User Manual

User Manual
User Manual
& Product Guide
Our Epoxies
The 105 System
Metering Pumps
Reinforcing Materials
Application Tools
Specialty Items
Skin Protection
Epoxy Handling
Basic Techniques
Problem Solver
Product Guide
User Manual
& Product Guide
WEST SYSTEM Epoxy is a versatile, high-quality,
two-part epoxy that is easily modified for a wide
range of coating and adhesive applications. It is
used for construction and repairs requiring superior
moisture resistance and high strength. It bonds to
fiberglass, wood, metal, plastics, fabrics, and other
composite materials, and is especially suited for
marine applications.
This manual is designed to help you become
familiar with WEST SYSTEM products and use
them effectively.
It’s much more difficult
balancing all of the physical
Performance Properties
and mechanical properties
necessary for a versatile, highCreep
quality marine epoxy. Defining
an epoxy’s performance criteria,
and designing a formula to meet
those criteria requires good chemistry, rigorous test programs, skillful shop work and direct experience
with today’s high-performance boats and other composite structures.
•The User Manual provides information about safety,
handling and the basic techniques of epoxy use.
Understanding these basic techniques will allow you
to tailor WEST SYSTEM products to your exact repair
and construction needs. These techniques are used
in a wide range of repair and building procedures
such as those described in detail in WEST SYSTEM
instructional publications and DVDs.
All epoxies are not created equal. Epoxy brands can vary widely in
their formulations, quality of raw materials and their suitability for
marine environments. It’s easy to market an off-the-shelf industrial
epoxy product as a marine epoxy,
or formulate an epoxy with one
or two favorable characterisToughness
tics, while sacrificing other
important characteristics.
Reliability and Performance
•The Product Guide gives you complete descriptions
of WEST SYSTEM products, including selection and
coverage guides to help you choose the most appropriate products and product sizes for your project.
WEST SYSTEM Epoxy was created by Gougeon Brothers–sailors,
builders and formulators who know the engineering and the chemistry
required for high-performance composite structures. We have maintained that performance driven development of marine epoxies since
the company was founded in 1969, continually formulating, testing
and improving WEST SYSTEM Resins and Hardeners and developing
specialty epoxies to produce the most reliable and well-balanced
epoxy systems available.
WEST SYSTEM products are available from quality
marine chandleries and hardware outlets in many
areas. For the name of the WEST SYSTEM dealer
nearest you, or for additional technical, product, or
safety information contact Gougeon Brothers, Inc. or
Our resin and hardener formulas, ingredients and combinations are
tested to compare fatigue strength, compression strength, glass transition temperature, and peak exotherm. Qualified samples undergo
additional tests for hardness, tensile strength, tensile elongation,
tensile modulus, flexural strength, flexural modulus, heat deflection
temperature, impact resistance and moisture exclusion effectiveness. This level of testing ensures that any change in a formula
•The Problem Solver will help you identify and
prevent potential problems associated with
using epoxy.
WEST SYSTEM User Manual & Product Guide ||
Product Guide
will improve one or more of a product’s characteristics without diminishing
any characteristics.
As an ISO 9001 certified company, Gougeon Brothers has numerous protocols in place to ensure the quality of every batch of epoxy we make. We are
dedicated to providing the highest quality product to meet the standards our
customers expect.
Comprehensive Testing
Good science and comprehensive testing are essential not only for the development of improved epoxy formulations, but also for the development of much better
construction and repair methods. In addition to the tests conducted to support
in-house product development, our materials test lab also conducts testing to
support our outside builders, designers, and government organizations in the engineering of epoxy composite structures.
Aside from performing a battery of standard ASTM tests, we have developed
new testing methods to evaluate adhesives and composites. Some of these
tests, like our patented Hydromat Panel test, have become industry standards.
This test uses a special fixture in one of the lab’s MTS™ test machines to
simulate the pressure loads a section of a hull would endure in a lifetime on
the water. In 1999, the American Society for Testing and Materials approved
the Hydromat test as an official ASTM standard (D6416). This unique testing
program is used by designers and builders around the world to evaluate various
combinations of sandwich composite materials and epoxy formulations and
ultimately build lighter, stronger, safer structures.
The information provided by a comprehensive test program, along with our own
building experience, and feedback from our customers contributes to a data
base on epoxies and epoxy composites that has been growing since 1969. This
knowledge is invaluable for achieving the proper balance of properties required
for a versatile, high-quality marine epoxy, and assures that the building and
repair information provided by Gougeon Brothers is up-to-date and reliable.
Technical Support
To help you make the most of WEST SYSTEM Epoxy’s balanced performance and
versatility, Gougeon Brothers provides you with one other important ingredient—knowledge. Whether your project is large or small, WEST SYSTEM technical publications and videos offered in this guide provide detailed procedures
and instructions for specific repair and construction applications.
We are always interested in your views and welcome suggestions about our
products and service. We encourage you to call or write with comments on
WEST SYSTEM products and their use.
For the most current product selection visit
Because Gougeon Brothers, Inc. cannot control how its products will be used, it makes no warranties,
either expressed or implied, including no warranties of merchantability and fitness for purpose intended.
Gougeon Brothers, Inc. will not be liable for incidental or consequential damages.
|| WEST SYSTEM User Manual & Product Guide
Gougeon Brothers, Inc.
P.O. Box 908
Bay City, MI 48707 USA
Product Guide
Good science
and comprehensive testing
are essential
for the development and
improvement of
epoxy formulations, and for
the development of much
better construction and repair
WEST SYSTEM User Manual & Product Guide ||
Product Guide
Our Epoxies
Based on 105 Epoxy Resin,
West System Epoxy is a versatile
low-viscosity epoxy system. It is
used for boat building, composite
construction and repairs that
require high-strength, waterproof
coating, bonding, and filling. It
readily wets out fabrics and porous
materials, and is easily modified for
a wide range of working conditions
and applications. West System
Epoxy is the world’s most reliable
and widely used marine epoxy.
G/flex Epoxy is an
easy-to-use, toughened
epoxy designed to make
structural bonds that
absorb the stresses of
extraordinary expansion, contraction, shock,
and vibration. Excellent
adhesive properties
allow you to glue a wide
range of materials.
|| WEST SYSTEM User Manual & Product Guide
Six10 Adhesive gives
you the strength and
reliability of a two-part
with the convenience of
a single part product.
Six10 is dispensed with
a standard caulking
gun. Non-sagging Six10
bonds tenaciously to
wood, metals, fiberglass
and concrete.
G/5 Five-Minute Adhesive is an easy-to-use
epoxy for quick repairs
and general bonding.
It is a durable, water
resistant adhesive that
bonds to most materials. Use it for making
jigs and fixtures quickly.
An exceptionally strong
and cost effective fiveminute epoxy.
Product Guide
G/flex® Epoxy
G/flex Epoxies are toughened, resilient two-part
epoxies engineered for a superior grip to metals,
plastics, glass, masonry, fiberglass, and wet and
difficult-to-bond woods. Make structural bonds
that absorb the stresses of expansion, contraction,
shock and vibration. Easy-to-use 1:1 mix ratio gives
you 46 minute pot life and a long open, or working,
time of 75 minutes at 72°F. Reaches an initial cure
in 3–4 hours and a workable cure in 7–10 hours.
Available in two consistencies:
G/flex 650 Epoxy is a versatile easily-modified liquid epoxy. It is packaged in the
Aluminum Boat Repair Kit or individually.
650-8 4 fl oz resin, 4 fl oz hardener.
650-32 16 fl oz resin, 16 fl oz hardener.
Larger sizes available.
G/flex 655 Epoxy Adhesive is a convenient pre-thickened epoxy. It is packaged in
the Plastic Boat Repair Kit or individually.
655-8 4.2 fl oz resin, 4.2 fl oz hardener.
655-2QT 1 qt resin, 1 qt hardener.
655-2G 1 gal resin, 1 gal hardener.
Larger sizes available.
Six10® Epoxy Adhesive
A two-part thickened epoxy adhesive in a convenient, self-metering cartridge. For permanent,
waterproof, structural gap-filling and gluing. Bonds
to wood, fiberglass, metals and masonry. With
the included 600 Static Mixer attached you can
dispense fully mixed adhesive right where you need
it using a standard caulking gun. Trim the mixer tip
to suit your job. A 1/8" diameter tip opening will give
you a bead of adhesive about a 40’ long. Working
time is 42 minutes at 72°F, cures to a solid in 5–6
hours and takes high loads in 24 hours.
610 190 ml resin/hardener cartridge.
600-2 Static Mixers only, 2 ea.
600-12 Static Mixers only, 12 ea.
G/5® Five-Minute Adhesive
An easy to use, fast curing epoxy system for
quick repairs, tooling and general bonding. It
is a strong, water resistant adhesive that can
be thickened as necessary with WEST SYSTEM
fillers. Bonds to wood, fiberglass and metal.
1:1 mixture, no pumps are required. Cures in
3-5 minutes at 72°F.
Repair Kits
105-K Fiberglass Boat Repair Kit
Repair cracks and scrapes, gelcoat blisters,
loose hardware, delaminated decks and
panels, damaged keels and holes up to 1"
diameter in solid laminates up to ¼"-thick and
smaller holes in thicker laminates. Includes
complete, illustrated instructions.
105-K 1 Kit.
650-K Aluminum Boat Repair Kit
Repair the most common problem with
aluminum boats and canoes—leaking
seams and rivets. Includes complete, illustrated instructions.
650-K 1 Kit.
655-K Plastic Boat Repair Kit
Repair splits, cracks and small holes in
plastic canoes, kayaks and other small boats.
Includes instructions for patching air leaks,
re-bonding attachment points, repairing
delaminated transoms and damaged floors in
inflatable boats. Includes complete, illustrated instructions.
655-K 1 Kit.
101 Handy Repair Pack
Everything you need to complete small repairs
around the boat, shop or home. The Handy
Repair Pack contains two WEST SYSTEM 105
Epoxy Resin/205 Fast Hardener packets, and
enough adhesive filler to complete a variety of
coating and bonding operations. Also included
are a 2"×10" piece of 9 oz fiberglass tape
(useful for patching, reinforcing or abrasion
resistance), an application brush, mixing stick,
pipe cleaner, two cleaning pads and complete
instructions. The components can be mixed in
the disposable package.
101 1 Kit.
101-T Resin/Hardener Packets
101-T Six resin/hardener packets only. Each
pre-measured packet contains 16g of 105
Resin and 3.2g of 205 Fast Hardener (19.2g
or 0.56 fl oz of mixed epoxy).
101-T Pack of 6.
865-4 4 fl oz resin, 4 fl oz hardener.
865-16 16 fl oz resin, 16 fl oz hardener.
Larger sizes available.
WEST SYSTEM User Manual & Product Guide ||
Product Guide
The 105 System
West System Epoxy products make up a versatile epoxy
system that can be used for everything from basic long-lasting
repairs to the construction of high-performance composites.
West System Epoxy will cure to a high-strength plastic solid at 72°F, when
you mix specific proportions of liquid epoxy resin and hardener. This plastic
adheres to a wide range of materials, making it ideal for projects that require
water and chemical resistance, and strong physical properties for structural
bonding. Select from a range of hardeners and additives that allow you to
tailor the mixture’s handling characteristics and cured physical properties to
suit your working conditions and specific coating or bonding application.
|| WEST SYSTEM User Manual & Product Guide
Product Guide
page 8
Special Clear
Lowest Weight
page 13
Light Structural
Extra Slow
Colloidal Silica
Filleting Blend
Wood Toned
High Load
General Wood
Aluminum Powder
Blister Resistance
and GAP
Pigmented Undercoat
General Structural
Graphite Powder
Barrier Coat
FILLERS page 10
Start with 105 Epoxy Resin,
the basic ingredient of all
compounds. Use 300 Mini
Pumps for convenient and
accurate metering.
Mix with one of four WEST
SYSTEM hardeners.
Select a hardener for
its intended use and
for the cure speed best
suited for your job in the
temperature range in
which you are working.
Add one of six WEST
SYSTEM fillers to thicken
the mixture as needed.
Select a filler for its
handling characteristics or
cured physical properties.
Or, add one of four WEST
SYSTEM additives to
provide specific coating
Abrasion Resistance
For excellent results, in addition
to proper product selection, it is
important to know best practices
for epoxy use, know how to
use epoxy safely and have the
proper tools for your project.
Reinforcing Materials
We offer a range of detailed publications that can help
you get started. Our publications include manuals on
Fiberglass Boat Repair and Maintenance, Wooden Boat
Restoration and Repair, and Boat construction. We also
offer a How-To DVD which covers everything from basic
epoxy handling to advanced epoxy repair techniques.
(See detailed publication descriptions on page 18)
Whether repairing a fiberglass boat or building a
wooden canoe, reinforcing materials are an important
part of many building and repair projects.
(See detailed reinforcing descriptions on page 14)
Application Tools
Roller covers, mixing sticks, mixing cups and plastic
spreaders are just a few of the tools we offer that
make working with epoxy easier.
(See detailed tool descriptions on page 15)
Skin Protection
Our personal protective clothing is made out of
microporous film laminate material which provides a
superior combination of strength, barrier protection,
and breathability.
(See detailed skin protection descriptions on page 17)
WEST SYSTEM User Manual & Product Guide ||
Product Guide
105 Epoxy Resin®
105 Resin is a clear, low-viscosity liquid epoxy resin. Formulated for use with
one of four WEST SYSTEM hardeners, it can be cured in a wide temperature
range to form a high-strength solid with excellent moisture resistance.
105 Epoxy Resin, when mixed at the proper ratio with a WEST SYSTEM hardener, is an excellent adhesive. It is designed specifically to wet out and bond to
wood fiber, fiberglass, reinforcing fabrics, foam other composite materials, and
a variety of metals. 105 Resin-based epoxy will bridge gaps and fill voids when
modified with WEST SYSTEM fillers and can be sanded and shaped when cured.
With roller applications, it has excellent thin film characteristics, allowing
it to flow out and self-level without “fish-eyeing.” Multiple coats of a 105
epoxy create a superior moisture barrier and a tough, stable base for paints
and varnishes.
105 Resin is formulated without volatile solvents and does not shrink after
curing. It has a relatively high flash point and no strong solvent odor, making it
safer to work with than polyester or vinylester resins. Resin viscosity is approximately 1000 centipoise (cP) at 72°F (22°C).
Refer to the Hardener Selection Guide for the most appropriate hardener for
your application.
WEST SYSTEM Epoxy resin and hardeners
are packaged in three “Group Sizes.” For
each container size of resin, there is a
corresponding sized container of hardener.
When purchasing resin and hardener, be sure
both containers are labeled with the same
Group Size letter (A, B or C).
Estimated Epoxy Coverage for Fabric Application
Below is an estimation of how much epoxy is needed wet
out 1 sq. ft. of fiberglass cloth and apply two fill coats.
Fabric Product Number
Fabric weight
per yd2
Mixed Epoxy Needed
4 oz
1.4 fl. oz.
6 oz
1.61 fl. oz.
729, 731, 732, 733
9 oz
1.94 fl. oz.
10 oz
2.05 fl. oz.
727, 737
17 oz
2.81 fl. oz.
23.8 oz
3.55 fl. oz.
(see page 24)
* Includes 15% waste factor.
Resin/Hardener Group
Resin Quantity
Hardener Quantity
Mixed quantity
Saturation coat
porous surfaces
Buildup coats
non-porous surfaces
205-A or 206-A
.43 pt (206 ml)
.47 lb
1.2 qt (1.15 L)
2.87 lb
90–105 ft2
120–135 ft2
(11–12.5 m2)
207-SA or 209-SA
.66 pt (315 ml)
.70 lb
1.3 qt (1.26 L)
3.1 lb
90–105 ft2
(9–10 m2)
120–135 ft2
(11–13 m2)
205-B or 206-B
.86 qt (814 ml)
1.86 lb
1.2 gal (4.55 L)
11.36 lb
350–405 ft2
(32–37 m2)
462–520 ft2
(43–48 m2)
207-SB or 209-SB
1.32 qt (1.23 L)
2.75 lb
1.3 gal (4.98 L)
12.25 lb
370–430 ft2
(35–40 m2)
490–550 ft2
(45–50 m2)
205-C or 206-C
.94 gal (3.58 L)
8.20 lb
5.29 gal (20 L)
50.02 lb
1530–1785 ft2
(142–165 m2)
2040–2300 ft2
(190–213 m2)
207-SC or 209-SC
1.45 gal (5.49 L)
12.0 lb
5.8 gal (21.9 L)
53.82 lb
1675–1955 ft2
(155–180 m2)
2235–2520 ft2
(207–233 m2)
1 qt (946 ml)
2.40 lb
.98 gal (3.74 L)
9.50 lb
4.35 gal (16.47 L)
41.82 lb
|| WEST SYSTEM User Manual & Product Guide
Product Guide
Hardener Selection
Select a hardener for its
intended use and for the
cure speed best suited
for your job in the temperature range in which
you are working.
CURE SPEEDS at room temp.*
Room Temperature
100g cupful
thin film
thin film
Fast cure—General bonding, fabric
application and barrier coating
Slow cure—General bonding, fabric
application and barrier coating
Extra Slow cure—General bonding,
fabric application, barrier coating
Clear fabric application, clear
coating and general bonding.
*Epoxy cures faster in warmer temperatures and in thicker applications—Epoxy cures slower in cooler temperatures and in thinner applications.
205 Fast Hardener®
206 Slow Hardener®
207 Special Clear Hardener™
205 Fast Hardener is formulated for general
coating and bonding applications at lower
temperatures and to produce a rapid cure
that develops its physical properties quickly
at room temperature. 105/205 forms a highstrength, moisture-resistant solid with excellent
bonding and barrier coating properties. Not
intended for clear coating.
206 Slow Hardener is formulated for general
coating and bonding applications when
extended working and cure time are needed
or to provide adequate working time at higher
temperatures. 105/206 forms a high-strength,
moisture-resistant solid with excellent bonding
and barrier coating properties. Not intended
for clear coating.
207 Special Clear Hardener was developed
for coating and fiberglass cloth application
where an exceptionally clear, moisture-resistant, clear carbon fiber or natural wood finish
is desired. 207 Hardener will not blush or turn
cloudy in humid conditions. Thin film applications roll out and tip off smoothly, requiring
less sanding in preparation for finish coatings.
Mix ratio
5 parts resin : 1 part hardener
Pot life at 72°F (22°C)
9 to 12 min.
Cure to a solid state
6 to 8 hrs
Cure to working strength
1 to 4 days
Min. recommended temp.
40°F (4°C)
Mix ratio
5 parts resin : 1 part hardener
Pot life at 72°F (22°C)
20 to 25 min.
Cure to a solid state
10 to 15 hrs
Cure to working strength
1 to 4 days
Min. recommended temp.
60°F (16°C)
Professional and first-time builders like 207
because it is reliable and easy to use. Three
coats or more can be applied in one day
without additional surface preparation. Fewer
coats are required to fill fiberglass weave and
in most cases the final coating can be sanded
the following day. Builders also appreciate the
excellent fiberglass wet-out characteristics
achieved with 105/207, yet it won’t drain from
vertical surfaces like the very slow curing,
low-viscosity epoxies.
Storage/Shelf Life
Store at room temperature. Keep
containers closed to prevent
contamination. With proper storage,
resin and hardeners should remain
usable for many years. After a
long storage, verify the metering
accuracy of the pumps. Mix a small
test batch to assure proper curing.
Over time, 105 Resin will thicken
slightly and will therefore require
extra care when mixing. Repeated
freeze/thaw cycles during storage
may cause crystallization of 105
Resin. Warm resin to 125°F and stir
to dissolve crystals.
Hardeners may darken with age, but
physical properties are not affected
by color. If clear finishing, be aware
of a possible color shift if very old
and new hardeners are used on the
same project.
209 Extra Slow Hardener™
209 Extra Slow Hardener is formulated for
general coating and bonding applications in
extremely warm and/or humid conditions or
when extended working time is desired at room
temperature. Provides approximately twice the
working time of 206 Slow Hardener. 105/209
forms a high-strength, moisture-resistant solid
with excellent bonding and barrier coating
properties. Not intended for clear coating.
105/207 has strong physical properties, so it
can be used as a structural adhesive for gluing
and laminating. It has excellent compatibility
with paints and varnishes. An ultraviolet
Mix ratio
3 parts resin : 1 part hardener inhibitor in 207 helps provide a beautiful, long
Pot life at 72°F (22°C)
40 to 50 min
lasting finish when used with quality UV-filat 95°F (35°C)
15 to 20 min
tering top coat.
Cure to a solid state
at 72°F (22°C)
at 95°F (35°C)
Cure to working strength
at 72°F (22°C)
Min. recommended temp.
20 to 24 hrs
6 to 8 hrs
4 to 9 days
70°F (21°C)
Mix ratio
3 parts resin : 1 part hardener
Pot life at 72°F (22°C)
20 to 26 min
Cure to a solid state
10 to 15 hrs
Cure to working strength
1 to 4 days
Min. recommended temp.
60°F (16°C)
WEST SYSTEM User Manual & Product Guide ||
Product Guide
Adhesive Fillers
Fairing Fillers
403 Microfibers
403 Microfibers, a fine fiber blend, is used as a
thickening additive that builds volume quickly and
blends easily to create a multipurpose adhesive,
especially for bonding wood. Epoxy thickened with
Microfibers has good gap-filling qualities while
retaining excellent wetting/penetrating capability.
Cures to an off-white color.
405 Filleting Blend
407 Low-Density
This strong, wood-toned filler is good for
use in glue joints and fillets on naturally-finished wood. It mixes easily with
epoxy and has good gap-filling properties. It cures to a dark brown color, and
can be used to modify the color of other
WEST SYSTEM fillers.
407 Low-Density Filler is a blended
microballoon-based filler used to make
fairing putties that are easy to sand or
carve. Reasonably strong on a strengthto-weight basis. Cures to a dark red/
brown color.
404 High-Density
406 Colloidal Silica
410 Microlight®
404 High-Density Filler is a thickening
additive developed for maximum physical
properties in hardware bonding where
high-cyclic loads are anticipated. It can
also be used for filleting and gap-filling
where maximum strength is necessary.
Cures to an off-white color.
406 Colloidal Silica is a thickening additive used to
control the viscosity of the epoxy and prevent epoxy
runoff in vertical and overhead joints. 406 is a very
strong filler that creates a smooth mixture, ideal for
general bonding and filleting. It is also our most versatile
filler. Often used in combination with other fillers, it can
be used to improve the strength, abrasion resistance, and
consistency of fairing compounds, resulting in a tougher,
smoother surface. Cures to an off-white color.
410 Microlight is the ideal low-density filler
for creating a light, easily-worked fairing
compound especially suited for fairing large
areas. Microlight mixes with greater ease
than 407 Low-Density Filler or microballoons and is approximately 30% easier to
sand. It feathers to a fine edge and is also
more economical for large fairing jobs. Not
recommended under dark paint or other
surfaces subject to high temperatures.
Cures to a light tan color.
|| WEST SYSTEM User Manual & Product Guide
Product Guide
Fillers are used to thicken the basic resin/hardener mixture for specific
applications. Each filler possesses a unique set of physical characteristics,
but they can be generally categorized as either Adhesive (high-density) or
Fairing (low-density).
Filler Selection Guide
Highest Density
Highest Strength
Uses—Use description—desired characteristics
(Resin/Hardener mixture thickened with a Filler)
Lowest Density
Easiest Sanding
Colloidal Silica
Filleting Blend
General Bonding—Join parts with epoxy thickened to create a
structural gap filler—strength/gap filling
Bonding with Fillets—Increase joint bonding area and create a
structural brace between parts—smoothness/strength
Laminating—Bond layers of wood strips, veneers, planks, sheets
and cores—gap filling/strength
Bonding Hardware—Increased fastener interface and hardware
load capability—maximum strength
Fairing—Fill low areas and voids with an easily sanded surface
filler/fairing compound—sandability/gap filling
Filler suitability for various uses: =excellent, =very good, =good, =fair, (no stars)=not recommended.
Filler Buying Guide
Quantity of Mixed Epoxy Required for:
Package Size
peanut butter
6.0 oz
3.8 qt
2.5 qt
1.0 qt
20.0 oz
3.2 gal
2.0 gal
.9 gal
20.0 lb
48.0 gal
32.0 gal
15.3 gal
15.2 oz
1.2 qt
.9 qt
.7 qt
43.0 oz
3.6 qt
2.8 qt
2.0 qt
30.0 lb
9.4 gal
7.4 gal
5.3 gal
11.0 oz
.8 qt
.6 qt
.5 qt
1.7 oz
1.3 qt
.9 qt
.5 qt
5.5 oz
1.1 gal
3.0 qt
1.7 qt
10.0 lb
27.0 gal
16.0 gal
6.0 gal
4.0 oz
.5 qt
.4 qt
.3 qt
12.0 oz
1.7 qt
1.3 qt
1.0 qt
14.0 lb
6.0 gal
4.8 gal
3.7 gal
2.0 oz
1.2 qt
.9 qt
.7 qt
5.0 oz
3.0 qt
2.4 qt
1.8 qt
4.0 lb
8.9 gal
7.2 gal
5.6 gal
Adhesive fillers are suitable for most
bonding situations especially high-density
materials like hardwoods and metals. Adhesive filler mixtures cure to a strong, hard-tosand plastic useful in structural applications
like bonding, filleting and hardware bonding.
Fairing filler mixtures cure to light, easily
sandable material that is generally used
for cosmetic or surface applications like
shaping, filling or fairing. Seal all faired
surfaces with epoxy before painting.
General use filler selection may be
based on the handling characteristics you
prefer. Fillers may also be blended to create
mixtures with intermediate characteristics.
Estimates based on 72°F. More filler/less epoxy may be required at higher temperatures.
WEST SYSTEM User Manual & Product Guide ||
Product Guide
Additives are blended with mixed epoxy to alter the
physical properties of epoxy when used as a coating.
Additives can be used to alter the color, abrasion
resistance or moisture resistance of cured epoxy.
420 Aluminum Powder
423 Graphite Powder
420 Aluminum Powder will
increase the hardness and
abrasion resistance of the coated
surface and improve its moisture
resistance. 420 provides limited
protection from ultraviolet light in
areas that will not be protected
with other coatings and can be
used as a base for subsequent
painting. Cures to a metallic
gray color.
423 Graphite Powder is a fine
black powder that can be mixed
with WEST SYSTEM epoxy to
produce a low-friction exterior
coating with increased scuff
resistance and durability. Epoxy/
graphite is commonly used as
a low-load, low-speed bearing
surface, and as a coating on
rudders and centerboards, or
on the bottoms of racing craft
that are dry sailed. It does not
provide antifouling qualities. The
epoxy/graphite mixture cures to a
black color.
Add to mixed resin/hardener at
the rate of 5%–10% by volume
or 1½ tablespoons per 8 fl oz of
epoxy (10 strokes each of resin
and hardener from 300 Mini
Pumps). 36 oz. of 420 will modify
up to five gallons of mixed epoxy.
420-36 36 oz.
Add to mixed resin/hardener at
the rate of 10% by volume or 1½
tablespoons per 8 fl. oz. of epoxy.
12 oz. can of 423 will approximately one gallon of epoxy.
423 12 oz.
|| WEST SYSTEM User Manual & Product Guide
422 Barrier Coat
A proprietary blend designed to
improve cured epoxy’s moisture-exclusion effectiveness.
422 is used as a barrier coating
additive to help prevent gelcoat
blistering in polyester fiberglass
boat hulls. 422 also increases
the epoxy’s abrasion resistance.
Cures to a light gray color.
Add to mixed resin/hardener at the
rate of 15 to 20% by volume or 3
tablespoons per 8 fl oz. of epoxy.
16 oz. can of 422 will modify
approximately half a gallon of epoxy.
422-16 16 oz.
Color Pigments
WEST SYSTEM pigments are
epoxy-based liquid colorants
used to tint the epoxy mixture
to provide an even color base
for the final finish system. The
colored surfaces also tend to
highlight flaws and imperfections.
Cured, pigmented epoxy surfaces
are not a final finish surface, but
require an additional paint or UV filter
coating for ultraviolet protection. Add
to the mixed resin/hardener at a rate
of approximately one teaspoon of
pigment to 8 fl oz of epoxy. More
pigment will increase opaqueness
and mixture viscosity. One 4 fl. oz.
bottle will tint approximately 1½
gal of epoxy.
501 White Pigment 4 fl. oz.
502 Black Pigment 4 fl. oz.
503 Gray Pigment 4 fl. oz.
Product Guide
Metering Pumps
Metering Pumps
300 Mini Pump Set
300 Mini Pumps are designed for convenient
and accurate metering of Group Size A, B
and C WEST SYSTEM 105 Resin-based epoxy.
The 300 Mini Pump Set contains one resin
pump and two hardener pumps. Pumps
mount directly on the resin and hardener
containers and eliminate the mess involved
with measuring by weight or volume.
300 Mini Pumps are calibrated to deliver the
proper working ratio with one full pump stroke
of resin for each one full pump stroke
of hardener. 105/205-206 pumps deliver
approximately 0.8 fl oz of resin/hardener with
one full stroke of each pump. 105/207-209
pumps deliver approximately 0.9 fl oz of resin/
hardener with one full stroke of each pump.
Made of durable polypropylene, the pumps
give years of dependable service. Read and
follow the priming, ratio verification and operating instructions that come with the pumps.
As packaged, the pumps are ready to install
on the Group Size B containers. A package of
extension tubes for Group Size A containers is
included with the set. Group Size C extension
tubes are included in the 105-C Resin and in
the 207-SC or 209-SC packages.
Large Capacity Pumps
306-23 Metering Pump
Similar to 306-25 Metering Pump described
above. For metering 105 Resin and 207
Special Clear or 209 Extra Slow (3:1 ratio)
Hardeners. Can be converted to 5:1 ratio.
306-25 Metering Pump
For metering 105 Resin and 205 or 206 (5:1
ratio) Hardeners. The 306-25 Pump will reduce
mixing time and waste on large projects. A
Metering Scale
carrying handle allows you to move the pump
320 Small-Batch Epoxy Scale
where the work is. Reservoirs hold one gallon
For batches smaller than one Mini Pump
of resin, one quart of hardener. Dispenses
stroke, the 320 scale accurately measures the approximately 0.5 fl oz of resin/hardener per
correct ratio of resin and hardener from 4.4 fl. pump stroke (about 1 qt per minute).
oz. down to just a few drops of mixed product.
The scale can also be used to confirm the
306-Kit Rebuild Kit
accuracy of your WEST SYSTEM dispensing
For all 306 pumps. Includes seals, balls,
pumps and to consistently add pigments or
gaskets, springs, high-rise tubes with ferrules
other additives. The scale comes in a conveand new resin and hardener reservoirs with lids.
nient kit for small projects. The kit includes
dispensing bottles, 3¼ oz. and 1 oz. plastic
mixing cups, mixing sticks, and pipe cleaners.
303 Positive Displacement Pump
This positive displacement metering pump
dispenses three parts resin and one part hardener (3:1) by volume. It consists of two separate parallel pump systems, one for the resin
and one for the hardener. The two systems
are operated simultaneously by a single lever.
The pump delivers 2.3 fl. oz. of resin and
hardener per full stroke of the dispensing
lever. The reservoirs hold two gallons of resin
and one gallon of hardener.
305 Positive Displacement Pump
Similar to 303 Positive Displacement Pump
described above, the 305 pump is designed
to accurately dispense WEST SYSTEM resins
and hardeners at 5:1 by volume.
WEST SYSTEM User Manual & Product Guide ||
Product Guide
Reinforcing Materials
Woven E-Glass
Glass Fabrics
737 Biaxial Fabric
Woven E-glass fabrics are ideal for building
composite laminates and repairing fiberglass
structures. May also be used to provide an
abrasion-resistant covering for wooden structures. When wet-out, the 4 and 6 oz fabrics
become transparent, allowing a clear, natural
wood finish. Perfect for stripper canoes. May
be painted or varnished.
17 oz non-woven E-glass fabric. Two
layers, ±45° fiber orientation. For
composites, repairs and reinforcing.
Achieves high fiber-to-resin ratio
with hand wet-out.
740-10 4 oz– 50" wide × 10 yd roll
740-20 4 oz– 50" wide × 20 yd roll
742-10 6 oz– 60" wide × 10 yd roll
742-20 6 oz– 60" wide × 20 yd roll
745-10 10 oz– 60" wide × 10 yd roll
745-20 10 oz– 60" wide × 20 yd roll
745-30 10 oz– 30" × 30" sheet
Unidirectional Carbon
Fabric Weight
Single Layer Thickness*
4 oz
6 oz
11 oz
11 oz
9 oz
10 oz
17 oz
23.8 oz
737-20 50" wide × 20 yd roll.
738 Biaxial Fabric with Mat
17 oz non-woven E-glass fabric.
Two layers, ±45° fiber orientation.
The same as 737 fabric with a .75
oz/sq ft mat backing. Approximately
23.8 oz/sq yd total fabric weight.
738-20 50" wide × 20 yd roll.
*Average of multiple layers applied by hand lay-up
Biaxial Glass
Unidirectional Carbon Tapes
713 Unidirectional Glass Tape
Glass Tape
Unidirectional 11.1 oz carbon fiber reinforcing
tapes are used for selective reinforcement to
improve tensile strength and stiffness in one
direction while adding minimum thickness and
weight. Fiber bundles are held in place by a
polyester fill thread for easy handling and wet
out. 144,000 fibers per inch of tape width.
Unidirectional 11.1 oz E-glass fiber reinforcing
tape is used to add strength in one direction,
but with less stiffness than carbon fiber. Easy
to handle and wet out.
Versatile WEST SYSTEM 9 oz woven E-glass
fabric tapes, with bound edges, are ideal
for reinforcing chines, hull/deck corners and
similar structural applications. When bonded
with WEST SYSTEM Epoxy, they provide additional tensile strength to resist hairline crack
development and abrasion.
702-12 1½" wide × 12' roll.
702-50 1½" wide × 50' roll.
703-12 3" wide × 12' roll.
703-50 3" wide × 50' roll.
713-50 3" wide × 50' roll.
727 Biaxial Tape
17 oz non-woven E-glass fabric. Two layers at
a ±45° fiber orientation are held together by
a light stitching. Flat, non-crimped fibers yield
reduced print-through and higher stiffness
than woven fabrics. Ideal for repairs, tabbing
and reinforcing.
727-10 4" wide × 10' roll.
727-20 4" wide × 20 yd roll.
To determine the number of
fabric layers required to achieve
a specific laminate thickness,
divide the thickness desired by
the single layer thickness of the
tape or fabric you intend to use.
|| WEST SYSTEM User Manual & Product Guide
729-10 2" wide × 10' roll
729 2" wide × 50 yd roll
731 3" wide × 50 yd roll
732-10 4" wide × 10' roll
732 4" wide × 50 yd roll
733 6" wide × 50 yd roll
Product Guide
Application Tools
800 Roller Covers
802 Roller Pan
These thin polyurethane foam covers are the
only roller covers recommended for epoxy
application. The thin foam allows you to control
film thickness, avoid drips and runs and get a
smoother coating. The 7" covers can be cut for
smaller jobs, narrow strips and tight areas. Cut
segments make ideal tipping brushes.
Heavy duty, flexible plastic roller pan allows
you to “pop out” epoxy after it has cured so
the pan can be re-used. Eliminates the need
for liners. 1 ea.
800-2 2 ea.
803 Glue Brushes
Handy, disposable, ½" × 6" glue application
brushes with a metal handle. These brushes
are useful in a wide variety of small bonding
and coating applications.
803-12 12 ea.
803-144 144 ea.
Cut into segments for tipping off
freshly applied coats of epoxy
Cut covers into narrower widths
to coat smaller areas
801-HD Roller Frame
3" caged roller frame holds 7" full-width covers
and covers cut to narrower widths. 1 ea.
Epoxy will not bond to many plastic tools
or mixing pots because their glossy
surface does not provide enough texture,
or tooth, for epoxy to key into. When
cured, flex the tool to loosen epoxy. Thick
films pop off easier than thin films. As a
tool gets scuffed and scratched from use,
it will become more difficult to pop the
cured epoxy from the surface.
804 Reusable Mixing Sticks
A practical mixing, application, filleting, and
cleaning tool. Squared, beveled end reaches
mixing pot corners for thorough mixing and
blending in fillers and for cleaning up excess
epoxy. Use rounded end to shape 3/8" radius
fillets. Cured epoxy pops off easily, so they
can be reused many times. ¾"-wide × 5½".
804-8 8 ea.
804-60 60 ea.
805 or 806 Mixing Pots
Cured epoxy pops out of these heavy-duty,
reusable plastic mixing pots. Convenient batch
sizes for most projects. Pots are calibrated to
help mix larger batches.
805 16 oz pot, 1 ea.
806 32 oz pot, 1 ea.
807 Syringes
Reusable syringes that can be loaded with
epoxy mixture for injecting into tight spots.
Ideal for hardware bonding and small repairs.
Holds 12 cc (about 0.4 fl oz).
807-2 2 ea.
807-12 12 ea.
808 Flexible Plastic Spreader
Flexible, reusable 3½"× 6" double-edged
spreader for flow coating, fairing, filling and
applying fabrics.
808-2 2 ea.
808-12 12 ea.
809 Notched Spreader
Stiff 4" × 4" plastic spreader with 1/8", 3/16"
and ¼" notches on three sides for quickly
applying thickened epoxy at a constant rate
over large areas. Thin straight edge is ideal for
applying layers of reinforcing fabrics.
809 1 ea.
810 Fillable Caulking Tubes
For use with a standard caulking gun. Great for
injecting large amounts of epoxy, laying a lengthy
bead of epoxy or making fillets. Can be refilled
several times, before epoxy begins to cure.
Tubes can be refilled again after cured epoxy is
popped out. Holds approximately 10 fl oz.
810-2 2 ea.
810-24 24 ea.
WEST SYSTEM User Manual & Product Guide ||
Product Guide
Specialty Items
Vacuum Bagging Materials
879 Release Fabric
Release Fabric is a tough, finely woven nylon
fabric treated with a release agent. It is used
to separate the breather fabric and vacuum
bag from the laminate in vacuum bagging
operations. Excess epoxy bleeds through and
is peeled from the cured laminate along with
the Release Fabric. It’s also used in hand
lay-up applications to allow more squeegee
pressure and protect the lay-up from contamination and blush. Peels easily and leaves a
smooth textured surface, ready for bonding,
sanding or finishing. Not recommended for
post-cure temperatures over 120°F (49°C).
879-2 60" wide × 2 yd roll
879-10 60" wide × 10 yd roll
879-18 60" wide × 9" sheet
881 Breather Fabric
Breather Fabric is a lightweight, polyester blanket
that provides excellent air passage within the
vacuum envelope while it absorbs excess epoxy.
881-10 45" wide × 10 yd roll
Vacuum Bagging is a clamping system used
for laminating a wide range of fabrics, core
materials and veneers. It uses atmospheric
pressure to deliver firm, even clamping pressure
over the entire surface area of a composite part
or repair, regardless of the material or materials
being laminated. By laminating over simple
molds, composites can be molded into an
endless variety of functional shapes.
882 Vacuum Bag Film
Clear, heat-stabilized, modified nylon resin
film. Can be used at temperatures up to
350°F (176°C) for typical composite cure
cycle times. A tough, stretchable film for
high vacuum pressures.
882-20 60" wide × 20 yd roll
883 Vacuum Bag Sealant
Mastic tape sealant for airtight seals
between vacuum bags and molds. Easy to
work around difficult angles, patching small
leaks in the vacuum system.
½" wide × 25' roll
885-5 Vacuum Gauge
0–30 Hg (mercury) vacuum gauge.
885-6 Venturi Vacuum Generator
Includes silencer. Generator develops over
20 inches Hg (mercury) of vacuum (10 psi)
at .4 SCFM (standard cubic feet per minute)
and is designed to run off of conventional
shop air compressors delivering at least 65 psi
at 3.5 SCFM continuously.
885-34 Vacuum Cups and Tubing
Includes 3 vacuum cups and 20' of ¼" I.D.
vacuum tubing.
885 Vacuum Bagging Kit
A complete starter kit for room temperature
repairs and small laminating projects up to 13
square feet. Some item specifications may vary.
Kit includes:
• Venturi Vacuum Generator with Silencer
• 3 Vacuum Cups, 20' of ¼" I.D. Vacuum Tubing
• 0–30Hg Vacuum Gauge
• 2 Junction “T” barbs
• 15 sq. ft. Release Fabric
• 15 sq. ft. Breather Fabric
• 15 sq. ft. Vacuum Bag Film
• 25' Vacuum Bag Sealant
• Complete, illustrated instructions
Special Tools
875 Scarffer®
A unique tool designed by boatbuilders for
cutting accurate scarf joints in plywood up to ³/8"
thick. Attaches easily to most circular saws and
is easily removed. Saw must have a base plate
extension (outside of the blade) ½" or wider.
1 ea (saw not included).
|| WEST SYSTEM User Manual & Product Guide
Product Guide
Skin Protection
Our personal protective clothing is made out of a
microporous film laminate material which provides a
superior combination of strength, barrier protection
and breathability.
832 Disposable Gloves
836 Coverall
Lightweight, seamless neoprene gloves are
more chemically resistant than latex gloves.
They provide excellent protection while retaining
good finger sensitivity and dexterity and they
are more puncture resistant than conventional
disposable gloves. Large size fits most.
These suits are inexpensive enough to be
disposable, yet durable enough to be reused again
and again. For maximum personal protection, use
coveralls with gloves to prevent accidental contact
with uncured epoxy. Elastic wrists and ankles
help prevent sleeves and pant legs from riding up.
Coveralls available in large,
extra-large and XXL.
832-4 4 pr.
832-50 50 pr.
834 Lab Coat
For upper body protection, use the lab coats
with gloves to prevent accidental skin and
clothing contact with uncured epoxy.
834-L 1 ea.
834-XL 1 ea.
835 Apron
For torso protection, use the aprons with gloves
to prevent accidental contact with uncured
epoxy. For added protection, use with sleeves.
835 1 ea.
836-L 1 ea.
836-XL 1 ea.
836-XXL 1 ea.
838 Sleeves
If you need to cover only
your arms, try these
convenient sleeves.
18" sleeves with elastic
top and cuff. Use with
coverall and gloves for
extra protection.
838-2 2 pr.
It is much easier and safer to
keep epoxy off your skin than
it is to clean it off. Gloves,
coveralls, aprons, lab coats and
sleeves help you work clean.
Working Cleanly
In addition to gloves, coveralls,
aprons, lab coats and sleeves,
there are a two other common,
yet essential, items you can use
to help contain epoxy and work
more cleanly.
Always keep a roll of paper
towels within reach before
mixing a batch of epoxy. We
recommend using paper
towels to clean spills and wipe
up excess epoxy. To remove
contamination from bonding
surfaces, we recommend
plain white (non-printed)
towels as the ink may be
a contaminant that can
affect bonding.
It is also a good practice to use
plastic sheeting (4 or 6 mil) to
protect floors and work surfaces
from epoxy spills and mask off
areas of your project you want
to protect.
Epoxy won’t bond to plastic
sheeting and will peel off when
cured. Use small pieces of plastic
under clamps to avoid inadvertent
bonding. Clear plastic packaging tape
also works well to protect clamps,
tools and other surfaces you
don’t want epoxy to stick to.
WEST SYSTEM User Manual & Product Guide ||
Product Guide
For more about West System products or technical information for a
building or repair project, Gougeon Brothers offers a range of detailed
publications that can help get you started. Our print publications are
available as free downloadable PDFs at
002-898 WEST SYSTEM Epoxy
How-To DVD
002 The Gougeon Brothers on
Boat Construction
002-550 Fiberglass Boat Repair &
A compilation of three instructional videos
demonstrating basic handling and advanced
epoxy repair techniques. Basic Application
Techniques—A guide to the optimum use of
WEST SYSTEM Epoxy products, including epoxy
safety and procedures for coating, bonding
and fairing. Fiberglass Repair with WEST
SYSTEM Epoxy—making structural repairs on
fiberglass boats, including repairs to cored
and non-cored hulls and how to apply gelcoat
over epoxy repairs. Gelcoat Blister Repair with
WEST SYSTEM Epoxy—A guide for analyzing
the causes of blister formation, repairing and
preventing gelcoat blisters on fiberglass boats.
Interactive menus allow for easy navigation
through these subjects. DVD—59 minutes.
Decades of experience building with wood and
epoxy are compiled in this classic on wood/
epoxy boat building. Extensive chapters on
lofting, safety, tools and construction methods
are described with the aid of hundreds of
detailed illustrations and photographs. This 5th
edition includes about 20% new and updated
material and a revised layout for easier
navigation. Used as a textbook in boat building
schools. Over 100,000 copies in print. Hardcover—406 pages.
This is a complete, illustrated guide to a
variety of fiberglass repair problems, including
detailed instructions on repairing cracks and
holes, delamination, rot and keel damage. It
also covers fairing keels, hardware bonding,
final fairing and finishing, installing teak
veneers and gelcoat blister diagnosis, prevention and repair. Softcover—122 pages.
|| WEST SYSTEM User Manual & Product Guide
002-970 Wooden Boat Restoration & Repair
This manual shows you how to do professional
level repairs and renovations that dramatically
extend the life of your wooden boat. Dry rot
repairs, structural frame repairs, and plank
repairs using modern products and techniques
are among the many solutions covered in this
fully illustrated manual. Softcover—80 pages.
Product Guide
(USA and Canada only)
EPOXYWORKS is a FREE semiannual magazine published by Gougeon Brothers, Inc. It
discusses building, restoring and repairing
with epoxy. It offers helpful tips, the latest
techniques, projects you can build, readers’
projects, and news from the Gougeon
research and test labs.
Subscribe to the print edition of EPOXYWORKS by calling Gougeon Brothers at
866-937-8797, or by visiting
or to fill out the online form.
Subscriptions do not expire.
You can also view current or back issues of
EPOXYWORKS online at and
follow us on Facebook at Digital-only subscriptions are available
by emailing [email protected]
Our website is a great resource for product
information, technical information such as
SDS, how-to videos, customer projects, the
latest updates and dealer information. Search
our extensive database for articles on boat
repair and construction, techniques and
materials, home and architecture, building and
restoring vehicles of every kind and the arts.
Safety Data Sheets
Safety Data Sheets (SDS) for specific WEST
SYSTEM products are available at westsystem.
com, through WEST SYSTEM distributors or by
contacting Gougeon Brothers, Inc. For additional
information about the use or suitability of WEST
SYSTEM products contact the Gougeon Technical
Staff at 866-937-8797.
WEST SYSTEM User Manual & Product Guide ||
User Manual
|| WEST SYSTEM User Manual & Product Guide
User Manual
Epoxy Handling
This section explains the fundamentals of epoxy safety, curing and the
steps for proper dispensing, mixing and adding fillers to assure that every
batch cures to a reliable high-strength solid.
Epoxy Safety
1. Avoid contact with resin, hardeners, mixed epoxy and sanding dust from epoxy that is
not fully cured. Wear protective gloves and clothing whenever you handle WEST SYSTEM
Epoxies. If you do get resin, hardener or mixed epoxy on your skin, remove it as soon as
possible. Resin is not water soluble—use a waterless skin cleanser to remove resin or
mixed epoxy from your skin. Hardener is water soluble—wash with soap and warm water
to remove hardener or sanding dust from your skin. Always wash thoroughly with soap
and warm water after using epoxy. Never use solvents to remove epoxy from your skin.
Stop using the product if you develop an allergic type of reaction. Resume work only after
the symptoms disappear, usually after several days. When you resume work, improve
your safety precautions to prevent exposure to epoxy, its vapors, and sanding dust. If
problems persist, discontinue use and consult a physician.
1. Protect your eyes from contact with resin, hardeners, mixed epoxy, and sanding dust by
wearing appropriate eye protection. If contact occurs, immediately flush the eyes with
water under low pressure for 15 minutes. Seek medical attention or advice.
2. Avoid breathing concentrated vapors and sanding dust. WEST SYSTEM Epoxies have
low volatile organic content (VOC), but vapors can build up in unventilated spaces. Use
adequate ventilation to avoid breathing vapors, fumes and sanding dust, particularly when
working in confined spaces, such as boat interiors. When ventilation cannot be made
adequate to keep exposures below safe levels, use a NIOSH approved respirator with an
organic vapor cartridge, organic vapor cartridge + P100 particulate filter or a multi-contaminant cartridge. Consult with your respiratory and cartridge supplier to ensure the
proper selection based on chemical ingredients and specific workplace conditions.
WEST SYSTEM User Manual & Product Guide ||
User Manual
Provide ventilation and wear a dust mask when sanding epoxy, especially uncured
epoxy. Breathing dust from epoxy that is not fully cured increases your risk of sensitization. Although epoxy cures quickly to a sandable solid, it may take over two weeks
at room temperature, or post-curing, to cure completely.
3. Avoid ingestion. Wash thoroughly after handling epoxy, especially before eating or
smoking. If epoxy is swallowed, rinse mouth with water—DO NOT induce vomiting.
Because hardeners are corrosive, they can cause additional harm if vomited. Call a
physician immediately. Refer to First Aid procedures on the Safety Data Sheet.
CHILDREN. For additional safety information or data, refer to the Safety Data Sheets
or write to: EPOXY SAFETY, WEST SYSTEM, P.O. Box 908, Bay City, MI 48707 USA
Caution! Large pots of curing
epoxy can get hot enough to ignite
surrounding combustible materials
and give off hazardous fumes.
Place pots of mixed epoxy in a safe
and ventilated area, away from
workers and combustible materials.
Dispose of the solid mass only if
cure is complete and the mass has
cooled. Follow federal, state or local
disposal regulations.
Epoxies are safe when handled properly. To use WEST SYSTEM Epoxies safely, you must
understand their hazards and take precautions to avoid them.
The primary hazard associated with epoxy involves skin contact. WEST SYSTEM Resins
may cause moderate skin irritation. WEST SYSTEM Hardeners are corrosive and may
cause severe skin irritation. Resins and hardeners are also sensitizers and may cause an
allergic reaction similar to poison ivy. Susceptibility and the severity of a reaction varies
with the individual. Although most people are not sensitive to WEST SYSTEM Resins and
Hardeners, the risk of becoming sensitized increases with repeated contact. For those
who become sensitized, the severity of the reaction may increase with each contact.
These hazards also apply to the sanding dust from epoxy that has not fully cured. These
hazards decrease as resin/hardener mixtures reach full cure. Refer to product labels or
Safety Data Sheets (SDS) for specific product warnings and safety information.
Contain large spills with sand, clay or other inert absorbent material. Use a squeegee to
contain small spills and collect as much material as possible. Follow up with absorbent towels.
DO NOT use sawdust or other fine cellulose materials to absorb hardeners.
DO NOT dispose of hardener in trash containing sawdust or other cellulose materials—
spontaneous combustion can occur.
Clean resin or mixed epoxy residue with lacquer thinner, acetone or alcohol. Follow all
safety warnings on solvent containers. Clean hardener residue with warm soapy water.
Clean 207 Hardener residue with lacquer thinner, acetone or alcohol.
Dispose of resin, hardener and empty containers safely. Puncture a corner of the can
and drain residue into the appropriate new container of resin or hardener. DO NOT
dispose of resin or hardener in a liquid state. Waste resin and hardener can be mixed
and cured (in small quantities) to a non-hazardous inert solid.
Removing uncured or non-curing epoxy. Uncured epoxy is removed as you would
spilled resin. Scrape as much material as you can from the surface using a stiff metal or
plastic scraper—warm the epoxy to lower its viscosity. Clean the residue with lacquer
thinner, acetone, or alcohol. (Follow safety warnings on solvents, and provide adequate
ventilation.) Allow solvents to dry before re-coating.
Removing fiberglass cloth applied with epoxy. Use a heat gun to heat and soften the
epoxy. Start in a small area a near a corner or edge. Apply heat until you can slip a putty
|| WEST SYSTEM User Manual & Product Guide
User Manual
knife or chisel under the cloth (about 250°F). Grab the edge with a pair of pliers and
slowly pull up on the cloth while heating just ahead of the separation. On large areas,
use a utility knife to score the glass and remove in narrower strips. Resulting surface
texture may be coated or remaining epoxy may be removed as follows. Provide ventilation or wear a respirator when heating epoxy.
Removing cured epoxy coating. Use a heat gun to soften the epoxy (about 250°F).
Heat a small area and use a paint or cabinet scraper to remove the bulk of the coating.
Sand the surface to remove the remaining material. Provide ventilation or wear a respirator when heating epoxy.
Epoxy Chemistry
Epoxy’s Cure Stages
Mixing 105 Epoxy Resin® with a hardener begins a chemical reaction that transforms the
combined liquid ingredients to a solid. This period of transformation is the cure time. As
it cures, epoxy passes from the liquid state, through a gel state, before it reaches a solid
state (Figure 1).
CAUTION! Heating epoxy that has
not gelled will lower its viscosity,
allowing the epoxy to run or sag
more easily on vertical surfaces. In
addition, heating epoxy applied to a
porous substrate (soft wood or low
density core material) may cause
the substrate to “out-gas” and form
bubbles or pinholes in the epoxy
coating. To avoid out-gassing, wait
until the epoxy coating has gelled
before warming it. Never heat mixed
epoxy in a liquid state over 120°F
(49°C). Regardless of what steps
are taken to control the cure time,
thorough planning of the application
and assembly will allow you to make
maximum use of epoxy’s open time
and cure time.
Figure 1 As it cures, mixed epoxy
passes from a liquid state,
through a gel state, to a solid
Cure time is shorter when
the epoxy is warmer.
Cure time is longer when
the epoxy is cooler.
Liquid—Open Time
Open time (also working time or wet lay-up time) is the portion of the cure time, after mixing,
that the resin/hardener mixture remains a liquid and is workable and suitable for application. All
assembly and clamping should take place during the open time to ensure a dependable bond.
Gel—Initial Cure Phase
The mixture passes into an initial cure phase (also called the green stage) when it begins to
gel, or “kick-off.” The epoxy is no longer workable and will progress from a tacky, gel consistency to the firmness of hard rubber, which you will be able to dent with your thumbnail.
The mixture will become tack free about midway through the initial cure phase. While
it is still tacky (about like masking tape), a new application of epoxy will still chemically
bond with it, so you may still bond to or recoat the surface without special preparation.
However, this ability diminishes as the mixture approaches the final cure phase.
Solid—Final Cure Phase
The epoxy mixture has cured to a solid state and can be dry sanded. You will no longer be
able to dent it with your thumbnail. At this point the epoxy has reached most of its ultimate
strength, so clamps can be removed. A new application of epoxy will no longer chemically
bond to it, so the surface of the epoxy must be properly prepared and sanded before
re-coating to achieve a good mechanical, secondary bond. See Surface Preparation.
You can improve epoxy’s thermal performance and reduce
the potential for fabric
“print-through” by applying modest heat to
the epoxy after it has
cured to a solid state.
Contact our technical
staff for more information about post
The mixture will continue to cure for the next several days to two weeks at room
temperature, becoming an inert plastic solid.
WEST SYSTEM User Manual & Product Guide ||
User Manual
Controlling Cure Time
Open time and overall cure time govern much of the activity of building and repairing
with epoxy. Open time dictates the time available for mixing, application, smoothing,
shaping, assembly and clamping. Cure time dictates how long you must wait before
removing clamps, or before you can sand or go on to the next step in the project. Two
factors determine an epoxy mixture’s open time and overall cure time—hardener cure
speed and epoxy temperature.
1. Hardener Cure Speed
Each hardener has an ideal temperature cure range. At any given temperature, each
resin/hardener combination will go through the same cure stages, but at different
rates. Select the hardener that gives you adequate working time for the job you are
doing at the temperature and conditions you are working under. The Hardener Selection Guide and container labels describe hardener pot lives and cure times.
WARNING! Curing epoxy generates
heat. Do not fill voids or cast layers
of epoxy thicker than ½"—thinner if
enclosed by foam or other insulating
material. Several inches of mixed
epoxy in a confined mass (such as
a mixing cup) will generate enough
heat to melt a plastic cup, burn your
skin or ignite combustible materials
if left to stand for its full pot life.
For this reason do not use foam or
glass mixing containers or pour into
confined spaces. If a pot of mixed
epoxy begins to exotherm (heat
up), quickly move it outdoors. Avoid
breathing the fumes. Do not dispose
of the mixture until the reaction is
complete and has cooled.
Pot life is a term used to compare the cure speeds of different hardeners. It is the
amount of time a specific mass of mixed resin and hardener remains a liquid at a
specific temperature (a 100g-mass mixture in a standard container, at 72°F). Because
pot life is a measure of the cure speed of a specific contained mass (volume) of epoxy
rather than a thin film, a hardener’s pot life is much shorter than its open time.
2. Epoxy Temperature
The warmer the temperature of curing epoxy, the faster it cures (Figure 1, page 23).
The temperature of curing epoxy is determined by the ambient temperature plus the
exothermic heat generated by its cure.
Ambient temperature is the temperature of the air or material in contact with the
epoxy. Air temperature is most often the ambient temperature unless the epoxy is
applied to a surface with a different temperature. Generally, epoxy cures faster when
the air temperature is warmer.
Exothermic heat is produced by the chemical reaction that cures epoxy. The amount
of heat produced depends on the thickness or exposed surface area of mixed epoxy.
In a thicker mass, more heat is retained, causing a faster reaction and more heat. The
mixing container’s shape and the mixed quantity have a great effect on this exothermic
reaction. A contained mass of curing epoxy (8 fl oz or more) in a plastic mixing cup can
quickly generate enough heat to melt the cup and burn your skin. However, if the same
quantity is spread into a thin layer, exothermic heat is dissipated, and the epoxy’s cure
time is determined by the ambient temperature. The thinner the layer of curing epoxy,
the less it is affected by exothermic heat, and the slower it cures.
Adapting to Warm and Cool Temperatures
In warm conditions, gain open time by using a slower hardener. Mix smaller batches that
can be used up quickly, or pour the epoxy mixture into a container with greater surface area
(a roller pan, for example), thereby allowing exothermic heat to dissipate and extending open
time. The sooner the mixture is transferred or applied (after thorough mixing), the more of
the mixture’s useful open time will be available for coating, lay-up or assembly.
In cool conditions use a faster hardener, or use supplemental heat to raise the epoxy
temperature above the hardener’s minimum recommended application temperature. Use
a hot air gun, heat lamp or other heat source to warm the resin and hardener before
mixing or after the epoxy is applied. At room temperature, supplemental heat is useful
when a quicker cure is desired. NOTE! Unvented kerosene or propane heaters can inhibit
the cure of epoxy and contaminate epoxy surfaces with unburned hydrocarbons.
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Dispensing and Mixing 105 Resin and
Careful measuring of epoxy resin and hardener and thorough mixing are essential for
a proper cure. Whether the resin/hardener mixture is applied as a coating or modified
with fillers or additives, observing the following procedures will assure a controlled and
thorough chemical transition to a high-strength epoxy solid.
Dispense the correct proportions of resin and hardener into a clean plastic, metal or
wax-free paper container (Figure 2). Don’t use glass or foam containers because of the
potential danger from exothermic heat buildup.
Figure 2 Dispense the proper propor-
tions of resin and hardener.
With Mini Pumps—Pump one full pump
stroke of resin for each one full pump
stroke of hardener.
DO NOT attempt to adjust the epoxy cure time by altering the mix ratio. An accurate ratio
is essential for a proper cure and full development of physical properties.
Dispensing With Mini Pumps
Most problems related to curing of the epoxy can be traced to the wrong ratio of resin and
hardener. To simplify dispensing and reduce the possibility of errors, we recommend using
calibrated WEST SYSTEM Mini Pumps to meter the correct working ratio of resin to hardener.
Pump one full pump stroke of resin for each one full pump stroke of hardener.
Depress each pump head fully and allow the head to come completely back to the top
before beginning the next stroke. Partial strokes will give the wrong ratio. Read the
pump instructions before using pumps.
Before you use the first mixture on a project, verify the correct ratio according to the
instructions that come with the pumps. Recheck the ratio anytime you experience problems with curing.
Dispensing Without Mini Pumps—Weight/Volume Measure
To measure 105 Resin and 205 or 206 Hardener by weight or volume, combine 5 parts
resin with 1 part hardener. To measure 105 Resin and 207 or 209 Hardener by volume,
combine 3 parts resin with 1 part hardener. To measure 207 or 209 Hardener by weight,
combine 3.5 parts resin with 1 part hardener. (The weight measurement for these ratios
is slightly different from the volume ratio due to hardener density.)
First Time Users
If this is the first time you have used WEST SYSTEM Epoxy, begin with a small test batch
to get the feel for the mixing and curing process, before applying the mixture to your
project. This will demonstrate the hardener’s open time for the temperature you are
working in and assure you that the resin/hardener ratio is metered properly. Mix small
batches until you are confident of the mixture’s handling characteristics.
Stir the two ingredients together thoroughly—at least 1 minute—longer in cooler
temperatures (Figure 3). To assure thorough mixing, scrape the sides and bottom of the
pot as you mix. Use the flat end of the mixing stick to reach the inside corner of the pot.
If you are using a power mixer, occasionally scrape the sides and corners of the mixing
pot while mixing. If you are going to be using the mixture for coating, quickly pour it into
a roller pan to extend the open time.
Scrape Corners
Figure 3 Stir resin and hardener together
thoroughly—at least 1 minute, longer in
cooler temperatures.
If you have any questions about selecting
or using WEST SYSTEM
products that are not
answered in this manual, contact our technical staff. Call 866937-8797 toll free or
where you can fill out
a form and receive an
emailed response to
your question.
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Figure 4 Epoxy can
be thickened to
the ideal consistency needed for a
particular job. The
procedures in this
manual refer to four
common consistencies: syrup, catsup,
mayonnaise and
peanut butter.
Unthickened (neat)
Slightly Thickened
Moderately Thickened
Maximum Thickness
Peanut Butter
Drips off vertical surfaces.
Sags down vertical
Clings to vertical
surfaces, peaks fall over.
Clings to vertical
surfaces, peaks stand up.
Coating, “wetting-out”
before bonding, applying
fiberglass, carbon fiber
and other fabrics.
Laminating/bonding flat
panels with large surface
areas, injecting with a
General bonding, filleting,
hardware bonding.
Gap filling, filleting,
fairing, bonding uneven
Adding Fillers and Additives
Figure 5 Stir in small handfuls of filler
until the desired consistency is
Throughout this and other WEST SYSTEM manuals, we refer to epoxy or resin/hardener
mixture, meaning mixed resin and hardener without fillers added; and thickened mixture
or thickened epoxy, meaning mixed resin and hardener with fillers added. Fillers are
used to thicken epoxy for specific applications such as bonding or fairing.
After selecting an appropriate filler for your job (see Filler Selection Guide, page 11), use
it to thicken the epoxy mixture to the desired consistency. The thickness of a mixture
required for a particular job is controlled by the amount of filler added. There is no strict
formula or measuring involved—use your eye to judge what consistency will work best.
Figure 4 gives you a general guide to the differences between unthickened (neat) epoxy
and the three consistencies referred to in this manual.
Always Add Fillers in a Two-Step Process:
1. Mix the desired quantity of resin and hardener thoroughly before adding fillers. Begin
with a small batch—allow room for the filler.
2. Blend in small amounts of the appropriate filler until the desired consistency is
reached (Figure 5).
For maximum strength, add only enough filler to completely bridge gaps between
surfaces without sagging or running out of the joint or gap. A small amount should
squeeze out of joints when clamped. For thick mixtures, don’t fill the mixing cup more
than 1/3 full of epoxy before adding filler. When making fairing compounds, stir in as
much 407 or 410 as you can blend in smoothly—for easy sanding, the thicker the
better. Be sure all of the filler is thoroughly blended before the mixture is applied.
Spread the mixture into a thinner layer, either around the inside of the mixing cup or onto
a flat non-porous surface or palette to extend its working life.
Thinning Epoxy
There are epoxy-based products specifically designed to penetrate and reinforce rotted
wood. Those products, basically an epoxy thinned with solvents, do a good job of penetrating wood. But the solvents compromise the strength and moisture barrier properties
of the epoxy. WEST SYSTEM Epoxy can be thinned with solvents for greater penetration,
but this results in similar compromises in strength and moisture resistance. Acetone and
lacquer thinner have been used to thin WEST SYSTEM Epoxy and duplicate these pene26
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trating epoxies with about the same effectiveness. If you choose to thin the epoxy, keep
in mind that the strength, especially compressive strength, and moisture protection of
the epoxy are lost in proportion to the amount of solvent added.
There is a better solution to get good penetration without losing strength or moisture
resistance. We recommend moderate heating (up to 120°F) of the project area with a
heat gun or heat lamp before applying epoxy. On contact with the warmed substrate, the
epoxy will thin out, penetrating cavities and pores, and will be drawn even deeper into
pores as the substrate cools. Although the working life of the epoxy will be considerably
shortened, slower hardeners (206, 207, 209) will have a longer working life and should
penetrate more than 205 Hardener before they begin to gel. When the epoxy cures it will
retain all of its strength and effectiveness as a moisture barrier, which we feel more than
offsets any advantages gained by adding solvents to the epoxy.
Additives are used to give epoxy additional physical properties when used as a coating.
Although additives are blended with mixed epoxy in the same two-step process as
fillers, they are not designed to thicken the epoxy. Refer to the Additive descriptions.
Follow the mixing instructions on the individual additive containers.
Coloring Epoxy
West System pigments are available to color epoxy black, white or gray. Powdered
pigments (tempera paint, colored tile grout, aniline dyes) and universal tinting pigment
can be added to the epoxy mixture to tint it any color. Acrylic paste pigments (available
from marine chandleries) can also be used to tint the mixture, as long as they are specified for use with polyester or epoxy resin. 423 Graphite Powder will also color the epoxy
black or impart darker shades to colors.
Generally, coloring agents can be added to the mixed epoxy up to 5% by volume with
minimal effect on the cured epoxy’s strength. Always make test samples to check for
desired color and opaqueness and for proper cure. None of these coloring additives
provide UV resistance to the cured epoxy, so limit their use to areas not exposed to
sunlight unless additional UV protection is applied.
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Basic Techniques
The following basic techniques are common to most repair or
building projects, regardless of the type of structure or material you
are working with.
Surface Preparation
Figure 6 Clean the surface. Use a
solvent, if necessary, to remove all
Whether you are bonding, fairing or applying fabrics, the success of the application
depends not only on the strength of the epoxy, but also on how well the epoxy adheres
to the surface to which it is being applied. Unless you are bonding to partially cured
epoxy, the strength of the bond relies on the epoxy’s ability to mechanically “key” into
the surface. That is why the following three steps of surface preparation are a critical
part of any secondary bonding operation.
For good adhesion, bonding surfaces should be:
1. Clean—Bonding surfaces must be free of any contaminants such as grease, oil,
wax or mold release. Clean contaminated surfaces with lacquer thinner, acetone or
other appropriate solvent (Figure 6). Wipe the surface with paper towels before the
solvent dries. Clean surfaces before sanding to avoid sanding the contaminant into
the surface. Follow all safety precautions when working with solvents.
Figure 7 Dry the surface. Allow wet
surfaces to dry thoroughly or use heat
or a fan to speed drying.
2. Dry—All bonding surfaces must be as dry as possible for good adhesion. If necessary, accelerate drying by warming the bonding surface with a hot air gun, hair dryer
or heat lamp (Figure 7). Use fans to move the air in confined or enclosed spaces.
Watch for condensation when working outdoors or whenever the temperature of the
work environment changes.
3. Sanded—Sand smooth non-porous surfaces—thoroughly abrade the surface
(Figure 8). 80-grit aluminum oxide paper will provide a good texture for the epoxy to
“key” into. Be sure the surface to be bonded is solid. Remove any flaking, chalking,
blistering, or old coating before sanding. Remove all dust after sanding.
Figure 8 Sand non-porous surfaces.
Provide a texture for epoxy to key into.
Special Preparation for Various Materials
Cured Epoxy—Amine blush may appear as a wax-like film on cured epoxy surfaces,
except for epoxy 207 Special Clear Hardener. It is a byproduct of the curing process and
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may be more noticeable in cool, moist conditions. Amine blush can clog sandpaper and
inhibit subsequent bonding, but it is water soluble and can easily be removed. It’s a good
idea to assume it has formed on any cured epoxy surface.
To remove the blush, wash the surface with clean water (not solvent) and an abrasive
pad, such as Scotch-brite™ 7447 General Purpose Hand Pads. Dry the surface with paper
towels to remove the dissolved blush before it dries on the surface. Sand any remaining
glossy areas with 80-grit sandpaper. Wet-sanding will also remove the amine blush. If a
release fabric is applied over the surface of fresh epoxy, amine blush will be removed when
the release fabric is peeled from the cured epoxy and no additional sanding is required.
Epoxy surfaces that are still tacky may be bonded to or coated with epoxy without
washing or sanding. Before applying coatings other than epoxy (paints, bottom paints,
varnishes, gelcoats, etc.), allow epoxy surfaces to cure fully, then wash and sand.
Hardwoods—Sand with 80-grit paper.
Teak/Oily Woods—Wipe with acetone 15 minutes before coating, allowing the solvent
to evaporate before coating. Use G/flex epoxy for bonding.
Porous Woods—No special preparation needed. If surface is burnished, possibly by dull
planer or saw blades, sand with 80-grit paper to open pores. Remove dust.
Steel, Lead—Remove contamination, sand or grind to bright metal, coat with epoxy
then (wet) sand freshly applied epoxy into surface. Re-coat or bond after first coat gels.
Aluminum—Remove contamination, sand to a bright finish and then wet sand. Follow
kit directions. Use G/flex epoxy, especially on flexible pieces.
Fiberglass (Polyester)—Clean contamination with a silicone and wax remover such as
DuPont Prep-Sol™ 3919S. Sand with 80-grit paper to a dull finish.
Plastic—Clean plastics, except for polycarbonate, with isopropyl alcohol to remove
contamination. Sand all plastics including polycarbonate with 80-grit sandpaper to
provide texture for good adhesion. Flame treat (Pass the flame of a propane torch across
the surface quickly—about 12 inches per second) ABS and PVC for additional benefit.
HDPE (high-density polyethylene) and LDPE (low-density polyethylene) must be flame
treated for good adhesion. Use G/flex epoxy for plastics.
Bonding (Gluing)
This section describes two methods of structural bonding. Two-step bonding is the preferred
method for most situations because it promotes maximum epoxy penetration into the
bonding surface and prevents epoxy-starved joints. Single-step bonding can be used when
joints have minimal loads and excess absorption into porous surfaces is not a problem. In
both cases, epoxy bonds best when it is worked into the surface with a roller or brush.
Before mixing epoxy, check all parts to be bonded for proper fit and surface preparation
(see Surface Preparation), gather all the clamps and tools necessary for the operation,
and cover any areas that need protection from spills.
Primary/Secondary Bonding
Primary bonding relies on the chemical bonding of adhesive layers such as the wet
lay-up of fiberglass laminate in a mold. All the layers of adhesive cure together into
a single fused layer. Epoxy applied over partially cured epoxy will chemically bond
with it and is considered a primary bond. The ability to chemically bond diminishes
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as the previous layer of epoxy cures. You must then prepare the cured surface for a
secondary bond.
Secondary bonding relies on mechanical, rather than chemical, bonding of an adhesive
to a material or cured epoxy surface. The adhesive must “key” into pores or scratches
in the surface—a microscopic version of a dovetail joint. Proper surface preparation
provides a texture that will help bond the cured epoxy to the surface. Except for bonding
to uncured or partially cured epoxy surfaces, all epoxy bonds are secondary bonds.
Figure 9 Apply resin/hardener mixture to
the bonding surfaces.
Any method of clamping is suitable as long as there is no movement between the parts
being joined. Common methods include spring clamps, “C” clamps and bar clamps,
rubber bands, packaging tape, applying weights, and vacuum bagging. If necessary,
cover clamp pads with tape, or use polyethylene sheeting or release fabric under the
clamps so they don’t inadvertently bond to the surface. Staples, nails or drywall screws
are often used where conventional clamps will not work. In a corrosive environment,
any fasteners left in should be a non-corroding alloy such as bronze. In some cases the
thickened epoxy or gravity will hold parts in position without clamps. Avoid excessive
clamping pressure.
Two-Step Bonding
Figure 10 Apply thickened epoxy to one
of the bonding surfaces.
1. Wet-out bonding surfaces—Apply an unthickened resin/hardener mixture to the
surfaces to be joined (Figure 9). Wet out small or tight areas with a disposable brush.
Wet out larger areas with a foam roller or by spreading the resin/hardener mixture
evenly over the surface with a plastic spreader. You may proceed with step two
immediately or any time before the wet-out coat becomes tack free.
2. Apply thickened epoxy to one bonding surface. Modify the resin/hardener mixture
by stirring in the appropriate filler until it becomes thick enough to bridge any gaps
between the mating surfaces and to prevent “epoxy-starved” joints. Apply enough of
the mixture to one of the surfaces so that a small amount will squeeze out when the
surfaces are joined together with a force equivalent to a firm hand grip (Figure 10).
Figure 11 Clamp components in place
before the epoxy gels.
Thickened epoxy can be applied immediately over the wet-out surface or any time
before the wet-out is no longer tacky. For most small bonding operations, add the
filler to the resin/hardener mixture remaining in the batch that was used for the
wet-out. Mix enough resin/hardener for both steps. Add the filler quickly after the
surface is wet out and allow for a shorter working life of the mixture.
3. Clamp components. Attach clamps as necessary to hold the components in place.
Use just enough clamping pressure to squeeze a small amount of the epoxy mixture
from the joint, indicating that the epoxy is making good contact with both mating
surfaces (Figure 11). Avoid using too much clamping pressure, which can squeeze all
of the epoxy mixture out of the joint.
Figure 12 Remove or shape excess epoxy
that squeezes out of the joint.
4. Remove or shape excess adhesive that squeezes out of the joint as soon as the joint
is secured with clamps. An 804 mixing stick is an ideal tool for removing the excess
(Figure 12). Allow to cure thoroughly before removing clamps.
Single-Step Bonding
Single-step bonding is applying the thickened epoxy directly to both bonding surfaces
without first wetting out the surfaces with neat resin/hardener. We recommend that you
thicken the epoxy no more than is necessary to bridge gaps in the joint (the thinner the
mixture, the more it can penetrate the surface) and that you do not use this method for
highly-loaded joints, especially when bonding end grain or other porous surfaces.
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The term “laminating” refers to the process of bonding numbers of relatively thin layers,
like plywood, veneers, fabrics or core material to create a composite. A composite
may be any number of layers of the same material or combinations of different materials. Methods of epoxy application and clamping will differ depending on what you
are laminating.
Because of large surface areas and limitations of wet lay-up time, roller application is
the most common method for applying epoxy. A faster method for large surfaces is to
simply pour the resin/hardener mixture onto the middle of the panel and spread the
mixture evenly over the surface with a plastic spreader. Apply thickened mixtures with
an 809 Notched Spreader.
Using staples or screws is the most common method of clamping when you laminate a
solid material to a solid substrate. An even distribution of weights will work when you
are laminating a solid material to a base that will not hold staples or screws, such as a
foam or honeycomb core material.
Vacuum bagging is a specialized clamping method for laminating a wide range of materials. Through the use of a vacuum pump and vacuum bag film, the atmosphere is used
to apply perfectly even clamping pressure over all areas of a panel regardless of the size,
shape or number of layers.
Bonding with Fillets
Pre-coating porous
surfaces with neat
(unthickened) epoxy before applying
a thickened epoxy
adhesive or fairing
compound improves
adhesion. Neat epoxy
penetrates and “keys”
into surface pores and
end grain better than
thicker epoxy.
A fillet (fil’it) is a cove-shaped application of thickened epoxy that bridges an inside
corner joint. It is excellent for bonding parts because it increases the surface area of the
bond and serves as a structural brace. All joints that will be covered with fiberglass cloth
will require a fillet to support the cloth at the inside corner of the joint.
Joint strength is the ability of a joint to adequately transfer a load from one part to
another—depends on the combined effects of three factors.
GLUE STRENGTH—Careful metering and thorough mixing will assure the epoxy
mixture cures to full strength.
ADHESION—For the best adhesion and load transfer, the joint’s bonding surfaces
must be properly prepared.
JOINT AREA—The bonding area of the joint must be adequate for the load on the
joint and materials being joined. Increased overlap, scarf joints, fillets and reinforcing
fibers can be used to increase joint bonding area.
The procedure for bonding with fillets is the same as normal bonding except that instead
of removing the squeezed-out thickened epoxy after the components are clamped in
position, you shape it into a fillet. For larger fillets, add thickened mixture to the joint as
soon as the bonding operation is complete, before the bonding mixture becomes tack
free, or any time after the final cure and sanding of exposed epoxy in the fillet area.
1. Bond parts as described in Bonding.
2. Shape and smooth the squeezed-out thick epoxy into a fillet by drawing a rounded
filleting tool (804 Mixing Stick) along the joint, dragging excess material ahead of
the tool and leaving a smooth cove-shaped fillet bordered on each side by a clean
margin. Some excess filleting material will remain outside of the margin (Figure 13).
Use the excess material to refill any voids. Smooth the fillet until you are satisfied
with its appearance. A mixing stick will leave a fillet with about a 3/8" radius. For
Figure 13 Shape and smooth the fillet
with a rounded filleting tool.
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larger fillets, an 808 Plastic Spreader, cut to shape or bent to the desired radius,
works well.
Apply additional thickened epoxy to fill voids or make larger fillets. Apply the mixture
along the joint line with the rounded mixing stick, using enough mixture to create
the desired size of fillet. For longer or multiple fillets, empty caulking gun cartridges
or disposable cake decorating bags can be used. Cut the plastic tip to lay a bead of
thickened epoxy large enough for the desired fillet size. Heavy duty, sealable food
storage bags with one corner cut off may also be used.
Figure 14 Clean up the excess epoxy
outside of the fillet margin.
3. Clean up the remaining excess material outside of the margin by using a mixing stick
or a putty knife (Figure 14). Fiberglass cloth or tape may be applied over the fillet
area before the fillet has cured (or after the fillet is cured and sanded).
4. Sand smooth with 80-grit sandpaper after the fillet has fully cured. Wipe the surface
clean of any dust and apply several coats of resin/hardener over the entire fillet area
before final finishing.
Bonding Fasteners and Hardware
Epoxy Annulus
Figure 15 Wet out a standard pilot hole
and install the fastener.
Installing screws and other threaded fasteners with WEST SYSTEM Epoxy dramatically
improves load carrying capacity by spreading the fastener’s load into a greater area of
the substrate. There are several methods or levels of hardware bonding depending on
the loads on the hardware.
Basic Fastener Bonding
Figure 16 Drill oversized holes to
increase the exposed substrate area
and the amount of epoxy around the
For improved pullout strength and waterproof connections, the easiest fastener bonding
method is to simply wet out stripped fastener holes and new pilot holes before installing
the screws. Epoxy penetrates the fiber around the hole, effectively increasing the
fastener diameter. Epoxy also provides a stronger interface with the fastener threads
than wood fiber and keeps out water.
1. Wet out a standard-size pilot hole. Work the mixture well into the hole with a pipe
cleaner or syringe (Figure 15). Thicken a second coat of epoxy as necessary for
stripped or oversized holes.
2. Insert the fastener in the hole and allow the epoxy to cure.
Advanced Fastener Bonding
For greater strength and stability, drill oversized holes to increase the exposed substrate
area and the amount of epoxy around the fastener.
1. Drill oversized holes 2/3 – 3/4 the depth of the fastener. The hole diameter is ¼" larger
than the fastener diameter (Figure 16-a).
2. Drill a normal sized pilot hole at the bottom of the oversized hole to the full length
of the fastener. The normal sized pilot hole serves to hold or clamp the hardware
in position until the epoxy cures. If the fastener/hardware can be clamped by other
means, the oversized hole can be extended to the end of the fastener.
3. Wet out the holes and the fastener with epoxy. Allow the epoxy to thoroughly soak
into the exposed substrate.
4. Fill the hole with thickened epoxy/adhesive filler. Use 404 High-Density (preferred) or
406 Colloidal Silica.
5. Install the fasteners with just enough force to hold the hardware in place. Allow the
epoxy to cure thoroughly before applying load to the hardware (Figure 16-b).
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Bonding Hardware
Bonding hardware goes a step beyond bonding the fasteners only. By bonding the
hardware base directly to the surface you further increase hardware load capacity and
provide a solid bearing surface for the hardware. It also seals the substrate underneath,
and is a stronger, longer lasting attachment than bonding the fasteners only. It is especially useful to mount hardware on curved, uneven or un-level surfaces.
1. Prepare the mounting surface and the hardware base for good adhesion (see Surface
2. Wet out the oversized hole with epoxy. Allow the epoxy to soak into the exposed
substrate (as with faster bonding).
Figure 17 Coat the hardware bottom and
the fastener threads with thickened
3. Coat the bottom contact surface of the hardware with unthickened epoxy. Wire brush
or sand the wet epoxy into the surface with 50-grit sandpaper.
4. Inject a non-sagging epoxy/404 or 406 mixture into the hole. Use enough mixture
so there are no voids in the hole after inserting the fastener. Coat the bottom of the
hardware and the fastener threads with thickened epoxy (Figure 17).
5. Place the hardware in position. Insert and tighten fasteners until a small amount of
the mixture squeezes out of the joint (Figure 18).
Backing Plate
Figure 18 Tighten fasteners until a small
amount of epoxy squeezes from the
6. Remove excess epoxy or shape into a fillet. Allow the epoxy to cure at least 24 hours
before applying load to the hardware. Allow more time in cool weather.
Casting a Base
Use the thickened epoxy to cast a base under the hardware when mounting hardware to
a curved or uneven surface, or mounting hardware at an angle to the surface.
1. Prepare the fasteners, holes, substrate and base as described above.
2. Bond small blocks to the substrate to support the base at the desired height and
position (e.g., winch base, Figure 19-a).
3. Apply enough thickened epoxy to cover the blocks. If the gap between the base and
the surface is over ½", fill the gap in two separate layers to avoid exotherm.
4. Place the hardware in position, resting on the blocks (Figure 19-b) and install
the fasteners.
5. Smooth the excess epoxy into the desired fillet shape around the base (Figure 19-c).
Allow the epoxy to cure fully before loading. Protect exposed epoxy from UV.
Bonding Studs
Bond threaded rods or studs into the substrate (instead of bolts or screws) and attach
the hardware with nuts. This variation is appropriate for many engine, motor or machine
installations. Coat the base with wax/mold release to make the hardware removable.
Although the hardware is not “bonded” to the substrate, the epoxy will still provide a
bearing surface that perfectly matches and supports the base of the hardware.
Figure 19 Support the base in position
with blocking. Fill the void with thickened epoxy.
Slightly Above Surface
1. Prepare the stud/threaded rod by waxing the upper end (above the surface) and
cleaning the lower end (below the surface). Place a nut on the stud, positioned with
the top of the nut slightly above the surface.
2. Fill the hole 2/3 full with epoxy. Allow to penetrate and refill as necessary.
3. Wet out the lower end of the stud and push it into the epoxy filled hole. Top off the
hole or clean away excess as necessary. Allow the epoxy to cure thoroughly before
attaching hardware and tightening the nut (Figure 20).
Figure 20 Bond threaded rods or studs
into the substrate as an alternative for
easily removable hardware.
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User Manual
Removing Fasteners
If you know that you will want to remove the fastener, you can coat the threads with wax
or mold release (contaminating the surface enough to prevent a good bond).
Remove a permanently bonded fastener by applying heat to the head of the fastener with
a soldering iron or propane torch. Use a heat shield to protect the surrounding area. Heat
will travel down the fastener, softening the epoxy in contact with it. At about 250°F the
epoxy should soften enough to allow the fastener to be backed out. Allow more time for
heat to travel down longer or larger diameter fasteners.
Figure 21 Wet out porous surfaces
before applying fairing compound.
Fairing refers to the filling of low areas and the shaping and smoothing of a surface to
blend with the surrounding areas and appear “fair” to the eye and touch. After major
structural assembly has been completed, final fairing can be easily accomplished with
WEST SYSTEM Epoxy and low-density fillers.
1. Prepare the surface as you would for bonding (see Surface Preparation). Sand smooth
any bumps or ridges on the surface and remove all dust from the area to be faired.
2. Wet out porous surfaces with unthickened epoxy (Figure 21).
Figure 22 Apply fairing compound to fill
all voids and smooth to shape.
3. Mix resin/hardener and 407 Low-Density or 410 Microlight® filler to a peanut butter
consistency. The thicker the mixture, the easier it will be to sand when cured.
4. Trowel on the thickened epoxy mixture with a plastic spreader, working it into all
voids and depressions. Smooth the mixture to the desired shape, leaving the mixture
slightly higher than the surrounding area (Figure 22). Remove any excess thickened
epoxy before it cures. If the voids you are filling are over ½" deep, apply the mixture
in several applications or use 206 Slow Hardener® or 209 Extra Slow Hardener™,
depending on ambient temperature.
Figure 23 Sand cured fairing compound
to desired contour.
Note: On vertical and overhead surfaces, allow the wet-out coat to gel before
applying fairing compound. The fairing compound may sag or slide off the fresh
wet-out coat. Apply the fairing compound while the wet-out is still tacky.
5. Allow the final thickened epoxy application to cure thoroughly.
6. Sand the fairing material to blend with the surrounding contour (Figure 23). Begin
with 50-grit sandpaper if you have a lot of fairing material to remove. Use 80-grit
paper on the appropriate sanding block when you are close to the final contour.
CAUTION! Don’t forget your dust mask. Remove the sanding dust and fill any
remaining voids following the same procedure.
7. Apply several coats of resin/hardener to the area with a disposable brush or roller
after you are satisfied with the fairness. Allow the final coat to cure thoroughly before
final sanding and finishing. Note: 410 Microlight filler can be affected by the solvents
in most paints. Surfaces faired with 410 filler must be sealed with epoxy before
applying any solvented paints.
Applying Woven Cloth and Tape
Fiberglass cloth is applied to surfaces to provide reinforcement and/or abrasion resistance. It is usually applied after fairing and shaping are completed, and before the final
coating operation. It is also applied in multiple layers and in combination with other
materials to build composite parts.
Fiberglass cloth may be applied to surfaces by either of two methods. The “dry” method
refers to applying the cloth over a dry surface. The “wet” method refers to applying the
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User Manual
cloth to an epoxy-coated surface often after the wet-out coat becomes tacky, which helps
it cling to vertical or overhead surfaces. Since this method makes it more difficult to position the cloth, the dry method is the preferred method especially with thinner cloth.
Dry Method
1. Prepare the surface as you would for bonding (see Surface Preparation).
2. Position the cloth over the surface and cut it several inches larger on all sides. If the
surface area you are covering is larger than the cloth size, allow multiple pieces to
overlap by approximately two inches. On sloped or vertical surfaces, hold the cloth in
place with masking or duct tape, or with staples.
Figure 24 Spread the epoxy over the
cloth surface with a plastic spreader.
3. Mix a small quantity of epoxy (three or four pumps each of resin and hardener).
4. Pour a small pool of resin/hardener near the center of the cloth.
5. Spread the epoxy over the cloth surface with a plastic spreader, working the epoxy
gently from the pool into the dry areas (Figure 24). Use a foam roller or brush to wet
out fabric on vertical surfaces. Properly wet out fabric is transparent. White areas
indicate dry fabric. If you are applying the cloth over a porous surface, be sure to
leave enough epoxy to be absorbed by both the cloth and the surface below it. Try
to limit the amount of squeegeeing you do. The more you “work” the wet surface,
the more minute air bubbles are placed in suspension in the epoxy. This is especially
important if you plan to use a clear finish. You may use a roller or brush to apply
epoxy to horizontal as well as vertical surfaces.
Smooth wrinkles and position the cloth as you work your way to the edges. Check for
dry areas (especially over porous surfaces) and re-wet them with epoxy as necessary
before proceeding to the next step. If you have to cut a pleat or notch in the cloth to
lay it flat on a compound curve or corner, make the cut with a pair of sharp scissors
and overlap the edges for now.
6. Squeegee away excess epoxy before the first batch begins to gel (Figure 25). Slowly
drag the spreader over the fabric at a low (almost flat) angle, using even-pressured,
overlapping strokes. Use enough pressure to remove excess epoxy that would allow the
cloth to float off the surface, but not enough pressure to create dry spots. Excess epoxy
appears as a shiny area, while a properly wet-out surface appears evenly transparent,
with a smooth, cloth texture. Later coats of epoxy will fill the weave of the cloth.
7. Trim the excess (Figure 26) and overlapped cloth after the epoxy has reached its
initial cure. The cloth will cut easily with a sharp utility knife. Trim overlapped cloth, if
desired, as follows:
Figure 25 Squeegee away excess epoxy
before it begins to gel.
Figure 26 Trim excess cloth after the
epoxy gels.
Figure 27 Trim overlapped cloth after the
epoxy gels.
a) Place a metal straightedge on top of and midway between the two overlapped edges.
b) Cut through both layers of cloth with a sharp utility knife (Figure 27), being very
careful not to cut too deeply.
c) Remove the topmost trimming and then lift the opposite cut edge to remove the
overlapped trimming (Figure 28). d) Re-wet the underside of the raised edge with
epoxy and smooth into place.
Figure 28 Remove the topmost trimming,
lift the opposite cut edge to remove
the overlapped trimming.
The result should be a near perfect butt joint, eliminating double cloth thickness. A
lapped joint is stronger than a butt joint, so if appearance is not important, you may
want to leave the overlap and fair in the unevenness after coating.
8. Coat the surface to fill the weave before the wet-out becomes tack free (Figure 29).
Follow the procedures for final coating in the next section. It will take two or three
coats to completely fill the weave of the cloth and provide a thick enough coating to
allow for a final sanding that will not affect the cloth.
Figure 29 Coat the surface to fill the weave
before the wet-out becomes tack free.
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A variation of this method is to apply the fabric after a wet out coat has cured thoroughly
and the surface has been prepared for bonding. This method assures a thorough wet out of
the substrate and fabric, and the fabric can still be positioned easily while it is being wet out.
Wet Method
An alternative is to apply the fabric or tape to a surface coated with wet epoxy. As
mentioned, this is not the preferred method, especially with large pieces of cloth,
because of the difficulty removing wrinkles or adjusting the position of the cloth as it
is being wet out. However, you may come across situations, such as applying fabric on
vertical or overhead surfaces, when this method may be useful or necessary.
1. Prepare the surface for bonding (see Surface Preparation). Pre-fit and trim the cloth to
size. Roll the cloth neatly so that it may be conveniently rolled back into position later.
2. Roll a heavy coat of epoxy on the surface.
3. Unroll the glass cloth over the wet epoxy and position it. Surface tension will hold
most cloth in position. If you are applying the cloth vertically or overhead, you may
want to thicken the epoxy slightly with 406 filler, then wait until it becomes sticky.
Work out wrinkles by lifting the edge of the cloth and smoothing from the center with
your gloved hand or a plastic spreader.
4. Apply a second coat of epoxy with a foam roller. Apply enough epoxy to thoroughly
wet out the cloth.
5. Remove the excess epoxy with a plastic spreader, using long overlapping strokes.
The cloth should appear consistently transparent with a smooth cloth texture.
6. Follow steps 7 and 8 under the Dry method to finish the procedure.
Any remaining irregularities or transitions between cloth and substrate can be faired
by using an epoxy/filler fairing compound if the surface is to be painted. Any additional fairing done after the final coating should receive several additional coats over
the faired area.
Barrier Coating
The object of barrier coating is to build up an epoxy coating that provides an effective
moisture barrier and a smooth base for final finishing.
Apply a minimum of two coats of WEST SYSTEM Epoxy for an effective moisture barrier—
three coats if sanding is to be done (recommended for most wooden boats). Moisture
protection will increase with additional coats, up to six coats or about a 20 mil thickness.
Six coats, with 422 Barrier Coat Additive™ in the final five coats, provides maximum
moisture protection (recommended for polyester fiberglass boats with gelcoat blisters).
Additives or pigments should not be added to the first coat. Mixing thinners with WEST
SYSTEM Epoxy is not recommended (see Thinning Epoxy).
WEST SYSTEM 800 Roller Covers, allow you greater control over film thickness, are less
likely to cause the epoxy to exotherm and leave less stipple than thicker roller covers.
Cut the covers into narrower widths to reach difficult areas or for long narrow surfaces
like stringers. A paint brush can be used for smaller areas, if the bristles are stiff enough
to spread the epoxy to an even film. If necessary, cut the bristles shorter. Foam brushes
are generally too flexible.
Epoxy applied with the 800 Roller Cover at room temperature (70°F), and tipped off as
described, results in a film 3–4 mils thick. A 6 or 7 mil film thickness (two coats—three
coats if sanded) provides an excellent moisture barrier for most exterior surfaces. A 9 or
10 mil film thickness is the minimum recommended for hull bottoms or other surfaces
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User Manual
that are continuously wet. Additional coats provide additional moisture protection up to
20 mils (five or six coats). Epoxy film thickness per coat will vary with temperature—
thinner in warm temperatures, thicker in cooler temperatures.
Six coats with the last five modified with 422 Barrier Coat Additive provide maximum
protection and are generally recommended only for polyester fiberglass hull bottoms
prone to gelcoat blistering.
Complete all fairing and cloth application before beginning the final coating. Allow the
temperature of porous surfaces to stabilize before coating. Otherwise, as the material
warms up, air within the porous substrate may expand and pass from the material
(out-gassing) through the coating and leave bubbles in the cured coating.
Figure 30 Roll lightly and randomly over a
small area. Spread the epoxy into a thin
even film.
1. Prepare the surface for bonding (see Surface Preparation).
2. Mix only as much resin/hardener as you can apply during the open time of the
mixture. Pour the mixture into a roller pan as soon as it is mixed thoroughly.
3. Load the roller with a moderate amount of the epoxy mixture. Roll the excess out on
the ramp part of the roller pan to get a uniform coating on the roller.
4. Roll lightly and randomly over an area approximately 2'×2' to transfer the epoxy
evenly over the area (Figure 30).
5. As the roller dries out, increase pressure enough to spread the epoxy into a thin even
film. Increase the coverage area if necessary to spread the film more thinly and evenly.
The thinner the film, the easier it is to keep it even and avoid runs or sags in each coat.
Figure 31 Tip off the coating by dragging
a foam roller brush lightly over the
fresh epoxy.
6. Finish the area with long, light, even strokes to reduce roller marks. Overlap the
previously coated area to blend both areas together.
7. Coat as many of these small working areas as you can with each batch. If a batch
begins to thicken before it can be applied, discard it and mix a fresh, smaller batch.
8. Tip off the coating by dragging a foam roller brush lightly over the fresh epoxy in long,
even, overlapping strokes after each batch is applied. Use enough pressure to smooth
the stipple, but not enough to remove any of the coating (Figure 31). Alternate the
direction in which each coat is tipped off, 1st coat vertical, 2nd coat horizontal, 3rd coat
vertical, etc. An 800 Roller Cover can be cut into segments to make a tipping brushes.
Apply second and subsequent coats of epoxy following the same procedures. Re-coat
when the previous coat is still tacky (about as tacky as masking tape). To avoid sanding
between coats, apply all of the coats when previous coats have cured to this tacky
stage. After the final coat has cured, wash and sand it to prepare for the final finish (see
Surface Preparation—Cured Epoxy.)
Final Surface Preparation
Proper finishing techniques will not only add beauty to your efforts, but will also protect
your work from ultraviolet light, which will break down epoxy over time. The most
common methods of finishing are painting or varnishing. These coating systems protect
the epoxy from ultraviolet light and require proper preparation of the surface before
application. Preparation for the final finish is just as important as it is for re-coating with
epoxy. The surface must first be clean, dry and sanded.
1. Allow the final epoxy coat to cure thoroughly.
2. Wash the surface with a Scotch-brite™ pad and water to remove amine blush. Dry
with paper towels.
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User Manual
3. Sand to a smooth finish (Figure 32). If there are runs or sags, begin sanding with
80-grit paper to remove the highest areas. Sand until the surface feels and looks fair.
Complete sanding with the appropriate grit for the type of coating to be applied—
check coating instructions. Paint adhesion relies on the mechanical grip of the
paint keying into the sanding scratches in the epoxy’s surface. If a high-build or
filling primer is to be applied, 80–100 grit is usually sufficient. 120–180 grit may be
adequate for primers and high-solids coatings. Finishing with 220–400 grit paper will
result in a high-gloss finish for most paints or varnishes. Grits finer than this may not
provide enough tooth for good adhesion. Wet sanding is preferred by many people
because it reduces sanding dust and it will allow you to skip Step 2. See coating
manufacturer's instructions for proper surface preparation.
Figure 32 Sand to a smooth finish.
4. After you are satisfied with the texture and fairness of the surface, rinse the surface
with fresh water (Figure 33). Rinse water should sheet evenly without beading or
fish-eyeing. If rinse water beads up (a sign of contamination), wipe the area with
solvent and dry with a paper towel, then wet sand again until beading is eliminated.
Proceed with your final coating after the surface has dried thoroughly. To reduce
the possibility of contamination, it is a good idea to begin coating within 24 hours of
the final sanding. See coating manufacturer's instructions for proper surface
preparation. A good trick used by professionals is to make a test panel to evaluate
the degree of surface preparation required and the compatibility of the finish system.
Figure 33 Rinse the surface with
fresh water after sanding.
Finish Coatings
Coating Function
A finish coating—paint or varnish—over an epoxy barrier coat protects the epoxy from
sunlight as well as decorating the surface. In doing so, the finish coating extends the life
of the epoxy moisture barrier, which in turn, provides a stable base that extends the life
of the finish coating. Together, the two form a protective system far more durable than
either coating by itself.
Protection from sunlight is a primary consideration in the selection of a finish coating. Long
term UV protection of the barrier coat depends on how well the finish coating itself resists
UV and keeps its pigments, or its shield of UV filters on the surface of the epoxy barrier
coat. A high gloss finish reflects a higher proportion of the light hitting the surface than a
dull surface. All other things being equal, a white (especially a glossy white) coating will
last the longest.
Coating Compatibility
Most types of coatings are compatible with epoxy. Thoroughly cured epoxy is an almost
completely inert hard plastic. Most paint solvents will not soften, swell or react with it.
One-part polyurethanes and polyester gelcoat can be affected by epoxy amines and if used
must be applied when the epoxy is thoroughly cured, generally after two weeks at room
temperature. A thorough cure can be achieved much quicker with elevated temperature
post curing. Post curing will also improve epoxy’s thermal properties and is recommended
if dark paint is to be applied over epoxy.
Finish Coating Types
Latex paints are largely compatible with epoxy, even partially cured epoxy, and they do an
adequate job of protecting the epoxy barrier from UV radiation. In many architectural applications, a latex paint may be the most suitable coating to use. Their durability is limited.
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Alkyd finishes—enamel, alkyd enamel, marine enamel, acrylic enamel, alkyd modified
epoxy, traditional varnish and spar varnish—offer ease of application, low cost, low
toxicity, and easy availability. Their disadvantages are low UV resistance and low abrasion resistance. Make a test panel to ensure compatibility.
One-part polyurethanes offer easy application, cleanup and better properties than
alkyds. They are also more expensive and some may be incompatible with amine
cure epoxy systems such as WEST SYSTEM Epoxy, although 207 Hardener may offer
better compatibility. Be sure epoxy has cured thoroughly. Make a test panel to
ensure compatibility.
Epoxy paints are available in one-part and two-part versions. Two-part epoxies offer
many characteristics similar to the higher performance polyurethanes. They are durable
and chemical resistant, but offer limited UV protection compared to the linear polyurethanes. Make a test panel to ensure compatibility.
Two-part linear polyurethane (LP) paints offer the most durable protection available. LPs are available as pigmented or clear coatings and offer excellent UV protection, gloss retention, abrasion resistance, plus compatibility with epoxy. However,
compared to other types of coatings, they are expensive, require more skill to apply
and present a greater health hazard, especially when sprayed. Make a test panel to
ensure compatibility.
Bottom paints are available in a variety of formulations. Most bottom paint systems
are compatible with epoxy and can be applied directly over a prepared epoxy barrier
coat. If you are unsure of compatibility or have curing or adhesion problems with a
specific bottom paint, use only a primer recommended for that bottom paint over the
barrier coat. Follow the recommendations given for preparation of fiberglass surfaces.
Other paints, including marine LP’s and primers, are not recommended for use below
the waterline.
Primers are usually not needed to help a paint film bond to epoxy, although interfacing
primers may be required with some specialized bottom paints and high-build primers
are useful for hiding scratches or flaws in the substrate. If the instructions on your paint
or varnish recommend a specially primed surface, follow the recommendations given
for fiberglass preparation. Self-etching primers do not work well on an epoxy coating
because of epoxy’s chemical resistance. Make a test panel to ensure compatibility.
Polyester gelcoat is a pigmented version of the resin used to build fiberglass boats and
other products. Gelcoat is sprayed into a mold before the glass fabric and resin are applied to
provide a smooth pre-finished surface when the part is removed from the mold. It is not often
used as a post-production finish coating, but it can be applied over epoxy and is useful in
some repair situations. Epoxy must be cured thoroughly. Refer to 002-550 Fiberglass Boat
Repair & Maintenance, for detailed information on patching gelcoat over an epoxy repair.
Follow all instructions from the coating systems manufacturer. It is a good idea to
make a test panel to evaluate the degree of surface preparation required, and the
compatibility and handling characteristics of the finish system.
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User Manual
Problem Solver
This guide is designed to help identify and prevent potential problems you may encounter using
WEST SYSTEM Epoxy. If the solutions described here do not resolve the problem, call the Gougeon
Brothers technical staff, 866-937-8797.
Off ratio—too much or too little
hardener will affect the cure
time and thoroughness of the
1. Remove epoxy. Do not apply additional material over non-curing epoxy. See Removing
epoxy, page 22.
2. Check correct number of pump strokes—use equal strokes of resin and hardener. DO
NOT add extra hardener for faster cure!
3. Check for correct pump (5:1 or 3:1 ratio).
4. Check pump metering ratio (see pump instructions). See Dispensing, page 25.
Low temperature—epoxy
mixtures cure slower at low
1. Allow extra curing time in cool weather.
2. Apply heat to maintain the chemical reaction and speed the cure. Raise the temperature
above the hardener’s minimum recommended cure temperature. (NOTE! Unvented kerosene or propane heaters can inhibit the cure of epoxy and contaminate epoxy surfaces.)
3. Use a faster hardener, designed to cure at lower temperatures. See Controlling Cure
Time, page 24.
Possible Causes
The epoxy mixture has not cured after the recommended cure time has passed.
Insufficient mixing.
1. Remove epoxy. Do not apply additional material over non-curing epoxy. See Removing
Epoxy, page 22.
2. Mix resin and hardener together thoroughly to avoid resin rich and hardener rich areas.
3. Add fillers or additives after resin and hardener have been thoroughly mixed. See Mixing,
page 25.
Incorrect products.
1. Remove epoxy. Do not apply additional material over non-curing epoxy. See Removing
epoxy, page 22.
2. Check for proper resin and hardener. Resin will not cure properly with other brands of
hardener or with polyester catalysts.
Insufficient cure.
See above.
Resin starved joint-epoxy has
wicked into porous surfaces
leaving a void at the joint.
Wet out bonding surfaces before applying thickened epoxy. Re-wet very porous surfaces
and end grain. See Two-step Bonding, page 30.
Contaminated bonding surface.
Possible Causes
Bond Failure
Clean and sand the surface following the procedure on page 28. Sand wood surfaces
after planing or joining.
Bonding area too small for the
load on the joint.
Increase bonding area by adding fillets, bonded fasteners or scarf joints.
Too much clamping pressure
squeezed epoxy out of the joint.
Use just enough clamping pressure to squeeze a small amount of epoxy from the joint.
See Clamping, page 30.
Moisture from condensation or
very humid conditions reacts
with components in uncured
Entrapped air from aggressive
roller application.
Possible Causes
Clear coating turned cloudy.
1. Apply moderate heat to partially cured coating to remove moisture and complete cure.
See out-gassing caution, page 23.
2. Use 207 Special Clear Hardener for clear coating applications and for bonding thin
veneers where epoxy may bleed through to the surface.
1. Apply coating at warmer temperature—epoxy is thinner at warmer temperatures.
2. Apply epoxy in thin coats.
3. Apply moderate heat to release trapped air and complete cure. See Caution, page 23.
Amine blush formation is a
typical result of the curing
Waxy film appears on surface of cured epoxy.
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1. Blush is water soluble. Remove with water. See Special preparation—Cured Epoxy, page 28.
2. Use 207 Special Clear Hardener. 207 Hardener is blush free.
User Manual
Epoxy applied too thickly.
Possible Causes
Runs or sags in coating.
Coating curing too slowly.
1. Use 800 Roller Covers and roll the coating out into a thinner film. A thin film will flow
out much smoother than a thicker film after it is tipped off with the foam roller brush.
2. Warm the epoxy to thin it or apply the coating at a warmer temperature. See Barrier
Coating, page 36.
1. Apply the coating at a warmer temperature.
2. Warm the resin and hardener before mixing to speed the cure in cool weather.
3. Switch to a faster hardener if possible. See Controlling Cure Time, page 24.
Fairing material not thick
Fairing Compound (epoxy/407 or 410 mixture) sags and is difficult to sand.
Add more filler to the mixture until it reaches a “peanut butter” consistency—the more
filler added, the stiffer and easier it will be to sand.
Fresh epoxy wet-out won’t support weight of fairing.
Thick fairing compound (epoxy/407 or 410 mixture) sags.
Allow the wet-out coat to gel before applying the fairing material to vertical surfaces. See
Fairing, page 34.
Allow the final epoxy coat to cure thoroughly. Allow several days if necessary for slow
hardeners at cooler temperatures. Apply moderate heat to complete the cure if necessary.
See Controlling Cure Time, page 24.
Epoxy not completely cured.
Coating incompatible with
Possible Causes
Paint, varnish or gelcoat will not set up over epoxy.
Epoxy surface not thoroughly
1. Use a different type of paint. Some paints and varnishes may be incompatible with
some hardeners. If unsure, test for compatibility on a coated piece of scrap material.
2. Use 207 Hardener. It is compatible with most paints and varnishes.
Remove the amine blush and sand the surface thoroughly before applying paints or varnishes. See Final Surface Preparation, page 37.
Batch too large, or left in mixing pot too long.
Temperature too warm for the
Possible Causes
Epoxy became very hot and cured too quickly.
Application too thick.
1. Mix smaller batches.
2. Transfer the mixture to a container with more surface area,such as a paint roller tray, immediately after mixing. See Controlling Cure Time, page 24, Dispensing and Mixing, page 25.
Use 206 Slow or 209 Extra Slow Hardener in very warm weather.
Apply thick areas of fill in several thin layers.
Air trapped in the material
escapes through coating
(out-gassing) as the material’s
temperature is rising.
Bubbles formed in coating over porous material (bare wood or foam).
1. Coat the wood as its temperature is dropping—after warming the wood with heaters or
during the later part of the day.
2. Apply a thinner coat, allowing air to escape easier.
3. Tip off the coating with a roller cover brush to break bubbles. See Caution, page 23.
Surface tension causes epoxy
film to pull away from pinhole
before it gels.
After applying epoxy with an 800 Roller Cover, force epoxy into pinholes with a stiff plastic or metal spreader held at a low or nearly flat angle. Re-coat and tip off coating after all
pinholes are filled.
Pinholes appear in epoxy coating over abraded fiberglass or epoxy.
1. Be sure mixing equipment is clean. Avoid waxed mixing containers.
2. Be sure surface is properly prepared. Use proper grit sandpaper for the type of coating
you are applying. (See coating manufacturer’s instructions for proper surface preparation.) After surface is prepared, avoid contamination—fingerprints, exhaust fumes,
rags with fabric softener (silicone). Coat within hours of preparation. After wet sanding,
rinse water should sheet without beading (beading indicates contamination). Wipe with
appropriate solvent and re-rinse until rinse water no longer beads.
Fish-eyeing in coating
Contamination of the coating or
surface or improper abrasion
for the coating.
Moisture in contact with hardener and metal container.
Hardener has turned red after several years storage.
Red color is a normal condition. It will not affect epoxy handling or cured strength. Avoid
using hardener for clear coating or exposed areas where color is not desired.
WEST SYSTEM User Manual & Product Guide ||
User Manual
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