
Always paint
small and medium
size panels without
breaking the stroke
•Spray the border edges of the substrate first (banding). This will assure
all edges are covered without extending the spray pattern well beyond the
borders of the object.
•Use color hiding power labels to determine the thickness of the applied
paint film. These markers will also indicate when adequate coverage
has been achieved.
Figure 9: Banding
16
Figure 10: Self-Adhering Power Label
Emission Reduction for Auto Body Shops
17
Emission Reduction for Auto Body Shops
4: Spray Application Techniques
G. Always paint small and medium size panels without breaking the stroke. With
larger panels, use a 4 - 5" overlap of the strokes, arcing the gun at the end of each
pass. When spotting or blending a panel, keep the blend as small as possible
without jeopardizing the appearance of the blend. To help insure proper coverage
of edges while reducing overspray, spray the outer boundaries of the panel first.
This technique, called banding, allows the painter to maintain adequate coverage
at the edges of the panel without extending the spray stroke well beyond the end
of the panel surface (Figure 9).
When applying a topcoat, use hiding power labels to determine when the
surface has been adequately covered. Through the use of these labels, the
technician can be assured of achieving proper coverage without the application of
excess material (Figure 10).
4: Spray Application Techniques
A. Recommended Practices for Spray Application Techniques
•Use the suggested air pressure and tip sizes for the specific product and
equipment being used.
•Always hold gun perpendicular to the surface being sprayed, using
parallel strokes. Never arc the gun.
•Feather the trigger at the beginning and end of each pass.
•Use a 50 percent overlap for each pass. This technique may need to
be altered slightly when applying high-metallic, high-solids basecoats and
some three stage systems.
•When painting small- and medium-sized panels, make each pass the full
length of the panel.
•With larger panels, use a comfortable stroke, with a 4 - 5 " overlap of the
strokes.
•If blending is necessary, keep the blend area as small as possible
without jeopardizing the appearance of the blend.
Always paint
small and medium
size panels without
breaking the stroke
•Spray the border edges of the substrate first (banding). This will assure
all edges are covered without extending the spray pattern well beyond the
borders of the object.
•Use color hiding power labels to determine the thickness of the applied
paint film. These markers will also indicate when adequate coverage
has been achieved.
Figure 9: Banding
16
Figure 10: Self-Adhering Power Label
Emission Reduction for Auto Body Shops
17
Emission Reduction for Auto Body Shops
5. Spray Equipment
Cleaning
T
he proper cleaning and
maintenance of spray equipment
has always been an essential part of
achieving a quality finish. This is
especially true with newer high
transfer efficiency spray
technologies. These new spray guns
are machined to very close tolerances
and are highly susceptible to dried
paint or other obstructions that can
affect the performance of the gun.
The EPA has estimated that 20
percent of all VOC emissions
released by automobile refinishers
occur during cleanup operations
(Figure 11).
Undercoats (17%)
• With the air hose and cup
removed, pull the gun trigger to
remove all remaining paint
from the siphon tube.
• Rinse the cup with a small amount
of thinner.
• Pour clean thinner into the cup
and reattach it to the gun.
• With the air supply reattached,
spray the thinner through the gun
to remove any paint remaining in
the interior orifices.
• Remove the cup and pour thinner
out of the cup.
• Wipe off the outside of the gun,
and inside and outside of the cup
using a rag or paper towel.
• Remove the air cap and clean with
a cleaning brush. A cleaning
brush is also used to clean other
external moving parts and behind
the trigger.
Surface Prep (8%)
Equipment
Cleaning (20%)
Figure 11: EPA Estimates of VOC
A. Manual Cleaning Processes
Prior to the introduction of paint
gun cleaning systems, all spray
equipment was cleaned by hand
using the following basic steps:
• Remove all remaining paint from
the cup.
Topcoats
• Reassemble the
gun and return it
to its storage area.
Many painters
remove the air cap
from the gun and
place it in the cup.
A small amount of
thinner is left in
the cup so the cap
can soak during
storage.
20% of VOC
emissions are released
during gun cleaning
operations
Using metal objects to clean the
small passageways can result in
severe damage which greatly reduces
the efficiency of the spray gun. If
needed, use a soft wooden toothpick to
remove obstructions from the orifices.
These manual cleaning techniques,
still commonly used in many small
shops, release an excessive amount
of VOCs to the atmosphere. They
Emission Reduction for Auto Body Shops
19
5. Spray Equipment
Cleaning
T
he proper cleaning and
maintenance of spray equipment
has always been an essential part of
achieving a quality finish. This is
especially true with newer high
transfer efficiency spray
technologies. These new spray guns
are machined to very close tolerances
and are highly susceptible to dried
paint or other obstructions that can
affect the performance of the gun.
The EPA has estimated that 20
percent of all VOC emissions
released by automobile refinishers
occur during cleanup operations
(Figure 11).
Undercoats (17%)
• With the air hose and cup
removed, pull the gun trigger to
remove all remaining paint
from the siphon tube.
• Rinse the cup with a small amount
of thinner.
• Pour clean thinner into the cup
and reattach it to the gun.
• With the air supply reattached,
spray the thinner through the gun
to remove any paint remaining in
the interior orifices.
• Remove the cup and pour thinner
out of the cup.
• Wipe off the outside of the gun,
and inside and outside of the cup
using a rag or paper towel.
• Remove the air cap and clean with
a cleaning brush. A cleaning
brush is also used to clean other
external moving parts and behind
the trigger.
Surface Prep (8%)
Equipment
Cleaning (20%)
Figure 11: EPA Estimates of VOC
A. Manual Cleaning Processes
Prior to the introduction of paint
gun cleaning systems, all spray
equipment was cleaned by hand
using the following basic steps:
• Remove all remaining paint from
the cup.
Topcoats
• Reassemble the
gun and return it
to its storage area.
Many painters
remove the air cap
from the gun and
place it in the cup.
A small amount of
thinner is left in
the cup so the cap
can soak during
storage.
20% of VOC
emissions are released
during gun cleaning
operations
Using metal objects to clean the
small passageways can result in
severe damage which greatly reduces
the efficiency of the spray gun. If
needed, use a soft wooden toothpick to
remove obstructions from the orifices.
These manual cleaning techniques,
still commonly used in many small
shops, release an excessive amount
of VOCs to the atmosphere. They
Emission Reduction for Auto Body Shops
19
5: Spray Equipment Cleaning
also expose the operator to solvents
for an extended amount of time.
B. Pneumatically Powered
Mechanical Cleaning Systems
Mechanical cleaning
systems reduce the
amount of thinner
used during the
cleaning process by
more than one half
Within the last few years the
mechanical gun wash system has
gained popularity in the refinishing
industry. Mechanical gun washers
(Figure 12) provide a safe, quick way
to effectively clean paint equipment,
including HVLP and LPLV spray
guns. The initial cleaning steps used
with mechanical gun cleaners are
the same as cleaning a gun using
manual techniques.
• Remove all the remaining paint
from the cup.
• With the air hose removed, pull
the trigger of the gun to remove
all remaining paint from the
siphon tube.
• Rinse the cup with a small amount
of thinner.
Following these initial cleaning
steps, the disassembled gun is then
20
5: Spray Equipment Cleaning
placed in the gun washer. The gun's
siphon tube is placed in the siphon
tube holder, and the gun trigger is
locked open using a locking plate.
The cup is simply inverted and
placed over a cleaning jet. The lid of
the washer is then closed and the
washer turned on. The operator can
leave the cleaning station and
remain away from paint, thinner,
and isocyanate fumes. After 1 - 3
minutes, the painter can remove the
cleaned spray gun from the washer.
The washer lid must then be closed
to prevent the thinner from
evaporating and to keep the VOC
emissions to a minimum.
With proper use and maintenance,
these units reduce the amount of
thinner used during the cleaning
process by more than one-half (some
manufacturers boast a 75 - 90
percent reduction). Mechanical
systems also reduce the labor time
needed for equipment cleaning by
over 60 percent.
Although VOC emissions from gun
washing systems (Figure 13) have
yet to be accurately measured, the
reduction should be substantial. In
addition, some solvent manufacturers offer a low VOC gun wash
solvent to further reduce emissions
from cleaning operations.
Figure 13: A Two Gun Capacity Gun Wash System
C. Recommended Practices for Spray Equipment Cleaning
•Use an air powered mechanical gun cleaning system.
•Use low VOC cleaning solvents.
•If cleaning guns manually, spray into an enclosed backdrop to capture
atomized solvents.
•Never use metal objects to remove dried paint or other obstructions from
the small orifices of spray equipment. If necessary, use a soft wooden
toothpick.
Figure 12: Enclosed Air Powered Mechanical Cleaning System
Emission Reduction for Auto Body Shops
21
Emission Reduction for Auto Body Shops
5: Spray Equipment Cleaning
also expose the operator to solvents
for an extended amount of time.
B. Pneumatically Powered
Mechanical Cleaning Systems
Mechanical cleaning
systems reduce the
amount of thinner
used during the
cleaning process by
more than one half
Within the last few years the
mechanical gun wash system has
gained popularity in the refinishing
industry. Mechanical gun washers
(Figure 12) provide a safe, quick way
to effectively clean paint equipment,
including HVLP and LPLV spray
guns. The initial cleaning steps used
with mechanical gun cleaners are
the same as cleaning a gun using
manual techniques.
• Remove all the remaining paint
from the cup.
• With the air hose removed, pull
the trigger of the gun to remove
all remaining paint from the
siphon tube.
• Rinse the cup with a small amount
of thinner.
Following these initial cleaning
steps, the disassembled gun is then
20
5: Spray Equipment Cleaning
placed in the gun washer. The gun's
siphon tube is placed in the siphon
tube holder, and the gun trigger is
locked open using a locking plate.
The cup is simply inverted and
placed over a cleaning jet. The lid of
the washer is then closed and the
washer turned on. The operator can
leave the cleaning station and
remain away from paint, thinner,
and isocyanate fumes. After 1 - 3
minutes, the painter can remove the
cleaned spray gun from the washer.
The washer lid must then be closed
to prevent the thinner from
evaporating and to keep the VOC
emissions to a minimum.
With proper use and maintenance,
these units reduce the amount of
thinner used during the cleaning
process by more than one-half (some
manufacturers boast a 75 - 90
percent reduction). Mechanical
systems also reduce the labor time
needed for equipment cleaning by
over 60 percent.
Although VOC emissions from gun
washing systems (Figure 13) have
yet to be accurately measured, the
reduction should be substantial. In
addition, some solvent manufacturers offer a low VOC gun wash
solvent to further reduce emissions
from cleaning operations.
Figure 13: A Two Gun Capacity Gun Wash System
C. Recommended Practices for Spray Equipment Cleaning
•Use an air powered mechanical gun cleaning system.
•Use low VOC cleaning solvents.
•If cleaning guns manually, spray into an enclosed backdrop to capture
atomized solvents.
•Never use metal objects to remove dried paint or other obstructions from
the small orifices of spray equipment. If necessary, use a soft wooden
toothpick.
Figure 12: Enclosed Air Powered Mechanical Cleaning System
Emission Reduction for Auto Body Shops
21
Emission Reduction for Auto Body Shops
6. Determining Product
VOC Content
T
he VOC content of paints or
related products may be found on
the Material Safety Data Sheet
(MSDS) provided by the
manufacturer. The MSDS lists the
VOC content of the product as
shipped in pounds per gallon, minus
water and non-VOC solvents
(Figure 14).
The listed VOC content gives the
user a means of comparing different
products. Use caution when
comparing these values because the
listed VOC content is of the product
as packaged, not necessarily its
sprayable form. Most products
require the addition of reducers,
thinners,
hardeners or
reactors
prior to
application.
These
additives
contain up to
100 percent
VOCs by
volume and
will change
the VOC
content of
the coating.
For example,
if a topcoat is
to be mixed
with a
hardener and
reducer at a
Figure 14: Determining
ratio of 2:1:1
respectively, then the VOC content
should be calculated as follows.
Paint VOC content
Hardener VOC content
Reducer VOC content
- 4.50 lbs/gal x 50% = 2.25
- 6.44 lbs/gal x 25% = 1.61
- 7.55 lbs/gal x 25% = 1.89
100% = 5.75 lbs/gal
This sprayable product has a VOC
content of 5.75 lbs/gal, not 4.50
lbs/gal as listed on its MSDS.
When comparing product VOC
content, the amount of the product
needed should also be considered. If
a product has a low VOC content but
requires 3 - 4 applications, it may
actually release a greater volume of
VOCs during the operation than a
high VOC product that will perform
equally well using two light coats.
MSDS sheets list
the VOC content as
packaged
VOC Content from the Material Safety Data Sheet
23
Emission Reduction for Auto Body Shops
6. Determining Product
VOC Content
T
he VOC content of paints or
related products may be found on
the Material Safety Data Sheet
(MSDS) provided by the
manufacturer. The MSDS lists the
VOC content of the product as
shipped in pounds per gallon, minus
water and non-VOC solvents
(Figure 14).
The listed VOC content gives the
user a means of comparing different
products. Use caution when
comparing these values because the
listed VOC content is of the product
as packaged, not necessarily its
sprayable form. Most products
require the addition of reducers,
thinners,
hardeners or
reactors
prior to
application.
These
additives
contain up to
100 percent
VOCs by
volume and
will change
the VOC
content of
the coating.
For example,
if a topcoat is
to be mixed
with a
hardener and
reducer at a
Figure 14: Determining
ratio of 2:1:1
respectively, then the VOC content
should be calculated as follows.
Paint VOC content
Hardener VOC content
Reducer VOC content
- 4.50 lbs/gal x 50% = 2.25
- 6.44 lbs/gal x 25% = 1.61
- 7.55 lbs/gal x 25% = 1.89
100% = 5.75 lbs/gal
This sprayable product has a VOC
content of 5.75 lbs/gal, not 4.50
lbs/gal as listed on its MSDS.
When comparing product VOC
content, the amount of the product
needed should also be considered. If
a product has a low VOC content but
requires 3 - 4 applications, it may
actually release a greater volume of
VOCs during the operation than a
high VOC product that will perform
equally well using two light coats.
MSDS sheets list
the VOC content as
packaged
VOC Content from the Material Safety Data Sheet
23
Emission Reduction for Auto Body Shops
6. Determining Product
VOC Content
T
he VOC content of paints or
related products may be found on
the Material Safety Data Sheet
(MSDS) provided by the
manufacturer. The MSDS lists the
VOC content of the product as
shipped in pounds per gallon, minus
water and non-VOC solvents
(Figure 14).
The listed VOC content gives the
user a means of comparing different
products. Use caution when
comparing these values because the
listed VOC content is of the product
as packaged, not necessarily its
sprayable form. Most products
require the addition of reducers,
thinners,
hardeners or
reactors
prior to
application.
These
additives
contain up to
100 percent
VOCs by
volume and
will change
the VOC
content of
the coating.
For example,
if a topcoat is
to be mixed
with a
hardener and
reducer at a
Figure 14: Determining
ratio of 2:1:1
respectively, then the VOC content
should be calculated as follows.
Paint VOC content
Hardener VOC content
Reducer VOC content
- 4.50 lbs/gal x 50% = 2.25
- 6.44 lbs/gal x 25% = 1.61
- 7.55 lbs/gal x 25% = 1.89
100% = 5.75 lbs/gal
This sprayable product has a VOC
content of 5.75 lbs/gal, not 4.50
lbs/gal as listed on its MSDS.
When comparing product VOC
content, the amount of the product
needed should also be considered. If
a product has a low VOC content but
requires 3 - 4 applications, it may
actually release a greater volume of
VOCs during the operation than a
high VOC product that will perform
equally well using two light coats.
MSDS sheets list
the VOC content as
packaged
VOC Content from the Material Safety Data Sheet
23
Emission Reduction for Auto Body Shops
7. Surface Prep
T
o achieve maximum adhesion
between the surface to be
refinished (the substrate) and the
undercoat, the surface must first be
cleansed of all contamination.
Cleaners are used to remove dirt,
grease, wax, silicon, mold release
agents (used in plastic and rubber
production) and any other contaminants that could compromise the
undercoat's adhesion to the substrate.
Many of these cleaners contain
toluene, which is listed as both a
VOC and a HAP. The EPA has
estimated that 8 percent of all VOCs
released during the refinishing
process result from surface prep
operations (Figure 15).
A. Soap and Water
Prior to working on an automobile,
all dirt should be removed from the
surface. To limit the amount of
solvent used for surface prep, use a
mild detergent or car wash soap to
clean off road grime and dirt. Then
rinse the surface with water to
remove any remaining soap. This is
one of the simplest and least
expensive means of reducing both
VOC emissions and material costs.
This process also flushes the dirt and
dust from body seams, reducing the
risk of dirt blowback during
refinishing. Biodegradable
detergents do not generate any VOC
emissions.
B. Synthetic Reducers
In the past, some painters have
used reducers as a pre-paint cleaner.
Reducers were popular mainly
Surface Prep (8%)
Under Coats (17%)
Equipment
Cleaning (20%)
Topcoats (55%)
Figure 15: EPA Estimates of VOC Emissions
because they eliminated the need for
the purchase of a second, less
versatile product. But reducers have
proved to be unsatisfactory pre-paint
cleaners for several reasons. Reducers
do not remove silicone from surfaces
as efficiently as commercially
produced cleaners and they have a
tendency to soften existing paints
and primers, causing them to swell
and blister. In addition, synthetic
reducers are 100 percent VOCs.
To limit the amount
of solvents used, a
mild detergent should
be used to remove road
grime and dirt.
C. Solvent-Based Cleaners
After all the road dirt and grime
have been removed, a solvent-based
cleaner can be used to effectively
remove all grease, wax and silicone
from the surface. Solvent-based
cleaners typically have a VOC
content of 6.0 lbs/gal and may
contain up to 100 percent solvent.
Most prep cleaners come in two
formulas and strengths. One type is
used for the initial surface cleaning
prior to sanding. They are designed
to remove heavy silicone, wax and
grease contamination. Many of these
cleaners contain harsh solvents such
Emission Reduction for Auto Body Shops
25
7: Surface Prep
Waterborne cleaners
have been developed
to replace high VOC
cleaners
as xylene and mineral spirits. These
highly concentrated solvents, if used
as a final wash, can cause poor
adhesion and/or "solvent popping" of
the topcoat.
generally come in two concentrations. One for the general
cleaning of surfaces, and another for
the final preparation of surfaces
prior to painting.
The second formula is designed for
the removal of light contamination
and is used primarily for final
cleaning prior to painting. These
final cleaners will not soften the
painted or primed surface like some
of the harsher solvents, nor do they
leave harmful residues on the
substrate.
Waterborne cleaners remove wax,
grease and silicone like their solventbased counterparts, but with less
than one-sixth the VOC content.
However, waterborne cleaners do
have three distinct disadvantages.
First, they may not remove heavy
silicon and grease contamination as
well as traditional solvent-based
cleaners. Second, they do not
evaporate as quickly as solventbased cleaners, thus increasing the
time needed for surface prep.
Finally, many of these cleaners are
not recommended for specific
substrates, such as water-based or
acrylic lacquer finishes.
D. Waterborne Cleaners
Recently, waterborne cleaners
have been developed to replace the
high VOC solvent-based cleaners.
Like their solvent-based
counterparts, waterborne cleaners
8. Undercoats
U
ndercoats are defined as all
material applied over the
substrate prior to the application of
a topcoat. These primers fall into
four separate categories:
• Prep Coats
• Primer-surfacers
• Primer-sealers
• Sealers
Undercoats (17%)
•If, due to heavy contamination, waterborne cleaners prove unsatisfactory,
use solvent-based cleaners for the initial cleaning of the surface. For
secondary cleaning operations, use the waterborne products.
•If waterborne cleaners prove unsatisfactory due to substrate make-up,
use solvent-based cleaners sparingly.
•Keep solvent-laden dirty rags in a closed container.
•Keep solvent containers closed when not in use.
•If possible, avoid operations that would necessitate multiple prepaint
cleaning operations (e.g., post surface prep repair operations which could
contaminate the substrate with grease or oil).
26
Emission Reduction for Auto Body Shops
1. Provide a corrosion resistant
coating.
Surface Prep (8%)
2. Provide maximum adhesion
between the substrate
and the next coating
to be applied.
Metal Conditioners/
Conversion Coatings
To reduce the VOCs emitted during surface prep operations, the following
practices should be implemented:
•Use waterborne cleaners when possible.
Use one brand of
product, following
all factory
recommendations
The prep coat has two major
functions:
The EPA has estimated that
undercoating processes account for
17 percent of all VOCs released during
refinishing operations (Figure 16).
E. Recommended Practices for Surface Prep
•Always wash dirt and grime from the vehicle using water or a soap and
water mixture.
representative with any questions
prior to application. It is also
advisable to use one brand of product
throughout the surface coating
operation while following all factory
recommendations. This will help
take the guess-work out of
determining which products are
compatible. It will also cut down
product inventory and product waste
within the shop.
Equipment
Cleaning (20%)
Figure 16: EPA Estimates of VOC
A. Prep Coats
The prep coat is applied directly
over bare metal or metal alloy,
galvanized or plated metal, plastic or
rubber substrates. The type of prep
coat used will vary depending on the
substrate and the type of coating to
be applied over the prep coat. It is
important to read and follow all
directions for these products very
carefully and contact your factory
Metal conditioners
are acidic solutions
that clean the surface
of the substrate,
removing contamTopcoats (55%)
inants that would
otherwise compromise
the bond between the
substrate and the undercoat. The
metal conditioner is generally wiped
on with a rag, and after 2-4 minutes
neutralized with water. Metal
conditioners work well only if the
surface has been wiped completely
dry after the neutralization process
has been completed. If moisture
remains on the metal surface and is
allowed to air dry, the integrity of
the bond between the substrate and
the primer-surfacer will be
compromised. The remaining
moisture may also cause oxidation to
form on the bare metal surface.
Emission Reduction for Auto Body Shops
27
7: Surface Prep
Waterborne cleaners
have been developed
to replace high VOC
cleaners
as xylene and mineral spirits. These
highly concentrated solvents, if used
as a final wash, can cause poor
adhesion and/or "solvent popping" of
the topcoat.
generally come in two concentrations. One for the general
cleaning of surfaces, and another for
the final preparation of surfaces
prior to painting.
The second formula is designed for
the removal of light contamination
and is used primarily for final
cleaning prior to painting. These
final cleaners will not soften the
painted or primed surface like some
of the harsher solvents, nor do they
leave harmful residues on the
substrate.
Waterborne cleaners remove wax,
grease and silicone like their solventbased counterparts, but with less
than one-sixth the VOC content.
However, waterborne cleaners do
have three distinct disadvantages.
First, they may not remove heavy
silicon and grease contamination as
well as traditional solvent-based
cleaners. Second, they do not
evaporate as quickly as solventbased cleaners, thus increasing the
time needed for surface prep.
Finally, many of these cleaners are
not recommended for specific
substrates, such as water-based or
acrylic lacquer finishes.
D. Waterborne Cleaners
Recently, waterborne cleaners
have been developed to replace the
high VOC solvent-based cleaners.
Like their solvent-based
counterparts, waterborne cleaners
8. Undercoats
U
ndercoats are defined as all
material applied over the
substrate prior to the application of
a topcoat. These primers fall into
four separate categories:
• Prep Coats
• Primer-surfacers
• Primer-sealers
• Sealers
Undercoats (17%)
•If, due to heavy contamination, waterborne cleaners prove unsatisfactory,
use solvent-based cleaners for the initial cleaning of the surface. For
secondary cleaning operations, use the waterborne products.
•If waterborne cleaners prove unsatisfactory due to substrate make-up,
use solvent-based cleaners sparingly.
•Keep solvent-laden dirty rags in a closed container.
•Keep solvent containers closed when not in use.
•If possible, avoid operations that would necessitate multiple prepaint
cleaning operations (e.g., post surface prep repair operations which could
contaminate the substrate with grease or oil).
26
Emission Reduction for Auto Body Shops
1. Provide a corrosion resistant
coating.
Surface Prep (8%)
2. Provide maximum adhesion
between the substrate
and the next coating
to be applied.
Metal Conditioners/
Conversion Coatings
To reduce the VOCs emitted during surface prep operations, the following
practices should be implemented:
•Use waterborne cleaners when possible.
Use one brand of
product, following
all factory
recommendations
The prep coat has two major
functions:
The EPA has estimated that
undercoating processes account for
17 percent of all VOCs released during
refinishing operations (Figure 16).
E. Recommended Practices for Surface Prep
•Always wash dirt and grime from the vehicle using water or a soap and
water mixture.
representative with any questions
prior to application. It is also
advisable to use one brand of product
throughout the surface coating
operation while following all factory
recommendations. This will help
take the guess-work out of
determining which products are
compatible. It will also cut down
product inventory and product waste
within the shop.
Equipment
Cleaning (20%)
Figure 16: EPA Estimates of VOC
A. Prep Coats
The prep coat is applied directly
over bare metal or metal alloy,
galvanized or plated metal, plastic or
rubber substrates. The type of prep
coat used will vary depending on the
substrate and the type of coating to
be applied over the prep coat. It is
important to read and follow all
directions for these products very
carefully and contact your factory
Metal conditioners
are acidic solutions
that clean the surface
of the substrate,
removing contamTopcoats (55%)
inants that would
otherwise compromise
the bond between the
substrate and the undercoat. The
metal conditioner is generally wiped
on with a rag, and after 2-4 minutes
neutralized with water. Metal
conditioners work well only if the
surface has been wiped completely
dry after the neutralization process
has been completed. If moisture
remains on the metal surface and is
allowed to air dry, the integrity of
the bond between the substrate and
the primer-surfacer will be
compromised. The remaining
moisture may also cause oxidation to
form on the bare metal surface.
Emission Reduction for Auto Body Shops
27
8: Undercoats
Conversion coating
leaves a phosphate
coating on the
substrate
Some water based
wash-primers
contain no VOCs
Following the metal conditioner, a
conversion coating is applied to the
substrate. This conversion coating,
usually phosphoric acid, etches the
metal to improve bonding with the
primer-surfacer. The conversion
coating also leaves a phosphate
coating on the surface of the
substrate, forming a more corrosionresistant surface.
Although this system contains low
amounts of VOCs (approximately 1.0
lbs/gal) it has some distinct
disadvantages. First, the primersurfacer must be sprayed on shortly
after the metal conditioning process
has been completed to avoid
corrosion of the metal. Second, the
employee performing the metal
conditioning operation is exposed to
an acidic solution which may cause
skin irritation. Finally, the metal
conditioner-conversion coating
system is time consuming, especially
when large areas require treatment.
Wash-Primers/Vinyl WashPrimers
Wash-primers were developed to
eliminate one of the steps associated
with metal conditioner and
conversion coating systems. Washprimers contain either phosphoric
acid or nickel dihydrogen phosphate,
which forms an adherent phosphate
coating when applied to steel and
aluminum. The acid also removes
rust, welding scale, and oil from the
bare metal while etching the surface
to insure the good adhesion of the
primer-surfacer.
Wash-primers are usually sprayed
on the metal surface using a hand
held plastic sprayer. Many wash
primers must be neutralized with
water and dried prior to surface
coating. Most of these conditioners
are low in VOCs, with average
contents of approximately 1.0 lb/gal.
Some of the newer water based
wash-primers do not contain VOCs.
Application of these products
requires caution. Some are designed
for use on steel surfaces only, and
should not be used on aluminum
substrates. Application to any
surface other then a bare metal
surface must also be avoided, as
lifting of the surface coat may result.
Some wash-primers are designed
for use on most metal surfaces as
well as plastic and rubber
substrates. These wash-primers
form a good bond between the
topcoat and the hard-to-adhere-to,
plastic and rubber surfaces.
Since wash-primers react with
metal surfaces, the use of a paint
gun for application should be
avoided. Wash-primers can react
with the metal spray gun, resulting
in an adhesive coating formed inside
the cup and on the interior
components of the gun. For this
reason, the solution should be
applied by hand or with a nonmetallic spray bottle. Check with
your paint supplier for specific
recommendations.
Zinc Phosphate Primers
Many automobile manufacturers
use zinc phosphate coatings as a
primer during surface coating
operations. In the factory, the
application of the zinc phosphate
coating is a multi-step, time
consuming process. But zinc
phosphate systems used as a primer
in the refinishing industry are a
28
Emission Reduction for Auto Body Shops
8: Undercoats
simple, one step, process. A light
coat of zinc phosphate is sprayed on
the metal surface and allowed to dry
for 30 to 60 minutes. The zinc
phosphate etches the substrate and
deposits a phosphate coating on the
surface to provide protection from
moisture. The result is a nonreactive roughened surface that is
perfect for the application of a
primer coat and needs no sanding
prior to surface coating. These
primers can be used on both steel
and aluminum surfaces. Zinc
phosphate does not have a pot-life,
but must be stirred before each use
due to excessive settling.
Zinc phosphate has a VOC concentration of 4.5 - 5.0 lbs/gal as
packaged. The VOC content of the
sprayable solution, reduced 1:1 with
enamel reducer, is as high as 6.0
lbs/gal.
In addition to the high VOC level,
zinc phosphate has four other
distinct disadvantages.
1. It is not recommended for use as a
primer under many waterborne
primer-surfacers.
2. Zinc phosphate does not adhere as
well as the wash-primers or selfetching primers.
3. The primer has no filling
capabilities.
4. The 30 - 60 minute curing time of
the zinc phosphate may be
unsatisfactory for production
surface coating operations.
Self-Etching Primers
Self-etching primers are usually
two component primers that provide
good corrosion resistance and good
adhesion to bare metal substrates.
These primers also have some filling
properties to hide minor surface
imperfections. The primed surface
may be sanded and recoated usually
after 45 - 60 minutes.
The VOC content of self etching
primers ranges from 5.0 - 6.5 lbs/gal
as packaged. With the addition of
the activator and reducer, the total
VOC content of the sprayable
product may be as high as 6.0 - 7.0
lbs/gal. In addition to the high VOC
content, these coatings also have the
disadvantage of a pot-life ranging
from several hours to several days
depending on the product.
Epoxy Primers
Epoxy primers are one of the most
versatile automotive paint products
on the market today. These two
component primers can be used as a
primer, primer-surfacer, primersealer, and adhesion promoter.
Epoxy primers provide excellent
corrosion resistance and adhesion to
bare metal and coated surfaces. The
epoxy resins in the primer produce a
strong chip resistant surface over the
substrate.
Epoxy primers are
one of the most
versatile products on
the market
Solvent-based self-etching epoxy
primers have a VOC content of
approximately 3.5 - 4.0 lbs/gal. With
the addition of the activator and
reducer, the sprayable primers have
VOC contents of approximately 5.0
lbs/gal.
These products also have a pot-life,
some as little as 6-8 hours, which
may increase the amount of waste
material generated. The curing time
for these primers ranges from 1 to 2
hours for the solvent-based, to as
much as 10 hours for the waterborne
Emission Reduction for Auto Body Shops
29
8: Undercoats
Conversion coating
leaves a phosphate
coating on the
substrate
Some water based
wash-primers
contain no VOCs
Following the metal conditioner, a
conversion coating is applied to the
substrate. This conversion coating,
usually phosphoric acid, etches the
metal to improve bonding with the
primer-surfacer. The conversion
coating also leaves a phosphate
coating on the surface of the
substrate, forming a more corrosionresistant surface.
Although this system contains low
amounts of VOCs (approximately 1.0
lbs/gal) it has some distinct
disadvantages. First, the primersurfacer must be sprayed on shortly
after the metal conditioning process
has been completed to avoid
corrosion of the metal. Second, the
employee performing the metal
conditioning operation is exposed to
an acidic solution which may cause
skin irritation. Finally, the metal
conditioner-conversion coating
system is time consuming, especially
when large areas require treatment.
Wash-Primers/Vinyl WashPrimers
Wash-primers were developed to
eliminate one of the steps associated
with metal conditioner and
conversion coating systems. Washprimers contain either phosphoric
acid or nickel dihydrogen phosphate,
which forms an adherent phosphate
coating when applied to steel and
aluminum. The acid also removes
rust, welding scale, and oil from the
bare metal while etching the surface
to insure the good adhesion of the
primer-surfacer.
Wash-primers are usually sprayed
on the metal surface using a hand
held plastic sprayer. Many wash
primers must be neutralized with
water and dried prior to surface
coating. Most of these conditioners
are low in VOCs, with average
contents of approximately 1.0 lb/gal.
Some of the newer water based
wash-primers do not contain VOCs.
Application of these products
requires caution. Some are designed
for use on steel surfaces only, and
should not be used on aluminum
substrates. Application to any
surface other then a bare metal
surface must also be avoided, as
lifting of the surface coat may result.
Some wash-primers are designed
for use on most metal surfaces as
well as plastic and rubber
substrates. These wash-primers
form a good bond between the
topcoat and the hard-to-adhere-to,
plastic and rubber surfaces.
Since wash-primers react with
metal surfaces, the use of a paint
gun for application should be
avoided. Wash-primers can react
with the metal spray gun, resulting
in an adhesive coating formed inside
the cup and on the interior
components of the gun. For this
reason, the solution should be
applied by hand or with a nonmetallic spray bottle. Check with
your paint supplier for specific
recommendations.
Zinc Phosphate Primers
Many automobile manufacturers
use zinc phosphate coatings as a
primer during surface coating
operations. In the factory, the
application of the zinc phosphate
coating is a multi-step, time
consuming process. But zinc
phosphate systems used as a primer
in the refinishing industry are a
28
Emission Reduction for Auto Body Shops
8: Undercoats
simple, one step, process. A light
coat of zinc phosphate is sprayed on
the metal surface and allowed to dry
for 30 to 60 minutes. The zinc
phosphate etches the substrate and
deposits a phosphate coating on the
surface to provide protection from
moisture. The result is a nonreactive roughened surface that is
perfect for the application of a
primer coat and needs no sanding
prior to surface coating. These
primers can be used on both steel
and aluminum surfaces. Zinc
phosphate does not have a pot-life,
but must be stirred before each use
due to excessive settling.
Zinc phosphate has a VOC concentration of 4.5 - 5.0 lbs/gal as
packaged. The VOC content of the
sprayable solution, reduced 1:1 with
enamel reducer, is as high as 6.0
lbs/gal.
In addition to the high VOC level,
zinc phosphate has four other
distinct disadvantages.
1. It is not recommended for use as a
primer under many waterborne
primer-surfacers.
2. Zinc phosphate does not adhere as
well as the wash-primers or selfetching primers.
3. The primer has no filling
capabilities.
4. The 30 - 60 minute curing time of
the zinc phosphate may be
unsatisfactory for production
surface coating operations.
Self-Etching Primers
Self-etching primers are usually
two component primers that provide
good corrosion resistance and good
adhesion to bare metal substrates.
These primers also have some filling
properties to hide minor surface
imperfections. The primed surface
may be sanded and recoated usually
after 45 - 60 minutes.
The VOC content of self etching
primers ranges from 5.0 - 6.5 lbs/gal
as packaged. With the addition of
the activator and reducer, the total
VOC content of the sprayable
product may be as high as 6.0 - 7.0
lbs/gal. In addition to the high VOC
content, these coatings also have the
disadvantage of a pot-life ranging
from several hours to several days
depending on the product.
Epoxy Primers
Epoxy primers are one of the most
versatile automotive paint products
on the market today. These two
component primers can be used as a
primer, primer-surfacer, primersealer, and adhesion promoter.
Epoxy primers provide excellent
corrosion resistance and adhesion to
bare metal and coated surfaces. The
epoxy resins in the primer produce a
strong chip resistant surface over the
substrate.
Epoxy primers are
one of the most
versatile products on
the market
Solvent-based self-etching epoxy
primers have a VOC content of
approximately 3.5 - 4.0 lbs/gal. With
the addition of the activator and
reducer, the sprayable primers have
VOC contents of approximately 5.0
lbs/gal.
These products also have a pot-life,
some as little as 6-8 hours, which
may increase the amount of waste
material generated. The curing time
for these primers ranges from 1 to 2
hours for the solvent-based, to as
much as 10 hours for the waterborne
Emission Reduction for Auto Body Shops
29
8: Undercoats
epoxy primers. It should also be
noted that some of these primers
contain lead and chrome, and their
activators may contain isocyanates.
Minimizing the
number of coats
applied limits the
amount of VOCs
emitted during the
primer-surfacer
stage
Primer-surfacers
should be used to fill
small imperfections
only
Adhesion Promoters
Adhesion promoters do not provide
the corrosion protection supplied by
other prep coats and should not be
used over bare metal substrates.
However, these products do provide
improved adhesion to plastic and
rubber components, as well as
painted surfaces.
The application of adhesion
promoters has become an important
step in the refinishing process with
the growing popularity of the harder,
more durable high tech surface
coatings. When sprayed over OEM
urethane, water-based, or high solids
paints and clears, adhesion
promoters provide improved
adhesion between the substrate and
the topcoat. Adhesion promoters
come ready to spray with a VOC
content of 6.5 - 7.0 lbs/gal. They
generally require a curing time of
approximately 15 - 30 minutes prior
to topcoating.
Recommended Practices for Prep
Coats
• Use versatile products such as
epoxy primers or self-etching
primers. These products may
alleviate the need for additional
surface coating operations such
as primer-surfacing or primer
sealing.
• If a self-etching primer or epoxy
primer is not desirable, use a
wash-primer, or metal conditioner,
conversion coating system.
• Avoid high VOC content zinc
phosphate primers.
B. Primer-Surfacers
The best way to limit VOC
emissions during the primer-surfacer
stage of the refinishing process is to
minimize the number of coats
applied. By ensuring that all major
body imperfections are removed prior
to priming operations, the technician
not only reduces the amount of
expensive material used during the
repair process, but also reduces the
amount of VOCs released. Primersurfacers should only be used to
remove small imperfections such as
sanding scratches; they are not
meant to fill dents.
Primer-surfacers are sprayed over
primers and have the following
functions:
1. Provide adhesion between the
primer and the material to be
applied over the primer-surfacer.
This includes the primer-sealers,
sealers, and topcoats.
2. Provide corrosion protection to the
metallic substrate.
3. Act as a filling material to cover
minor surface flaws.
4. Provide a coating that can be `
easily sanded to a smooth surface.
If a primer-sealer or sealer will not
be used over the primer-surfacer, or
if the sealer to be used is
transparent, the color of the primersurfacer must be considered. To
reduce VOC emissions and the
amount of paint required, choose a
primer which is a color that can
easily be covered by the topcoat.
Some primers on the market today
are tintable, allowing for easy
coverage of the surface-primer by the
topcoat. Many primer-surfacers still
contain lead and chromium. Most
two component primer-surfacers
contain isocyanates.
8: Undercoats
When applying primer-surfacers,
as with all coatings, it is important
to use a gun specially designed for
use with that type of product. Using
a properly operating primer gun
with the correct fluid tip/air cap
combination will help reduce
overspray and reduce the waste of
time and material due to a dry or
uneven coating.
Acrylic Lacquer Primer-Surfacer
Acrylic lacquer primer-surfacers
have been very popular in auto body
shops over the years. These primersurfacers provide an easy sanding
surface that drys quickly (usually
within 30 minutes) and has good
filling capabilities. Acrylic lacquer
primer-surfacers also provide good
corrosion resistance and excellent
holdout characteristics. Lacquer
based primer-surfacers are good for
spot repair and small panel jobs.
However, using lacquer-based
primers over deteriorating or
sensitive surfaces may result in
lifting or accelerated deterioration of
the old painted substrate. These
primers are not generally
recommended for large jobs due to
their poor durability and lack of
compatibility with the majority of
today's topcoat systems.
Acrylic lacquer primers usually
have a VOC content ranging from
4.5 - 5.0 lbs/gal. When thinned
(usually 100 - 125 percent) and
ready to spray, VOC content is
approximately 5.5 - 6.0 lbs/gal.
Alkyd Synthetic Enamel PrimerSurfacer
Alkyd enamel primer-surfacers
have good filling and holdout
properties as well as excellent
corrosion resistant qualities. They
produce a flexible, tough, chipresistant base that is excellent for
the application of a topcoat. Because
of their enamel base, these primersurfacers are less likely than their
lacquer-based counterparts to
adversely affect sensitive substrates.
Alkyd enamel primer-surfacers
contain 4.0 - 4.5 lbs/gal VOCs as
packaged. When thinned to a
sprayable concentration, the amount
of VOCs increases to 4.5 - 5.0 lbs
gal. The one distinct drawback of
alkyd enamel primer-surfacers is
their slow curing time. These
primer-surfacers must dry for at
least four hours before sanding
operations can be performed. For
this reason, alkyd enamel primersurfacers are not typically used for
spot repair operations, but rather
large panel surfaces and complete
paint jobs.
A properly operating
primer gun with
correct fluid tip/air
cap combination will
help reduce overspray
Self-Etching Primers (as a
Primer-Surfacer)
Self-etching primers are usually
two-component primers that provide
good corrosion resistance with fair
filling qualities. The primed surface
may be sanded and recoated after 45
- 60 minutes of drying time.
The VOC content of self etching
primers ranges from 5.0 - 6.5 lbs/gal
as packaged. With the addition of
the activator and reducer, the total
VOC content of the sprayable
product may be as high as 6.0 - 7.0
lbs/gal. In addition to high VOC
content, this product also has the
disadvantage of a pot-life ranging
from several hours to several days
depending on the product.
30
31
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
8: Undercoats
epoxy primers. It should also be
noted that some of these primers
contain lead and chrome, and their
activators may contain isocyanates.
Minimizing the
number of coats
applied limits the
amount of VOCs
emitted during the
primer-surfacer
stage
Primer-surfacers
should be used to fill
small imperfections
only
Adhesion Promoters
Adhesion promoters do not provide
the corrosion protection supplied by
other prep coats and should not be
used over bare metal substrates.
However, these products do provide
improved adhesion to plastic and
rubber components, as well as
painted surfaces.
The application of adhesion
promoters has become an important
step in the refinishing process with
the growing popularity of the harder,
more durable high tech surface
coatings. When sprayed over OEM
urethane, water-based, or high solids
paints and clears, adhesion
promoters provide improved
adhesion between the substrate and
the topcoat. Adhesion promoters
come ready to spray with a VOC
content of 6.5 - 7.0 lbs/gal. They
generally require a curing time of
approximately 15 - 30 minutes prior
to topcoating.
Recommended Practices for Prep
Coats
• Use versatile products such as
epoxy primers or self-etching
primers. These products may
alleviate the need for additional
surface coating operations such
as primer-surfacing or primer
sealing.
• If a self-etching primer or epoxy
primer is not desirable, use a
wash-primer, or metal conditioner,
conversion coating system.
• Avoid high VOC content zinc
phosphate primers.
B. Primer-Surfacers
The best way to limit VOC
emissions during the primer-surfacer
stage of the refinishing process is to
minimize the number of coats
applied. By ensuring that all major
body imperfections are removed prior
to priming operations, the technician
not only reduces the amount of
expensive material used during the
repair process, but also reduces the
amount of VOCs released. Primersurfacers should only be used to
remove small imperfections such as
sanding scratches; they are not
meant to fill dents.
Primer-surfacers are sprayed over
primers and have the following
functions:
1. Provide adhesion between the
primer and the material to be
applied over the primer-surfacer.
This includes the primer-sealers,
sealers, and topcoats.
2. Provide corrosion protection to the
metallic substrate.
3. Act as a filling material to cover
minor surface flaws.
4. Provide a coating that can be `
easily sanded to a smooth surface.
If a primer-sealer or sealer will not
be used over the primer-surfacer, or
if the sealer to be used is
transparent, the color of the primersurfacer must be considered. To
reduce VOC emissions and the
amount of paint required, choose a
primer which is a color that can
easily be covered by the topcoat.
Some primers on the market today
are tintable, allowing for easy
coverage of the surface-primer by the
topcoat. Many primer-surfacers still
contain lead and chromium. Most
two component primer-surfacers
contain isocyanates.
8: Undercoats
When applying primer-surfacers,
as with all coatings, it is important
to use a gun specially designed for
use with that type of product. Using
a properly operating primer gun
with the correct fluid tip/air cap
combination will help reduce
overspray and reduce the waste of
time and material due to a dry or
uneven coating.
Acrylic Lacquer Primer-Surfacer
Acrylic lacquer primer-surfacers
have been very popular in auto body
shops over the years. These primersurfacers provide an easy sanding
surface that drys quickly (usually
within 30 minutes) and has good
filling capabilities. Acrylic lacquer
primer-surfacers also provide good
corrosion resistance and excellent
holdout characteristics. Lacquer
based primer-surfacers are good for
spot repair and small panel jobs.
However, using lacquer-based
primers over deteriorating or
sensitive surfaces may result in
lifting or accelerated deterioration of
the old painted substrate. These
primers are not generally
recommended for large jobs due to
their poor durability and lack of
compatibility with the majority of
today's topcoat systems.
Acrylic lacquer primers usually
have a VOC content ranging from
4.5 - 5.0 lbs/gal. When thinned
(usually 100 - 125 percent) and
ready to spray, VOC content is
approximately 5.5 - 6.0 lbs/gal.
Alkyd Synthetic Enamel PrimerSurfacer
Alkyd enamel primer-surfacers
have good filling and holdout
properties as well as excellent
corrosion resistant qualities. They
produce a flexible, tough, chipresistant base that is excellent for
the application of a topcoat. Because
of their enamel base, these primersurfacers are less likely than their
lacquer-based counterparts to
adversely affect sensitive substrates.
Alkyd enamel primer-surfacers
contain 4.0 - 4.5 lbs/gal VOCs as
packaged. When thinned to a
sprayable concentration, the amount
of VOCs increases to 4.5 - 5.0 lbs
gal. The one distinct drawback of
alkyd enamel primer-surfacers is
their slow curing time. These
primer-surfacers must dry for at
least four hours before sanding
operations can be performed. For
this reason, alkyd enamel primersurfacers are not typically used for
spot repair operations, but rather
large panel surfaces and complete
paint jobs.
A properly operating
primer gun with
correct fluid tip/air
cap combination will
help reduce overspray
Self-Etching Primers (as a
Primer-Surfacer)
Self-etching primers are usually
two-component primers that provide
good corrosion resistance with fair
filling qualities. The primed surface
may be sanded and recoated after 45
- 60 minutes of drying time.
The VOC content of self etching
primers ranges from 5.0 - 6.5 lbs/gal
as packaged. With the addition of
the activator and reducer, the total
VOC content of the sprayable
product may be as high as 6.0 - 7.0
lbs/gal. In addition to high VOC
content, this product also has the
disadvantage of a pot-life ranging
from several hours to several days
depending on the product.
30
31
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
8: Undercoats
One-Component Waterborne
Primer-Surfacer
When waterborne primers were
introduced to the collision repair
market in the mid-to-late 1980's,
they were met with controversy and
resistance. Waterborne primers have
been reported to cause rusting of
untreated metallic substrates and
non-coated ferrous spray equipment
components. Some painters feel
these products have a curing time
too slow for production work,
especially in regions with high
humidity. While many of these
reported problems are due to
improper use of the product, long
curing times remain the primers’
greatest adversary.
Single component
waterborne primers
come ready to spray
with a 4.5 - 5.0
lbs/gal VOC content
These primers do have some very
beneficial qualities. They possess
excellent high building properties
with tremendous hold-out
capabilities. Many can be used on
flexible parts as a primer without
the need for the addition of a flex
agent. Single component waterborne
primers come ready to spray with a
4.5 - 5.0 lbs/gal VOC content,
resulting in a 20 percent reduction in
VOC emissions as compared to
conventional solvent- based primers.
Epoxy Primer (as a PrimerSurfacer)
As a primer-surfacer, epoxy
primers provide excellent filling
qualities and possess excellent holdout capabilities. The tough surface
produced by the epoxies makes a
good durable base for the application
of any topcoat.
32
Solvent-based self-etching epoxy
primers have a VOC content of
approximately 3.5 - 4.0 lbs/gal. With
the addition of the activator and
reducer, the sprayable primersurfacer formula has a VOC content
of up to 4.5 lbs/gal. Waterborne
epoxy primers, which are also
available, have a VOC content of less
then 2.1 lbs/gal for the sprayable
product.
Polyester Primer-Surfacer
Polyester primer-surfacers contain
polyester resins which, when cured,
form a durable surface with excellent
high building qualities and minimal
shrinkage. Because of their high
viscosity, polyester primer-surfacers
are best sprayed using gravity feed
spray equipment.
Polyester primer-surfacers have a
relatively long curing time, ranging
from 2 - 3 hours. These primersurfacers generally do not sand as
easily as other primer-surfacers, and
some loss in productivity may result.
The topcoats that can be applied to
these primer-surfacers are usually
limited to the newer polyurethanes.
The VOC content of polyester
primer-surfacers ranges from 4.6 to
5.0 lbs/gal thinned and ready to
spray.
8: Undercoats
Recommended Practices for
Primer-Surfacers
• Use low VOC waterborne primersurfacer products.
• If the curing time of waterborne
products is unsatisfactory,
consider the use of versatile
urethane or epoxy primers.
• To reduce VOC emissions, limit
material costs, and achieve a
better quality product, make sure
body work is done in such a
manner as to require only a
minimal amount of primersurfacer.
Lacquer Primer-Sealers
Lacquer primer-sealers produce
fair filling qualities with good
adhesion properties. These primers
are designed to be topcoated with
lacquer topcoats. One coat is
The choice of sealer
color affects not only
the coverage of the
topcoats but may
also affect the final
color shade of the
finish
• If a colored sealer will not be used,
make sure the primer-surfacer
used is a color that can easily be
covered with the desired topcoat.
• Use a properly operating primer
gun with the correct fluid tip/air
cap combination for your particular
type of primer-surfacer.
C. Primer-Sealers
Primer-sealers differ from primersurfacers in two basic areas. First,
primer sealers fill only very minor
imperfections. Second, they should
not be sanded prior to the
application of a topcoat.
Acrylic Urethane Enamel PrimerSurfacer
Primer-sealers must meet the
following performance criteria:
Acrylic urethane was developed for
the newer high tech topcoats. These
primer-surfacers provide high build
characteristics with little or no
shrinkage. Urethane primersurfacers have a VOC content
ranging from 4.3 - 5.0 lbs/gal after
the addition of the activator and
reducer. Urethane primer-surfacers
have a relatively slow curing time,
some requiring up to two hours to
cure under ideal conditions.
1. Provide corrosion resistance.
2. Provide adhesion to bare metal
substrate.
3. Fill minor surface imperfections.
4. Seal sanded surfaces to prevent
solvent penetration and bleedthrough.
5. Provide a single, neutral-colored
base for easy topcoat coverage.
Emission Reduction for Auto Body Shops
shade of the finish, especially when
using topcoats containing
transparent pigments. The primersealer should be as close to the color
of the factory sealer as possible.
The choice of sealer color affects
not only the coverage of the topcoats,
but may also affect the final color
Figure 17: Application of the Primer-Sealer
generally recommended prior to
painting with a 30 minute drying
time.
Lacquer primer-sealers are
commonly used for spot repair and
small paint jobs, but not generally
for large surface coating operations.
VOC content is approximately 6.0
lbs/gal as packaged in sprayable form.
Enamel Type Primer-Sealers
Enamel type primer-sealers also
have fair filling qualities with good
adhesion and holdout properties.
Usually used for large panel or
Emission Reduction for Auto Body Shops
33
8: Undercoats
One-Component Waterborne
Primer-Surfacer
When waterborne primers were
introduced to the collision repair
market in the mid-to-late 1980's,
they were met with controversy and
resistance. Waterborne primers have
been reported to cause rusting of
untreated metallic substrates and
non-coated ferrous spray equipment
components. Some painters feel
these products have a curing time
too slow for production work,
especially in regions with high
humidity. While many of these
reported problems are due to
improper use of the product, long
curing times remain the primers’
greatest adversary.
Single component
waterborne primers
come ready to spray
with a 4.5 - 5.0
lbs/gal VOC content
These primers do have some very
beneficial qualities. They possess
excellent high building properties
with tremendous hold-out
capabilities. Many can be used on
flexible parts as a primer without
the need for the addition of a flex
agent. Single component waterborne
primers come ready to spray with a
4.5 - 5.0 lbs/gal VOC content,
resulting in a 20 percent reduction in
VOC emissions as compared to
conventional solvent- based primers.
Epoxy Primer (as a PrimerSurfacer)
As a primer-surfacer, epoxy
primers provide excellent filling
qualities and possess excellent holdout capabilities. The tough surface
produced by the epoxies makes a
good durable base for the application
of any topcoat.
32
Solvent-based self-etching epoxy
primers have a VOC content of
approximately 3.5 - 4.0 lbs/gal. With
the addition of the activator and
reducer, the sprayable primersurfacer formula has a VOC content
of up to 4.5 lbs/gal. Waterborne
epoxy primers, which are also
available, have a VOC content of less
then 2.1 lbs/gal for the sprayable
product.
Polyester Primer-Surfacer
Polyester primer-surfacers contain
polyester resins which, when cured,
form a durable surface with excellent
high building qualities and minimal
shrinkage. Because of their high
viscosity, polyester primer-surfacers
are best sprayed using gravity feed
spray equipment.
Polyester primer-surfacers have a
relatively long curing time, ranging
from 2 - 3 hours. These primersurfacers generally do not sand as
easily as other primer-surfacers, and
some loss in productivity may result.
The topcoats that can be applied to
these primer-surfacers are usually
limited to the newer polyurethanes.
The VOC content of polyester
primer-surfacers ranges from 4.6 to
5.0 lbs/gal thinned and ready to
spray.
8: Undercoats
Recommended Practices for
Primer-Surfacers
• Use low VOC waterborne primersurfacer products.
• If the curing time of waterborne
products is unsatisfactory,
consider the use of versatile
urethane or epoxy primers.
• To reduce VOC emissions, limit
material costs, and achieve a
better quality product, make sure
body work is done in such a
manner as to require only a
minimal amount of primersurfacer.
Lacquer Primer-Sealers
Lacquer primer-sealers produce
fair filling qualities with good
adhesion properties. These primers
are designed to be topcoated with
lacquer topcoats. One coat is
The choice of sealer
color affects not only
the coverage of the
topcoats but may
also affect the final
color shade of the
finish
• If a colored sealer will not be used,
make sure the primer-surfacer
used is a color that can easily be
covered with the desired topcoat.
• Use a properly operating primer
gun with the correct fluid tip/air
cap combination for your particular
type of primer-surfacer.
C. Primer-Sealers
Primer-sealers differ from primersurfacers in two basic areas. First,
primer sealers fill only very minor
imperfections. Second, they should
not be sanded prior to the
application of a topcoat.
Acrylic Urethane Enamel PrimerSurfacer
Primer-sealers must meet the
following performance criteria:
Acrylic urethane was developed for
the newer high tech topcoats. These
primer-surfacers provide high build
characteristics with little or no
shrinkage. Urethane primersurfacers have a VOC content
ranging from 4.3 - 5.0 lbs/gal after
the addition of the activator and
reducer. Urethane primer-surfacers
have a relatively slow curing time,
some requiring up to two hours to
cure under ideal conditions.
1. Provide corrosion resistance.
2. Provide adhesion to bare metal
substrate.
3. Fill minor surface imperfections.
4. Seal sanded surfaces to prevent
solvent penetration and bleedthrough.
5. Provide a single, neutral-colored
base for easy topcoat coverage.
Emission Reduction for Auto Body Shops
shade of the finish, especially when
using topcoats containing
transparent pigments. The primersealer should be as close to the color
of the factory sealer as possible.
The choice of sealer color affects
not only the coverage of the topcoats,
but may also affect the final color
Figure 17: Application of the Primer-Sealer
generally recommended prior to
painting with a 30 minute drying
time.
Lacquer primer-sealers are
commonly used for spot repair and
small paint jobs, but not generally
for large surface coating operations.
VOC content is approximately 6.0
lbs/gal as packaged in sprayable form.
Enamel Type Primer-Sealers
Enamel type primer-sealers also
have fair filling qualities with good
adhesion and holdout properties.
Usually used for large panel or
Emission Reduction for Auto Body Shops
33
8: Undercoats
complete paint jobs, only one coat of
primer-sealer is generally needed
prior to topcoating. VOC content
averages 4.5 - 5.0 lbs/gal.
Single Component Waterborne
Primer-Surfacer (as a Primer-Sealer)
Single component water-based
primers possess excellent high
building qualities and work well as
barrier coats with tremendous holdout properties. Many can be used on
flexible parts as a primer without the
addition of a flex agent.
These primers come ready-to-spray
with a 4.5 - 5.0 lbs/gal VOC content.
Because water is used as the primary
solvent, the flash and cure times of
these products are relatively long,
especially in regions of high
humidity. The water may also cause
the corrosion of non-coated ferrous
application equipment if not cleaned
properly.
Epoxy Primer (as a Primer-Sealer)
As a primer-sealer, epoxy primers
provide excellent hold out
capabilities. The tough surface
produced by the epoxies makes a
good durable base for the application
of all topcoats.
Solvent-based self-etching epoxy
primers have a VOC content of
approximately 3.5 - 4.0 lbs/gal. With
the addition of the activator and
reducer, the sprayable primer-surfacer
formula has a VOC content of 4.5
lbs/gal. Waterborne epoxy primers
have a VOC content of less then 2.1
lbs/gal for the sprayable product.
Urethane primer-sealers provide
high build characteristics with little
or no shrinkage. They also have
superior holdout properties which
make them an excellent primersealer.
Urethane primer-sealers have a
VOC content ranging from 4.3 - 5.0
lbs/gal after the addition of the
activator and reducers. Urethanes
must usually be topcoated within 24
hours to avoid the need for sanding
and recoating.
D. Sealers
Recommended Practices for
Primer-Sealers
8: Undercoats
In general, sealer types include
lacquer sealers, enamel sealers, and
urethane sealers. These sealers are
developed to be coated by lacquer,
enamel and urethane topcoats
respectively, and generally require
only one coat prior to painting.
These sealers come ready to spray
with VOC contents of approximately
6.5, 6.0, 6.0 lbs/gal respectively.
As with primer-sealers, the choice
of sealer color affects coverage and
the final shade of your topcoat,
especially topcoats containing
transparent pigments. Therefore,
when choosing a sealer, always take
into account the sealer color as well
as the topcoating.
• Use low VOC primer-sealers such
as single component waterborne,
or waterborne epoxy primers.
Along with these basic sealers,
there are also specialty sealers
available for use on specific problem
surfaces.
• The use of low VOC urethane
primer-sealers would also be an
acceptable choice.
Tie Coat Sealers
• Always choose primer-sealer color
that can be easily covered by the
topcoat to be sprayed, or choose a
tintable primer-sealer and tint it to
an easily covered shade.
Sealers are applied prior to the
topcoat if needed. They should have
the following qualities:
1. Provide adhesion between the
topcoat and the surface.
2. Provide a single, neutral-colored
base for easy coverage.
3. Seal sanded surfaces to prevent
solvent penetration.
4. Fill minor imperfections.
Tie coat sealers are used to
achieve extra adhesion between
lacquer topcoats and factory enamel
finishes.
Recommended Practices for
Sealers
• Chose the proper sealer for each
specific job.
• If filling capabilities are required,
use primer-sealer in place of a
sealer.
• Always choose a primer-sealer
color that can be easily covered
with the next coating, or choose a
tintable primer-sealer.
When choosing a
sealer, take into
account the color of
the sealer as well as
the topcoating to be
applied
Barrier Coat Sealers
Barrier coat sealers are applied
over very sensitive and or checked
surfaces. These sealers supply
superb holdout, preventing the
lifting or checking of the new
topcoat.
Acrylic Urethane Primer-Sealers
34
35
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
8: Undercoats
complete paint jobs, only one coat of
primer-sealer is generally needed
prior to topcoating. VOC content
averages 4.5 - 5.0 lbs/gal.
Single Component Waterborne
Primer-Surfacer (as a Primer-Sealer)
Single component water-based
primers possess excellent high
building qualities and work well as
barrier coats with tremendous holdout properties. Many can be used on
flexible parts as a primer without the
addition of a flex agent.
These primers come ready-to-spray
with a 4.5 - 5.0 lbs/gal VOC content.
Because water is used as the primary
solvent, the flash and cure times of
these products are relatively long,
especially in regions of high
humidity. The water may also cause
the corrosion of non-coated ferrous
application equipment if not cleaned
properly.
Epoxy Primer (as a Primer-Sealer)
As a primer-sealer, epoxy primers
provide excellent hold out
capabilities. The tough surface
produced by the epoxies makes a
good durable base for the application
of all topcoats.
Solvent-based self-etching epoxy
primers have a VOC content of
approximately 3.5 - 4.0 lbs/gal. With
the addition of the activator and
reducer, the sprayable primer-surfacer
formula has a VOC content of 4.5
lbs/gal. Waterborne epoxy primers
have a VOC content of less then 2.1
lbs/gal for the sprayable product.
Urethane primer-sealers provide
high build characteristics with little
or no shrinkage. They also have
superior holdout properties which
make them an excellent primersealer.
Urethane primer-sealers have a
VOC content ranging from 4.3 - 5.0
lbs/gal after the addition of the
activator and reducers. Urethanes
must usually be topcoated within 24
hours to avoid the need for sanding
and recoating.
D. Sealers
Recommended Practices for
Primer-Sealers
8: Undercoats
In general, sealer types include
lacquer sealers, enamel sealers, and
urethane sealers. These sealers are
developed to be coated by lacquer,
enamel and urethane topcoats
respectively, and generally require
only one coat prior to painting.
These sealers come ready to spray
with VOC contents of approximately
6.5, 6.0, 6.0 lbs/gal respectively.
As with primer-sealers, the choice
of sealer color affects coverage and
the final shade of your topcoat,
especially topcoats containing
transparent pigments. Therefore,
when choosing a sealer, always take
into account the sealer color as well
as the topcoating.
• Use low VOC primer-sealers such
as single component waterborne,
or waterborne epoxy primers.
Along with these basic sealers,
there are also specialty sealers
available for use on specific problem
surfaces.
• The use of low VOC urethane
primer-sealers would also be an
acceptable choice.
Tie Coat Sealers
• Always choose primer-sealer color
that can be easily covered by the
topcoat to be sprayed, or choose a
tintable primer-sealer and tint it to
an easily covered shade.
Sealers are applied prior to the
topcoat if needed. They should have
the following qualities:
1. Provide adhesion between the
topcoat and the surface.
2. Provide a single, neutral-colored
base for easy coverage.
3. Seal sanded surfaces to prevent
solvent penetration.
4. Fill minor imperfections.
Tie coat sealers are used to
achieve extra adhesion between
lacquer topcoats and factory enamel
finishes.
Recommended Practices for
Sealers
• Chose the proper sealer for each
specific job.
• If filling capabilities are required,
use primer-sealer in place of a
sealer.
• Always choose a primer-sealer
color that can be easily covered
with the next coating, or choose a
tintable primer-sealer.
When choosing a
sealer, take into
account the color of
the sealer as well as
the topcoating to be
applied
Barrier Coat Sealers
Barrier coat sealers are applied
over very sensitive and or checked
surfaces. These sealers supply
superb holdout, preventing the
lifting or checking of the new
topcoat.
Acrylic Urethane Primer-Sealers
34
35
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
9. Topcoats
A
pplication of the topcoat is the
next phase of the surface coating
operation. Topcoats are applied
directly over the undercoats, which
may be a prep coat, primer-surfacer,
primer-sealer or sealer. Topcoats
include paints and clears that give the
surface the color, gloss and durability
demanded by today's consumers.
The EPA estimates indicate that
topcoats are responsible for 55 percent
of all VOCs released during surface
coating operations (Figure 18).
flakes, as well as their location
within the finish layer, affect the
perceived color and richness of the
painted surface. The positioning of
these flakes within the finish is
dictated by the type of paint, the
speed of the thinner and hardener,
the type and settings of the spray
equipment, along with the spraying
techniques used.
Topcoats are categorized as either
single stage or two stage systems.
Three stage systems are used by
some automobile manufacturers, but
will not be addressed in this manual.
Topcoats are
responsible for 55%
of the VOCs released
during surface
coating operations
Many paint
companies offer
the option of
Surface Prep (8%)
Undercoats (17%)
high-solids paints
or clears which
contain 60
percent or more
solids by volume.
Solvents such as
glycol esters,
Equipment
esters and
Cleaning (20%)
ketones, which
Topcoats (55%)
keep more of the
solids in
suspension
with
Figure 18: EPA Estimates of VOC Emissions
less solvent, are
generally used in
Paints are considered to be either
high-solid paints, primers and clears.
solid or metallic-type topcoat. The
These systems reduce the amount of
solid color paints are made up of
VOCs released by up to 75 percent,
solvents, binders and opaque
while reducing the amount of paint
pigments that produce the color of
material needed by almost one-half
the finish. Metallic colors are made
as compared to conventional systems.
up of solvents, binders and opaque
Generally, only one to three coats are
pigments like the solid colors, but
needed to achieve adequate coverage
also include small light-refracting
using high solids paints.
flakes. These small metallic,
polychrome or mica flakes refract
High solids paints have a high
some of the light that enters the
viscosity in their sprayable form.
finish, resulting in a surface that
High viscosity materials are more
appears richer and deeper in color.
difficult to atomize into the fine
The orientation of the refracting
droplets needed to achieve a quality
37
Emission Reduction for Auto Body Shops
9. Topcoats
A
pplication of the topcoat is the
next phase of the surface coating
operation. Topcoats are applied
directly over the undercoats, which
may be a prep coat, primer-surfacer,
primer-sealer or sealer. Topcoats
include paints and clears that give the
surface the color, gloss and durability
demanded by today's consumers.
The EPA estimates indicate that
topcoats are responsible for 55 percent
of all VOCs released during surface
coating operations (Figure 18).
flakes, as well as their location
within the finish layer, affect the
perceived color and richness of the
painted surface. The positioning of
these flakes within the finish is
dictated by the type of paint, the
speed of the thinner and hardener,
the type and settings of the spray
equipment, along with the spraying
techniques used.
Topcoats are categorized as either
single stage or two stage systems.
Three stage systems are used by
some automobile manufacturers, but
will not be addressed in this manual.
Topcoats are
responsible for 55%
of the VOCs released
during surface
coating operations
Many paint
companies offer
the option of
Surface Prep (8%)
Undercoats (17%)
high-solids paints
or clears which
contain 60
percent or more
solids by volume.
Solvents such as
glycol esters,
Equipment
esters and
Cleaning (20%)
ketones, which
Topcoats (55%)
keep more of the
solids in
suspension
with
Figure 18: EPA Estimates of VOC Emissions
less solvent, are
generally used in
Paints are considered to be either
high-solid paints, primers and clears.
solid or metallic-type topcoat. The
These systems reduce the amount of
solid color paints are made up of
VOCs released by up to 75 percent,
solvents, binders and opaque
while reducing the amount of paint
pigments that produce the color of
material needed by almost one-half
the finish. Metallic colors are made
as compared to conventional systems.
up of solvents, binders and opaque
Generally, only one to three coats are
pigments like the solid colors, but
needed to achieve adequate coverage
also include small light-refracting
using high solids paints.
flakes. These small metallic,
polychrome or mica flakes refract
High solids paints have a high
some of the light that enters the
viscosity in their sprayable form.
finish, resulting in a surface that
High viscosity materials are more
appears richer and deeper in color.
difficult to atomize into the fine
The orientation of the refracting
droplets needed to achieve a quality
37
Emission Reduction for Auto Body Shops
9: Topcoats
To help reduce the
mount of paint waste
and VOCs released,
color coats should be
mixed in-house
automotive finish. The high solids
coatings, due to their high viscosity,
also have poor metallic flake
orientation capabilities compared to
low solids coatings.
Whichever paint system is used, it
is important to mix material as
specified by the manufacturer.
Today's high-tech finishes, especially
when used in the newer HVLP spray
equipment, must be mixed accurately
to produce a high quality finish.
Consequently, painters must have
the means to accurately measure the
volumes of paint, reducers, and
additives during mixing. To achieve
the proper viscosity of a paint mixture
for specific conditions, a viscosity cup
(Figure 5, pg 14) should be used when
mixing all paints and clears. This
will help to ensure viscosity of the
material is adequate to achieve a
good quality finish while keeping
overspray and VOCs to a minimum.
To help reduce the amount of
paint waste and VOCs released, color
coats should be mixed in-house.
Mixing paints in-house allows the
facility to make any tint changes
needed to achieve a color match. It
also gives the technician the freedom
to mix only the amount of paint
required for that specific job. Paint
jobbers will generally only mix paint
in quantities of one pint or greater.
This amount is often more than
needed, resulting in waste paint.
Spray-out cards with appropriate
information on the product used and
color match should be made and
catalogued. This will decrease the
time and money wasted matching a
color, especially considering the
number of colors and variations of
paint formulas for each type of
vehicle on the road today.
A. Single Stage Topcoats
Acrylic Lacquer
Lacquer finishes are most
commonly used for small spot repair
operations due to their fast cure time
and minimal overspray concerns.
Lacquer coatings cure solely due to
solvent evaporation, producing a
hard, brittle finish.
Because quick evaporating
solvents are used to thin lacquer
coatings, the finish does not have a
chance to flow adequately prior to
drying, resulting in a dull, relatively
rough finish. The fully cured lacquer
finish must be polished to achieve a
smooth, high-gloss finish. Usually
four to five coats of lacquer are
applied to insure proper paint
thickness is maintained after
polishing.
The hard, brittle coating of the
lacquer products is not designed to
withstand the flexing of nonrigid
surfaces. For this reason, a flex
additive is used when coating rubber
and flexible plastic components with
lacquer paints.
To achieve the correct viscosity for
conventional spray gun application,
lacquer paints are thinned 125 - 150
percent. This high solvent concentration results in a VOC content of
6.0 - 6.5 lbs/gal, 70 - 90 percent by
volume. The EPA estimates that the
use of lacquer paints increases the
amount of VOC emissions by 45
percent compared to enamel topcoats.
Alkyd Enamel
Alkyd enamels are the least
durable of all the automotive paints.
Alkyd enamels dry in a two stage
curing process. First, the finish
38
Emission Reduction for Auto Body Shops
9: Topcoats
dries by solvent evaporation similar
to lacquer type coatings. This stage
takes from seven to nine hours,
depending on drying conditions. In
the following six hours to 30 days,
the enamel cures due to the oxidation
of the binder as it reacts with air.
The drying time, the gloss and the
durability of the finish can all be
improved with the addition of a
chemical hardener. However, these
hardeners not only reduce the potlife of the paint, they also release
isocyanates during spraying and
curing operations.
Alkyd enamels are thinned 15 - 33
percent depending on the brand.
Only two to three coats usually are
required to provide adequate
coverage. Alkyd enamels contain
approximately 5.0 - 5.5 lbs/gal VOCs
in sprayable form, approximately 55
- 75 percent VOCs by volume.
Acrylic Enamel
Acrylic enamels are used for both
spot repairs as well as overall
painting operations. These enamels
offer more durable finishes and
faster drying times than the alkyd
enamels. Acrylic enamels dry in five
to seven hours, with the second
curing period taking an additional
six to 72 hours at 72°F.
Drying time, gloss and durability
of acrylic enamels can all be improved
with the addition of a chemical
hardener. These hardeners increased
the durability of the surface by
almost 50 percent compared to
acrylic enamels without hardeners.
Acrylic enamels, on average,
contain 5.0 - 5.5 lbs/gal VOCs in
their sprayable form. With acrylic
enamels requiring only two to three
coats to provide adequate coverage,
the VOCs are reduced by 45 percent
over lacquer type paints.
Enamel products usually do not
need the addition of a flex agent on
fairly rigid parts. If used on very
flexible parts, the addition of a flex
agent may be required, increasing
the VOC content.
Polyurethane Enamel Single
Stage Topcoats
Polyurethane topcoats are a twopart painting system requiring the
addition of a hardener or reactor (the
second component) to assure proper
curing of the finish. Polyurethane
top coats have great spraying charac teristics along with good metallic
flow properties. They produce a high
gloss, chemically resistant finish that
will withstand the effects of
ultraviolet radiation for many years.
Polyurethane enamels have a VOC
concentration of 5.0 - 5.5 lbs/gal in
their sprayable form. The high VOC
content of these coatings is offset by
their excellent coverage. Normally,
only two to three coats are needed to
provide a good quality finish. Polyurethane finishes have good flexibility
and can be used over flexible parts
without the addition of flex additives.
Acrylic Urethane Enamel
Acrylic urethanes produce one of
the most durable automotive finishes
available today. They have twice the
durability of polyurethanes, with less
curing time needed to achieve a tack
free finish.
Acrylic urethanes have a relatively
high VOC content (ranging from 5.0 5.5 lbs/gal) in their sprayable form.
Generally, only two coats of these
topcoats are required to produce a
quality finish, reducing the amount
of material needed for the top
coating process.
With acrylic enamels
requiring only twothree coats to provide
adequate coverage,
the VOCs are reduced
by 45% over lacquers
Emission Reduction for Auto Body Shops
39
9: Topcoats
To help reduce the
mount of paint waste
and VOCs released,
color coats should be
mixed in-house
automotive finish. The high solids
coatings, due to their high viscosity,
also have poor metallic flake
orientation capabilities compared to
low solids coatings.
Whichever paint system is used, it
is important to mix material as
specified by the manufacturer.
Today's high-tech finishes, especially
when used in the newer HVLP spray
equipment, must be mixed accurately
to produce a high quality finish.
Consequently, painters must have
the means to accurately measure the
volumes of paint, reducers, and
additives during mixing. To achieve
the proper viscosity of a paint mixture
for specific conditions, a viscosity cup
(Figure 5, pg 14) should be used when
mixing all paints and clears. This
will help to ensure viscosity of the
material is adequate to achieve a
good quality finish while keeping
overspray and VOCs to a minimum.
To help reduce the amount of
paint waste and VOCs released, color
coats should be mixed in-house.
Mixing paints in-house allows the
facility to make any tint changes
needed to achieve a color match. It
also gives the technician the freedom
to mix only the amount of paint
required for that specific job. Paint
jobbers will generally only mix paint
in quantities of one pint or greater.
This amount is often more than
needed, resulting in waste paint.
Spray-out cards with appropriate
information on the product used and
color match should be made and
catalogued. This will decrease the
time and money wasted matching a
color, especially considering the
number of colors and variations of
paint formulas for each type of
vehicle on the road today.
A. Single Stage Topcoats
Acrylic Lacquer
Lacquer finishes are most
commonly used for small spot repair
operations due to their fast cure time
and minimal overspray concerns.
Lacquer coatings cure solely due to
solvent evaporation, producing a
hard, brittle finish.
Because quick evaporating
solvents are used to thin lacquer
coatings, the finish does not have a
chance to flow adequately prior to
drying, resulting in a dull, relatively
rough finish. The fully cured lacquer
finish must be polished to achieve a
smooth, high-gloss finish. Usually
four to five coats of lacquer are
applied to insure proper paint
thickness is maintained after
polishing.
The hard, brittle coating of the
lacquer products is not designed to
withstand the flexing of nonrigid
surfaces. For this reason, a flex
additive is used when coating rubber
and flexible plastic components with
lacquer paints.
To achieve the correct viscosity for
conventional spray gun application,
lacquer paints are thinned 125 - 150
percent. This high solvent concentration results in a VOC content of
6.0 - 6.5 lbs/gal, 70 - 90 percent by
volume. The EPA estimates that the
use of lacquer paints increases the
amount of VOC emissions by 45
percent compared to enamel topcoats.
Alkyd Enamel
Alkyd enamels are the least
durable of all the automotive paints.
Alkyd enamels dry in a two stage
curing process. First, the finish
38
Emission Reduction for Auto Body Shops
9: Topcoats
dries by solvent evaporation similar
to lacquer type coatings. This stage
takes from seven to nine hours,
depending on drying conditions. In
the following six hours to 30 days,
the enamel cures due to the oxidation
of the binder as it reacts with air.
The drying time, the gloss and the
durability of the finish can all be
improved with the addition of a
chemical hardener. However, these
hardeners not only reduce the potlife of the paint, they also release
isocyanates during spraying and
curing operations.
Alkyd enamels are thinned 15 - 33
percent depending on the brand.
Only two to three coats usually are
required to provide adequate
coverage. Alkyd enamels contain
approximately 5.0 - 5.5 lbs/gal VOCs
in sprayable form, approximately 55
- 75 percent VOCs by volume.
Acrylic Enamel
Acrylic enamels are used for both
spot repairs as well as overall
painting operations. These enamels
offer more durable finishes and
faster drying times than the alkyd
enamels. Acrylic enamels dry in five
to seven hours, with the second
curing period taking an additional
six to 72 hours at 72°F.
Drying time, gloss and durability
of acrylic enamels can all be improved
with the addition of a chemical
hardener. These hardeners increased
the durability of the surface by
almost 50 percent compared to
acrylic enamels without hardeners.
Acrylic enamels, on average,
contain 5.0 - 5.5 lbs/gal VOCs in
their sprayable form. With acrylic
enamels requiring only two to three
coats to provide adequate coverage,
the VOCs are reduced by 45 percent
over lacquer type paints.
Enamel products usually do not
need the addition of a flex agent on
fairly rigid parts. If used on very
flexible parts, the addition of a flex
agent may be required, increasing
the VOC content.
Polyurethane Enamel Single
Stage Topcoats
Polyurethane topcoats are a twopart painting system requiring the
addition of a hardener or reactor (the
second component) to assure proper
curing of the finish. Polyurethane
top coats have great spraying charac teristics along with good metallic
flow properties. They produce a high
gloss, chemically resistant finish that
will withstand the effects of
ultraviolet radiation for many years.
Polyurethane enamels have a VOC
concentration of 5.0 - 5.5 lbs/gal in
their sprayable form. The high VOC
content of these coatings is offset by
their excellent coverage. Normally,
only two to three coats are needed to
provide a good quality finish. Polyurethane finishes have good flexibility
and can be used over flexible parts
without the addition of flex additives.
Acrylic Urethane Enamel
Acrylic urethanes produce one of
the most durable automotive finishes
available today. They have twice the
durability of polyurethanes, with less
curing time needed to achieve a tack
free finish.
Acrylic urethanes have a relatively
high VOC content (ranging from 5.0 5.5 lbs/gal) in their sprayable form.
Generally, only two coats of these
topcoats are required to produce a
quality finish, reducing the amount
of material needed for the top
coating process.
With acrylic enamels
requiring only twothree coats to provide
adequate coverage,
the VOCs are reduced
by 45% over lacquers
Emission Reduction for Auto Body Shops
39
9: Topcoats
B. Two Stage Basecoat/
Clearcoat Topcoats
It has been estimated that nearly
half of the automobiles on the road
today have a basecoat / clearcoat
finish. The first stage of the finish,
the basecoat, contains the pigments
that give the finish the desired color.
In the case of metallic finishes, the
basecoat also contains the "metallic"
flakes.
VOC content of
waterborne base
coats is relatively
low, ranging from
2.5 - 3.5 lbs/gal
When basecoat / clearcoat systems
first came out, the basecoats were
primarily lacquer based. Today, paint
companies are producing acrylic
enamel, polyester, and urethane
basecoats; all of which have better
metallic control then their lacquer
counterparts. The basecoat is
designed to be easy spraying and
quick drying with excellent metal
control. The quick-drying effect is
designed to keep the base free of dirt
and other contaminants. It also
locks the metallic flakes in position
to achieve a mottle-free finish.
The sole purpose of the basecoat is
to achieve the desired color tint and
metallic appearance. Only two coats
of the base are normally needed to
achieve adequate surface coverage.
Basecoats do not contain the
additives needed to withstand
chemical and ultraviolet deterioration or the chemicals needed to
achieve a high gloss surface.
To protect the basecoat, a durable
clear finish is applied. This clear
coating can often be applied over the
base after only 15 to 30 minutes of
cure time. Commonly the VOC
content of the basecoats range from
6.0 - 7.0 lbs/gal.
40
Clearcoats are typically acrylic
urethane or polyurethane coatings,
although acrylic enamel and lacquer
clears are also available. These
clears are designed to flow upon
application resulting in a smooth,
glass-like finish in as few as two
coats.
VOC content of the clears ranges
from 5.0 - 5.5 lbs/gal in their
sprayable form. Many of the major
paint companies are producing low
VOC clears (3.5 lbs/gal or less) for
use with basecoat / clearcoat
systems. These low VOC, high-solid
clears create a high-gloss finish
with half the materials of a low
solids clear.
Waterborne Basecoat Systems
Waterborne basecoats are
currently being used by a small
number of automobile manufacturing
plants in North America. But with
the implementation of stricter VOC
regulations, these coatings are
expected to gain popularity within
the industry. VOC content of these
waterborne basecoats is relatively
low, ranging from 2.5 - 3.5 lbs/gal in
their sprayable form.
The waterborne technology uses
water as the main solvent, giving
these basecoats low VOC emissions
while retaining low solids content.
The low solids level means greater
metallic control, resulting in a
uniform finish free of mottling.
Some experts note that to achieve
the optimal metallic flake
orientation, the volume of solids in a
coating must be less than 20 percent
by weight. Yet to achieve compliance
within the regulated areas of the U.S.,
the solids volume in solvent based
basecoats must be in excess of 45
percent. Currently, the only way to
Emission Reduction for Auto Body Shops
9: Topcoats
achieve low solids and low VOC
content is through the use
waterborne technology.
Early versions of waterborne
basecoats were very sensitive to
atmospheric conditions in the booth.
Waterborne paints generally contain
less than 10 percent solvents
(excluding water and exempt
solvents) by weight. To achieve
proper crosslinking of the coating,
both the water and the other
solvents must evaporate at the same
time and rate. This will not occur if
the humidity is above the acceptable
range of that coating (generally 65 80 percent). High humidity and/or
low temperatures also increase the
curing time of the finish, and increase
the possibility of runs and sags.
In order to achieve a good quality
finish, humidity and temperature of
the booth must be closely regulated.
In an industrial setting, painting
conditions can be closely monitored
to provide an ideal painting
environment. In the repair industry,
such control can not be adequately
achieved without expensive control
devices. Modern paint booths can
effectively control application
temperature as well as curing
conditions, but booth humidity
remains relatively unchecked.
To help combat the difficulties
associated with the early waterborne
systems, new waterborne
technologies were developed.
Currently, there are two types of
waterborne basecoats being
produced, acrylic latex and urethane
polymer. Both use melamine
formaldehyde polymers as the basic
film former. The addition of these
polymers and glycol ethers has been
instrumental in controlling the flow
of waterborne basecoat finishes
during topcoating operations. Since
the initial stage of curing is no
longer dependent on the rate of
water evaporation, the need for
expensive humidity control devices
are no longer necessary. Adequate
air movement within the spray booth
is necessary to assist in the curing of
the waterborne coating. This has
made waterborne basecoat
technology accessible to the auto
repair industry. These systems are
now being utilized in the regulated
areas of the west coast with some
success. However, waterborne
coatings are still susceptible to cold
weather and must be protected
from freezing during transportation
and storage.
Currently, the only
way to achieve the
low solids and VOC
content is through
the use of
waterborne
technology
Advantages of Waterborne Basecoat Systems
✇ Low VOC content of the sprayable product (2.5 - 3.5).
✇ Good metallic flake orientation properties.
✇ Good atomization properties.
✇ No catalyst is needed for the latex basecoat, only the clear will require
the addition of a catalyst.
✇ No flash time is required between color coats.
41
Emission Reduction for Auto Body Shops
9: Topcoats
B. Two Stage Basecoat/
Clearcoat Topcoats
It has been estimated that nearly
half of the automobiles on the road
today have a basecoat / clearcoat
finish. The first stage of the finish,
the basecoat, contains the pigments
that give the finish the desired color.
In the case of metallic finishes, the
basecoat also contains the "metallic"
flakes.
VOC content of
waterborne base
coats is relatively
low, ranging from
2.5 - 3.5 lbs/gal
When basecoat / clearcoat systems
first came out, the basecoats were
primarily lacquer based. Today, paint
companies are producing acrylic
enamel, polyester, and urethane
basecoats; all of which have better
metallic control then their lacquer
counterparts. The basecoat is
designed to be easy spraying and
quick drying with excellent metal
control. The quick-drying effect is
designed to keep the base free of dirt
and other contaminants. It also
locks the metallic flakes in position
to achieve a mottle-free finish.
The sole purpose of the basecoat is
to achieve the desired color tint and
metallic appearance. Only two coats
of the base are normally needed to
achieve adequate surface coverage.
Basecoats do not contain the
additives needed to withstand
chemical and ultraviolet deterioration or the chemicals needed to
achieve a high gloss surface.
To protect the basecoat, a durable
clear finish is applied. This clear
coating can often be applied over the
base after only 15 to 30 minutes of
cure time. Commonly the VOC
content of the basecoats range from
6.0 - 7.0 lbs/gal.
40
Clearcoats are typically acrylic
urethane or polyurethane coatings,
although acrylic enamel and lacquer
clears are also available. These
clears are designed to flow upon
application resulting in a smooth,
glass-like finish in as few as two
coats.
VOC content of the clears ranges
from 5.0 - 5.5 lbs/gal in their
sprayable form. Many of the major
paint companies are producing low
VOC clears (3.5 lbs/gal or less) for
use with basecoat / clearcoat
systems. These low VOC, high-solid
clears create a high-gloss finish
with half the materials of a low
solids clear.
Waterborne Basecoat Systems
Waterborne basecoats are
currently being used by a small
number of automobile manufacturing
plants in North America. But with
the implementation of stricter VOC
regulations, these coatings are
expected to gain popularity within
the industry. VOC content of these
waterborne basecoats is relatively
low, ranging from 2.5 - 3.5 lbs/gal in
their sprayable form.
The waterborne technology uses
water as the main solvent, giving
these basecoats low VOC emissions
while retaining low solids content.
The low solids level means greater
metallic control, resulting in a
uniform finish free of mottling.
Some experts note that to achieve
the optimal metallic flake
orientation, the volume of solids in a
coating must be less than 20 percent
by weight. Yet to achieve compliance
within the regulated areas of the U.S.,
the solids volume in solvent based
basecoats must be in excess of 45
percent. Currently, the only way to
Emission Reduction for Auto Body Shops
9: Topcoats
achieve low solids and low VOC
content is through the use
waterborne technology.
Early versions of waterborne
basecoats were very sensitive to
atmospheric conditions in the booth.
Waterborne paints generally contain
less than 10 percent solvents
(excluding water and exempt
solvents) by weight. To achieve
proper crosslinking of the coating,
both the water and the other
solvents must evaporate at the same
time and rate. This will not occur if
the humidity is above the acceptable
range of that coating (generally 65 80 percent). High humidity and/or
low temperatures also increase the
curing time of the finish, and increase
the possibility of runs and sags.
In order to achieve a good quality
finish, humidity and temperature of
the booth must be closely regulated.
In an industrial setting, painting
conditions can be closely monitored
to provide an ideal painting
environment. In the repair industry,
such control can not be adequately
achieved without expensive control
devices. Modern paint booths can
effectively control application
temperature as well as curing
conditions, but booth humidity
remains relatively unchecked.
To help combat the difficulties
associated with the early waterborne
systems, new waterborne
technologies were developed.
Currently, there are two types of
waterborne basecoats being
produced, acrylic latex and urethane
polymer. Both use melamine
formaldehyde polymers as the basic
film former. The addition of these
polymers and glycol ethers has been
instrumental in controlling the flow
of waterborne basecoat finishes
during topcoating operations. Since
the initial stage of curing is no
longer dependent on the rate of
water evaporation, the need for
expensive humidity control devices
are no longer necessary. Adequate
air movement within the spray booth
is necessary to assist in the curing of
the waterborne coating. This has
made waterborne basecoat
technology accessible to the auto
repair industry. These systems are
now being utilized in the regulated
areas of the west coast with some
success. However, waterborne
coatings are still susceptible to cold
weather and must be protected
from freezing during transportation
and storage.
Currently, the only
way to achieve the
low solids and VOC
content is through
the use of
waterborne
technology
Advantages of Waterborne Basecoat Systems
✇ Low VOC content of the sprayable product (2.5 - 3.5).
✇ Good metallic flake orientation properties.
✇ Good atomization properties.
✇ No catalyst is needed for the latex basecoat, only the clear will require
the addition of a catalyst.
✇ No flash time is required between color coats.
41
Emission Reduction for Auto Body Shops
9: Topcoats
Advantages, con’t
✇ Waterborne basecoats have superb hiding properties and generally
require only two coats for complete coverage.
✇ Equipment can be cleaned with water instead of solvents.
✇ At least one waterborne paint manufacturer offers a coagulating agent
that will separate the solids from the cleanup water, allowing the water
to be reused while reducing the volume of waste generated.
Disadvantages of Waterborne Basecoat Systems
✇ Current mixing systems need to be modified or replaced to accommodate
waterborne basecoats.
9: Topcoats
D. Recommended Practices for Topcoats
•Mix color coats in-house, making certain the formula for the proper shade
of the specific color code is used. This will help avoid the need for
blending of the finish to achieve a satisfactory color match.
•Keep good records of paint match information, including spray-out cards
and detailed notes.
•Avoid the use of lacquer-based topcoats.
•Choose low VOC topcoats that require fewer than three coats to achieve
adequate coverage (polyurethane or urethane).
•Only apply the number of coats needed to achieve an adequate finish.
•Use high solids, low VOC clears to topcoat color coats.
•The addition of paint additives should be kept to a minimum.
•When available, use waterborne basecoats.
✇ All waterborne products must be transported and stored in such a
manner as to protect them from freezing.
✇ All spray equipment used to apply waterborne coatings will need to be of
a material such as stainless steel to protect against corrosion.
✇ Booth temperature and adequate air movement is essential for achieving
a finish free of runs and sags.
✇ To hasten curing, infrared drying systems or forced air curing systems
may be needed.
✇ Waterborne products are more susceptible to substrate contamination
than are solvent-borne products.
✇ The waste water/paint mixture resulting from equipment cleanup
operations may require more expensive disposal fees than solvent/paint
wastes.
C. Paint Additives
The use of any
additives can
increase VOC
content
Along with the chemical hardeners
and flex additives previously
mentioned, there are many other
paint additives available. These
include flatting compounds,
accelerators, retarders, color blenders
and fisheye eliminators. The
addition of any one of these
additives not only affects the sprayability of the product and the quality
of the finish, it also increases the
VOC content of that system. To keep
VOC emissions low and material
costs down, the use of additives
should be kept to a minimum.
42
43
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
9: Topcoats
Advantages, con’t
✇ Waterborne basecoats have superb hiding properties and generally
require only two coats for complete coverage.
✇ Equipment can be cleaned with water instead of solvents.
✇ At least one waterborne paint manufacturer offers a coagulating agent
that will separate the solids from the cleanup water, allowing the water
to be reused while reducing the volume of waste generated.
Disadvantages of Waterborne Basecoat Systems
✇ Current mixing systems need to be modified or replaced to accommodate
waterborne basecoats.
9: Topcoats
D. Recommended Practices for Topcoats
•Mix color coats in-house, making certain the formula for the proper shade
of the specific color code is used. This will help avoid the need for
blending of the finish to achieve a satisfactory color match.
•Keep good records of paint match information, including spray-out cards
and detailed notes.
•Avoid the use of lacquer-based topcoats.
•Choose low VOC topcoats that require fewer than three coats to achieve
adequate coverage (polyurethane or urethane).
•Only apply the number of coats needed to achieve an adequate finish.
•Use high solids, low VOC clears to topcoat color coats.
•The addition of paint additives should be kept to a minimum.
•When available, use waterborne basecoats.
✇ All waterborne products must be transported and stored in such a
manner as to protect them from freezing.
✇ All spray equipment used to apply waterborne coatings will need to be of
a material such as stainless steel to protect against corrosion.
✇ Booth temperature and adequate air movement is essential for achieving
a finish free of runs and sags.
✇ To hasten curing, infrared drying systems or forced air curing systems
may be needed.
✇ Waterborne products are more susceptible to substrate contamination
than are solvent-borne products.
✇ The waste water/paint mixture resulting from equipment cleanup
operations may require more expensive disposal fees than solvent/paint
wastes.
C. Paint Additives
The use of any
additives can
increase VOC
content
Along with the chemical hardeners
and flex additives previously
mentioned, there are many other
paint additives available. These
include flatting compounds,
accelerators, retarders, color blenders
and fisheye eliminators. The
addition of any one of these
additives not only affects the sprayability of the product and the quality
of the finish, it also increases the
VOC content of that system. To keep
VOC emissions low and material
costs down, the use of additives
should be kept to a minimum.
42
43
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
10. Recommended Approach to Practical
Air Emission Reduction
Spray Equipment
• Determine how much you are willing to spend for spray equipment.
• Determine the types of coatings that will be sprayed through the equipment
and the atomization properties required for their proper application.
• Prior to purchasing any paint gun, consult your paint representative to
determine what type of gun will work best for the products you will be using.
• Contact your paint representative and/or paint gun representative to determine
the fluid tip/air cap combination and gun settings that should be used with the
material being sprayed.
• Choose spray equipment that has the highest transfer efficiency while providing
the required atomization properties within your price range.
Spray Application Techniques
• Use the recommended air pressure and tip sizes for the specific product and
equipment being used.
• Always hold the gun perpendicular to the surface being sprayed, using parallel
strokes. Never arc the gun.
• Feather the trigger at the beginning and end of each pass.
• Use a 50 percent overlap for each pass. This technique may need to be altered
slightly when applying high-metallic, high-solids basecoats, and for some three
stage systems.
• When painting small and medium sized panels, make each pass the full length
of the panel.
• With larger panels, use a comfortable stroke, with a 4 - 5 " overlap of the
strokes.
• If blending is necessary, keep the blend area as small as possible without
jeopardizing the appearance of the blend.
• Spray the border edges of the substrate first (banding). This will assure all
edges are covered without extending the spray pattern well beyond the borders
of the object.
• Use color hiding power labels to determine the thickness of the applied paint
film. These markers will also indicate when adequate coverage has been
achieved.
45
Emission Reduction for Auto Body Shops
10. Recommended Approach to Practical
Air Emission Reduction
Spray Equipment
• Determine how much you are willing to spend for spray equipment.
• Determine the types of coatings that will be sprayed through the equipment
and the atomization properties required for their proper application.
• Prior to purchasing any paint gun, consult your paint representative to
determine what type of gun will work best for the products you will be using.
• Contact your paint representative and/or paint gun representative to determine
the fluid tip/air cap combination and gun settings that should be used with the
material being sprayed.
• Choose spray equipment that has the highest transfer efficiency while providing
the required atomization properties within your price range.
Spray Application Techniques
• Use the recommended air pressure and tip sizes for the specific product and
equipment being used.
• Always hold the gun perpendicular to the surface being sprayed, using parallel
strokes. Never arc the gun.
• Feather the trigger at the beginning and end of each pass.
• Use a 50 percent overlap for each pass. This technique may need to be altered
slightly when applying high-metallic, high-solids basecoats, and for some three
stage systems.
• When painting small and medium sized panels, make each pass the full length
of the panel.
• With larger panels, use a comfortable stroke, with a 4 - 5 " overlap of the
strokes.
• If blending is necessary, keep the blend area as small as possible without
jeopardizing the appearance of the blend.
• Spray the border edges of the substrate first (banding). This will assure all
edges are covered without extending the spray pattern well beyond the borders
of the object.
• Use color hiding power labels to determine the thickness of the applied paint
film. These markers will also indicate when adequate coverage has been
achieved.
45
Emission Reduction for Auto Body Shops
10: Recommended Approach to Practical Air
Emission Reduction
Equipment Cleaning
• Use an air powered mechanical gun cleaning system.
• Use low VOC cleaning solvents.
• If cleaning guns manually, spray into an enclosed backdrop to retain atomized
solvents.
• If necessary, use a broom straw, cleaning broach or a soft wood toothpick to clear
passageways. Never use metal objects.
Surface Prep
• Always wash dirt and grime from the vehicle using water or a soap and water
mixture.
• Use waterborne cleaners when possible.
• If, due to heavy contamination, waterborne cleaners prove unsatisfactory, use
solvent-based cleaners for the initial cleaning. For secondary cleaning
operations, use the waterborne products.
• If waterborne cleaners prove unsatisfactory due to substrate make-up, use
solvent-based cleaners sparingly.
• Keep solvent laden dirty rags in a closed container.
• Keep solvent containers closed when not in use.
• If possible, avoid operations that would necessitate multiple prepaint cleaning
operations.
Prep Coats
• Use versatile products such as epoxy primers or self-etching primers. The use
of these products may alleviate the need for additional surface coating
operations such as primer-surfacing or primer-sealing.
10: Recommended Approach to Practical Air
Emission Reduction
Primer-surfacers con’t
• If a colored sealer is not used, make sure the primer-surfacer is a color that can
easily be covered with the desired topcoat.
Primer Sealers
• Use low VOC primer-sealers such as single component waterborne or
waterborne epoxy primers.
• The use of low VOC urethane primer-sealers would also be an acceptable
choice.
• Always choose a color of primer-sealer that can be easily covered by the
topcoat to be sprayed or choose a tintable primer-sealer and tint it to an easily
covered shade.
Sealers
• Chose the proper sealer for each specific job.
• If filling capabilities are required, use a primer-sealer in place of a sealer.
• Always choose a primer-sealer of a color that can be easily covered with the
coating to be sprayed, or choose a tintable primer-sealer.
Topcoats
• Mix color coats in-house, making certain the formula for the proper shade of
the specific color code is used. This will help avoid the need for the blending of
the finish to achieve a satisfactory color match.
• Keep good records of paint match information, including spray-out cards and
detailed notes.
• Avoid the use of lacquer-based topcoats.
• If a self-etching primer or epoxy primer is not desirable, use a wash-primer or
metal conditioner, conversion coating system.
• Choose low VOC topcoats that require fewer than three coats to achieve
adequate coverage (polyurethane or urethane).
• Avoid high VOC content zinc phosphate primers.
• Apply only the number of coats needed to achieve an adequate finish.
Primer-Surfacers
• Use a properly operating primer gun with the correct fluid tip/air cap
combination for your particular type of primer-surfacer.
• Use high solids, low VOC clears to topcoat color coats.
• Keep addition of paint additives to a minimum.
• When available, use waterborne basecoats.
• Use low VOC, waterborne primer-surfacer products.
• If the curing time of waterborne products proves unsatisfactory, consider the
use of versatile urethane primers.
• To reduce VOC emissions, limit material costs, and achieve a better quality
product, make sure body work is done in such a manner as to require only a
minimal amount of primer-surfacer.
46
47
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
10: Recommended Approach to Practical Air
Emission Reduction
Equipment Cleaning
• Use an air powered mechanical gun cleaning system.
• Use low VOC cleaning solvents.
• If cleaning guns manually, spray into an enclosed backdrop to retain atomized
solvents.
• If necessary, use a broom straw, cleaning broach or a soft wood toothpick to clear
passageways. Never use metal objects.
Surface Prep
• Always wash dirt and grime from the vehicle using water or a soap and water
mixture.
• Use waterborne cleaners when possible.
• If, due to heavy contamination, waterborne cleaners prove unsatisfactory, use
solvent-based cleaners for the initial cleaning. For secondary cleaning
operations, use the waterborne products.
• If waterborne cleaners prove unsatisfactory due to substrate make-up, use
solvent-based cleaners sparingly.
• Keep solvent laden dirty rags in a closed container.
• Keep solvent containers closed when not in use.
• If possible, avoid operations that would necessitate multiple prepaint cleaning
operations.
Prep Coats
• Use versatile products such as epoxy primers or self-etching primers. The use
of these products may alleviate the need for additional surface coating
operations such as primer-surfacing or primer-sealing.
10: Recommended Approach to Practical Air
Emission Reduction
Primer-surfacers con’t
• If a colored sealer is not used, make sure the primer-surfacer is a color that can
easily be covered with the desired topcoat.
Primer Sealers
• Use low VOC primer-sealers such as single component waterborne or
waterborne epoxy primers.
• The use of low VOC urethane primer-sealers would also be an acceptable
choice.
• Always choose a color of primer-sealer that can be easily covered by the
topcoat to be sprayed or choose a tintable primer-sealer and tint it to an easily
covered shade.
Sealers
• Chose the proper sealer for each specific job.
• If filling capabilities are required, use a primer-sealer in place of a sealer.
• Always choose a primer-sealer of a color that can be easily covered with the
coating to be sprayed, or choose a tintable primer-sealer.
Topcoats
• Mix color coats in-house, making certain the formula for the proper shade of
the specific color code is used. This will help avoid the need for the blending of
the finish to achieve a satisfactory color match.
• Keep good records of paint match information, including spray-out cards and
detailed notes.
• Avoid the use of lacquer-based topcoats.
• If a self-etching primer or epoxy primer is not desirable, use a wash-primer or
metal conditioner, conversion coating system.
• Choose low VOC topcoats that require fewer than three coats to achieve
adequate coverage (polyurethane or urethane).
• Avoid high VOC content zinc phosphate primers.
• Apply only the number of coats needed to achieve an adequate finish.
Primer-Surfacers
• Use a properly operating primer gun with the correct fluid tip/air cap
combination for your particular type of primer-surfacer.
• Use high solids, low VOC clears to topcoat color coats.
• Keep addition of paint additives to a minimum.
• When available, use waterborne basecoats.
• Use low VOC, waterborne primer-surfacer products.
• If the curing time of waterborne products proves unsatisfactory, consider the
use of versatile urethane primers.
• To reduce VOC emissions, limit material costs, and achieve a better quality
product, make sure body work is done in such a manner as to require only a
minimal amount of primer-surfacer.
46
47
Emission Reduction for Auto Body Shops
Emission Reduction for Auto Body Shops
11. What to Expect in
the Future
T
he automotive refinishing
industry has undergone many
significant changes in the last ten
years, with even greater changes
anticipated within the next decade.
The Clean Air Act Amendments
require implementation of new
stringent emission control and
permitting requirements within the
next ten years. Although it is not yet
clear what specific regulations are in
store for the automotive refinishing
industry, it is clear that some form of
emission regulations will be imposed.
Impending regulations are already
causing many changes within the
paint manufacturing and application
equipment industries.
Paint manufacturers are focusing
their efforts on the development of
paints and primers that will meet
the rigid standards of the future.
VOC contents of topcoats will
probably be limited to 5.0 lbs/gal or
less, while undercoats may be limited
to as low as 3.5 lbs/gal. Paint manufacturers will continue emphasizing
development of waterborne and highsolids paints and primers.
Waterborne paints will probably
be limited to basecoats which will
require the application of a urethane
clearcoat. The use of glycol ethers,
esters, ester alcohols and water as
solvents for paint products will
continue to increase. Other high
solvency products such as propylene
glycol and methyl butyl ethers will
also gain popularity with paint
manufacturers.
High viscosity, high solids paints
and primers may require modification of current paint practices
within the refinishing industry.
Paint-heaters may be essential in
every paint shop to lower the
viscosity of the high-solids solventbased paints and primers prior to
spraying. Heaters are not effective
with waterborne paints due to their
lack of effect on these products'
viscosity.
The spray equipment used by the
typical paint shop will be of the
HVLP variety. High transferefficient spray equipment will
continue to improve, providing the
technician with better atomization
and metallic control.
Recently, a new paint system has
been developed using super-critical
carbon dioxide (CO 2) in place of
solvents to lower the viscosity of the
coating. These systems reduce VOC
emissions from 25 percent to as
much as 80 percent, depending on
the coating used. Currently, the use
of these systems is limited to
industrial painting; the finish quality
needed for the application of
automotive finishes has yet to be
achieved. As the technology improves
and investment costs lower, CO2
systems may be used on a limited
scale for auto refinishing operations.
The spray
equipment used by the
typical paint shop
will be of the HVLP
variety.
Automobile refinishers will be
unable to rely solely on low VOC
products and high transfer efficient
spray equipment to reduce VOC
emissions. Employers will also need
to train their painters and prep
technicians in the proper use of all
existing and new equipment and
products entering the market place.
Spray paint techniques must also be
49
Emission Reduction for Auto Body Shops
11. What to Expect in
the Future
T
he automotive refinishing
industry has undergone many
significant changes in the last ten
years, with even greater changes
anticipated within the next decade.
The Clean Air Act Amendments
require implementation of new
stringent emission control and
permitting requirements within the
next ten years. Although it is not yet
clear what specific regulations are in
store for the automotive refinishing
industry, it is clear that some form of
emission regulations will be imposed.
Impending regulations are already
causing many changes within the
paint manufacturing and application
equipment industries.
Paint manufacturers are focusing
their efforts on the development of
paints and primers that will meet
the rigid standards of the future.
VOC contents of topcoats will
probably be limited to 5.0 lbs/gal or
less, while undercoats may be limited
to as low as 3.5 lbs/gal. Paint manufacturers will continue emphasizing
development of waterborne and highsolids paints and primers.
Waterborne paints will probably
be limited to basecoats which will
require the application of a urethane
clearcoat. The use of glycol ethers,
esters, ester alcohols and water as
solvents for paint products will
continue to increase. Other high
solvency products such as propylene
glycol and methyl butyl ethers will
also gain popularity with paint
manufacturers.
High viscosity, high solids paints
and primers may require modification of current paint practices
within the refinishing industry.
Paint-heaters may be essential in
every paint shop to lower the
viscosity of the high-solids solventbased paints and primers prior to
spraying. Heaters are not effective
with waterborne paints due to their
lack of effect on these products'
viscosity.
The spray equipment used by the
typical paint shop will be of the
HVLP variety. High transferefficient spray equipment will
continue to improve, providing the
technician with better atomization
and metallic control.
Recently, a new paint system has
been developed using super-critical
carbon dioxide (CO 2) in place of
solvents to lower the viscosity of the
coating. These systems reduce VOC
emissions from 25 percent to as
much as 80 percent, depending on
the coating used. Currently, the use
of these systems is limited to
industrial painting; the finish quality
needed for the application of
automotive finishes has yet to be
achieved. As the technology improves
and investment costs lower, CO2
systems may be used on a limited
scale for auto refinishing operations.
The spray
equipment used by the
typical paint shop
will be of the HVLP
variety.
Automobile refinishers will be
unable to rely solely on low VOC
products and high transfer efficient
spray equipment to reduce VOC
emissions. Employers will also need
to train their painters and prep
technicians in the proper use of all
existing and new equipment and
products entering the market place.
Spray paint techniques must also be
49
Emission Reduction for Auto Body Shops
11: What to Expect in the Future
improved to reduce overspray to
reduce material waste and VOC
emissions. This will require painters
to have additional training in proper
spraying techniques using the new
high transfer spray equipment.
It will take the efforts of all paint
related industries to provide
adequate reduction of VOCs and
HAPs. Changes in coating products,
spray equipment and application
techniques will all be met with some
resistance. But with continued
cooperation and education, harmful
VOC and HAP emissions from
refinishing operations will be dramatically reduced, creating a cleaner
and healthier environment for all.
Laser TM
Touch
The Iowa Waste Reduction Center has developed and
TM
patented the Laser Touch targeting system to help
improve transfer efficiency, and reduce overspray and
TM
material consumption. The Laser Touch is designed
to provide spray technicians with a “real-time” means of
assessing their spray technique and improving their spray performance. It
uses a split laser beam image to provide the spray gun operator with a
visual indication of gun-to-part distance, gun angle and targeting.
TM
The Laser Touch
has proved to be the most well received and productive
training tool used in the Spray Technique Analysis and Research program.
TM
STAR trainees using the Laser Touch have shown dramatic
improvements in maintaining a consistent
spray distance, proper gun angle, uniform
coating thickness and improved transfer
efficiency. The following comments are
representative of statements made by
TM
Laser Touch users:
• “I cannot believe my spray distance
varied that much, this device helps me
immediately in keeping me consistent.”
• “Quite frankly, it’s perhaps one of the
biggest money saving devices that we
have ever seen come about it this
industry.”
• “This is great for both experienced
painters as well as the beginners.”
For more information on the Laser
TM
call the IWRC at 319-273-8905.
Touch
50
Emission Reduction for Auto Body Shops
11: What to Expect in the Future
improved to reduce overspray to
reduce material waste and VOC
emissions. This will require painters
to have additional training in proper
spraying techniques using the new
high transfer spray equipment.
It will take the efforts of all paint
related industries to provide
adequate reduction of VOCs and
HAPs. Changes in coating products,
spray equipment and application
techniques will all be met with some
resistance. But with continued
cooperation and education, harmful
VOC and HAP emissions from
refinishing operations will be dramatically reduced, creating a cleaner
and healthier environment for all.
Laser TM
Touch
The Iowa Waste Reduction Center has developed and
TM
patented the Laser Touch targeting system to help
improve transfer efficiency, and reduce overspray and
TM
material consumption. The Laser Touch is designed
to provide spray technicians with a “real-time” means of
assessing their spray technique and improving their spray performance. It
uses a split laser beam image to provide the spray gun operator with a
visual indication of gun-to-part distance, gun angle and targeting.
TM
The Laser Touch
has proved to be the most well received and productive
training tool used in the Spray Technique Analysis and Research program.
TM
STAR trainees using the Laser Touch have shown dramatic
improvements in maintaining a consistent
spray distance, proper gun angle, uniform
coating thickness and improved transfer
efficiency. The following comments are
representative of statements made by
TM
Laser Touch users:
• “I cannot believe my spray distance
varied that much, this device helps me
immediately in keeping me consistent.”
• “Quite frankly, it’s perhaps one of the
biggest money saving devices that we
have ever seen come about it this
industry.”
• “This is great for both experienced
painters as well as the beginners.”
For more information on the Laser
TM
call the IWRC at 319-273-8905.
Touch
50
Emission Reduction for Auto Body Shops
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