Getting the Most from Target Coatings, Inc., Water Based Finishes

Getting the Most from Target Coatings, Inc., Water Based Finishes
Getting the Most from Target Coatings,
Inc., Water Based Finishes Using HVLP
Spray Equipment
Text and photos by Jerry Work
A common question among woodworkers coming into the small studio and gallery
where I design and handcraft fine furniture is, “How can I get the quality of finish on my
pieces that you do on yours?” They all know that even the most artfully crafted and prepared piece will look downright amateurish with a poorly applied finish or if the finish
chosen is simply not the best one for the piece. For many, finishing is a dreaded necessary evil or at best a mysterious process filled with failed experiments. I guess that is
why many advanced hobbyists and more than a few professionals revert to lathering on
oil based or wipe on poly-in-oil type materials. They may smell really bad and they not
like them very much, but they can at least achieve an “acceptable” look most of the
time.
I mean no disrespect for these finishes since applied correctly and used on the right
pieces they can produce a stunning finish worthy of the finest craftsmanship. However,
too often they are the finish of last resort for many and are poorly or inappropriately applied resulting in a far less than desired outcome. A statement I hear often from such
visitors is something like, “I
really love making furniture, but
I really hate the process of finishing it.”
Most have heard about or read
about water based finishes
sprayed on with High Volume,
Low Pressure (HVLP) equipment. They, perhaps like you,
intuitively think these finishes
and this kind of equipment
would help them do a far better
job of finishing, but they don!t
know enough about either to
make informed decisions.
When people look at examples like the Oregon Black
Walnut and burl pieces shown
on the previous page where
water based finishes were
polished to produce a beautiful soft patina, or other pieces
where water based finishes
were used to produce a satin
look (the piece to the right) or
a dead flat look, they find it
hard to believe that all of
these different looks can be
achieved with water based materials.
They also find it hard to believe that the
grain on darker woods can be enhanced
with water based finishes, or that lighter
woods can reveal so much beautiful figure without the yellow or amber colors
imparted by most wipe on or oil finishes.
When they see such examples they mistakenly think water based finishes must
be monolithic things unto themselves.
They don!t usually realize that there are
as many different types of water based
finishes as there are volatile organic solvent based finishes.
For example, the four shown here from
Target Coatings include shellac, lacquer,
varnish, and urethane, and these are just
a sampling of what is available.
The idea of water based finishes is appealing to most all of us for all the obvious advantages such as greatly minimized environmental assault compared to
volatile organic materials, lesser and less
harmful odors, easier and safer clean up
with just water, and so on. But, the lack
of knowledge of how to use them, which
to use where and when, and the mystery
surrounding applying them have been
stumbling blocks for many.
In this manual I am going to attempt to
remove these and other stumbling
blocks and try to make water based
finishes easier to understand and,
hopefully, an important part of your
woodworking future.
It is hard for me to talk about water based
finishes without also talking about systems for spraying them on, especially the
newer HVLP kinds of spray equipment. I
know that others have achieved good results brushing on water based finishes,
but I have not had much success doing
so myself. So, in this manual the focus
will be on applying water based finishes
with High Volume, Low Pressure (HVLP)
spray methods.
We will cover the differences between
turbine systems and conventional compressors using so called “conversion
guns”. We also will
explore issues like
how many stages a
turbine needs to
have, or what air
cap, needle and
nozzle to use, or
whether pressure pot
guns or gravity guns
are best, whether
“bleeder” or “nonbleeder” guns are
best, whether there
is any real difference
between the most
expensive HVLP
systems or the very
cheap ones, and so
on.
Before we begin,
though, a word about the spray environment is in order.
With any volatile organic material the atomized mixture can be very explosive
and when released directly into the atmosphere can cause known harmful effects to the environment and those who
inhale the fumes. An explosion proof,
properly filtered spray booth is a must
if you plan on spraying any volatile
organic compound.
With water based materials the spray
area requirements are very different. The
materials themselves are for the most
part environmentally benign. What little
over spray there is dries so quickly that it
simply falls to the ground as a fine white
powder that is easily swept up.
The photo here is of my finish room. I
have been spraying water based materials in this room on a nearly daily basis for
several years. It is separated from my
studio and small gallery area only by
double french doors. I do have a simple
filtered exhaust system, but it is there
mainly to clear the room of residual over
spray quickly because I most often am
shooting one piece while building others
in the next room.
I do always use a respirator. Even
though the water based materials have
little odor, I simply don!t want to put anything like that in my lungs. I suggest you
do the same.
You can see from the picture above that
the floor is clean, the walls are not
gunked up with old dried finish, and the
two sink areas need no covers to protect
them.
Unless you plan to spray pigmented water based materials, you can do so nearly
anywhere you can establish a clean, draft
free environment to work in.
I traversed the same set of questions you
likely now have when I began my process
of learning about water based materials
and HVLP spray methods. I made more
than a few mistakes along the way, mistakes that I hope to help you avoid.
One thing I want to make clear from the
beginning: long before I agreed to write
this manual for Target Coatings I purchased and used their materials in my
own studio enough to become convinced
that across the board they make some of
the best water based products available.
Others may also make fine water based
products, but the Target line is the one
that populates my finish room day in and
day out.
That was not always the case. I am constantly seeking new methods or products
that will allow me to build better quality
furniture faster so I can offer those ever
better quality pieces to my customers at
ever lower prices, what I call “increasing
the value proposition” for them.
Over the years I have tried a lot of different manufacturers! finish products. Some
I liked a lot at the time and with some
others I just could not achieve the result I
was after no matter how hard I tried.
The more I used the Target Coatings materials, the better the value proposition I
felt I could offer to my customers, so, as I
said earlier, they are the ones that populate my finish room today. The red and
white with blue stripe cans shown in the
previous picture of my finish room are
various kinds of Target Coatings water
based finishes I use every day.
Our Task
The task for this manual is to try to cover
five different kinds of water based finishes applied with five different types of
HVLP systems (pictured here and on the
next page). We will be exploring both
three and four stage turbine systems from
two different manufacturers, one with a
bleeder gun and one with a non-bleeder
gun.
In addition, we will explore three different
“conversion” guns from Asturo, one of the
premier conversion spray gun manufactures. We will be using two of their HVLP
guns, one with a gravity pot and one with
a pressure pot. We will also examine one
of their latest offerings called a “High
Transfer Efficiency” gun with a gravity
feed cup.
Accuspray three stage turbine and nonbleeder gun
Asturo gravity feed HVLP gun (above)
and High Transfer Efficiency gun (below)
Whew! All that!s before considering the
effects of different air cap, needle and
nozzle sets for each of these. And, we
need to cover this ground without this becoming some ponderous academic study.
We all do woodworking because we enjoy it so I will do my best to keep this light
and fun while still answering the questions most of you have.
Strap on your reading belt and let!s get
started.
Asturo pressure pot HVLP conversion
gun
Apollo 4 stage Turbine and Gun as they
sit in the compressor locker in my finish
room. This is a bleeder gun.
What are the differences
between these various
materials?
Let!s start by identifying what we mean
when we use terms like lacquer, varnish,
paint, shellac, urethanes and sealers.
And, what do we mean by “water based?”
I am no paint chemist so my definitions
will be those that make sense to me.
They may not be technically accurate in
all respects but hopefully will help you
sort this all out.
No one seems to know for sure which
kinds of finishes came first, but lacquer,
varnish, paint and shellac are all related.
They all originally were derived by dissolving either the resins
and saps from certain
trees or plants, or, in the
case of shellac the excretion from an insect, in
a solvent.
This mixture was then
applied to the surface.
As the solvent dried out,
the solids remained and
formed the “finish.”
For example, in the Orient a natural lacquer
was derived from the
sap of the Japanese
Varnish tree dissolved in
processed solvents we
now refer to commonly
as “mineral spirits”.
coat itself and every thing around it.
These resins were harvested and dissolved in a solvent, most commonly an
alcohol based solvent.
Lacquers were made from compounds of
cellulose, resin or lac. Lacquer made
from resins is usually mixed with turpentine which evaporates in air leaving the
protective coating on the surface. When
cellulose or lac is used they are usually
dissolved in alcohols or acetates which
also “dry” by evaporation.
What are called “spirit varnishes” are
made of resins dissolved in some quickly
evaporating liquid such as turpentine or
alcohol. What are called “oleoresinous
varnishes” are made of cooked mixtures
of resins and drying oils dissolved
in turpentine or
petroleum spirits.
They dry by both
evaporation and
by the hardening
of the resin-oil
mixture when it
combines with
oxygen in the air.
Photo of a person harvesting lac resin taken from
a publication of the Zinsser Co., a leading supplier of conventional shellac products.
In India and other parts of Asia the resin
came from the lac bug which in the larva
stage eats the sap of the Lac tree,
chemically alters it and then excretes a
reddish colored resin which it used to
More recently
other kinds of fossil, natural and
synthetic resins
have been used to
make shellacs,
varnishes and
lacquers, each
with unique characteristics.
For nearly a century synthetically derived
resins have been replacing the naturally
occurring resins as they are easier and
cheaper to produce and often exhibit
more consistent characteristics.
when to use something other than water
for clean up.
Add pigments to any of these and the result is generically called “paint.”
Be careful not to assume that just because these are “water based” materials
that you can thin them with tap water or
even distilled water. Often a special reducer is offered which will contain more
than just water. Use it when indicated
and only in the amounts indicated.
Confused yet? They certainly all sound
similar, don!t they? The good news is we
don!t need to know the intricacies of
each, only their properties as they apply
to woodworking and furniture making.
Water based finishes, whether they
are called lacquer, shellac, varnish, urethane or paint are finishes where the synthetic or naturally occurring resins have
been dissolved in compounds which
themselves are water soluble until cured.
The water replaces most all of the volatile
organic solvents which frequently are referred to as “thinners,” as in paint thinner,
lacquer thinner, and so on.
These are complex formulations and
you do not want to disturb what may
be careful balances of components by
simply diluting them with water.
Once these water based materials cure,
that is, they undergo a molecular cross
linking to change their fundamental
chemical nature, they usually become
quite impervious to contact with water.
This is unlike alcohol based natural shellacs and volatile organic based noncatalyzed lacquers which both remain
highly susceptible to re-dissolving when
they come in contact with their respective
solvents.
For water based finishes, clean up is also
accomplished with water as I am doing
here cleaning an Asturo gravity feed
HVLP conversion gun. While the water
will remove most of the residue, it may be
necessary from time to time to clean your
spray equipment with conventional solvents if you experience a build up of the
dried water based materials. Read the
product label to determine whether and
Rather than trying to distinguish between
the water based shellacs, varnishes, lacquers, urethanes and sealers by composition, let!s look at them in terms of their
finish properties, durability, and the conditions under which they are best used.
You will find a wealth of information on
the Target Coatings web site
(www.targetcoatings.com), some of which
will be repeated here for clarity.
We will start with shellac. Shellac
has been used for centuries as the primary protective finish for fine furniture,
decorative arts, and
a variety of industrial applications.
Shellac enhances
the natural beauty
of wood grains
without muting them
by obtrusive pigment blends.
Conventional wisdom dictates shellac
has to be cut or dissolved into denatured alcohol to
form a film and perform as a quality,
professional-grade
wood care product.
It turns out that is
not true.
Shellac, even shellac which has had the
natural waxes removed, can be cut into a
water suspension if handled and processed properly. In fact, shellac has been
and continues to be used in water solutions for fabric finishing, paper treatments, medical coatings and food-grade
films to ensure that the assigned substrate is well protected and safe from
contamination.
According to the Target Coatings literature, Oxford UltraSeal-WB™ WaterBased Shellac Sealer & Barrier Coat
(shown above) “...is the first truly successful water dispersed de-waxed shellac
system that looks and behaves identically
to alcohol cut shellac in terms of surface
wetting, color generation, burn-in and
overall depth and feel. Developed to be a
drop-in replacement for alcohol cut shellac for finishers who have concerns about
the use of alcohol in
environments that
are not flash-proof,
Oxford UltraSealWB™ can replace
traditional alcohol
cut shellac in all applications”.
This matches my
experience with this
product. I simply no
longer use the alcohol based shellacs
any more. I find the
Oxford water based
shellac performs as
well, pops the grain
as well and dries
faster and harder
than the alcohol
based shellacs I
used to use. It also
seems to me to
have a longer useful shelf life.
This Target Coatings product is a 25%
solids cut (slightly higher then a 2 pound
cut which is 21% solids) of de-waxed
shellac resin dispersed into a water vehicle. It has excellent substrate wetting capabilities, color, depth generation qualities and remarkable adhesion. In the Oxford line it is available in Blonde (clear),
Amber (the yellowing that is normally associated with alcohol bases shellacs) and
Garnet (which imparts a reddish cast
great for some darker and redder woods
such as cherry and walnut).
It can be used on wood, fiberboard,
sheet-rock, stone, glass and metal surfaces to act as a underlying sealer or barrier coat to ensure proper adhesion of
any water-based or solvent-based topcoat system. This is really important
when you want to stain wood or use an
oil to really bring out the
grain on darker woods like
Purple Heart. I have had
good success with several
different non-surface building oils once they dry completely and I over coat them
with the Oxford shellac.
While some have used shellacs as the
only finish on wood, and for centuries it
was considered a fine finish for furniture,
my experience is that the other coatings
we will explore in this manual perform far
better on furniture than just shellac alone
in daily living.
This product also works well
when you need to seal resinous woods like the blood
wood on this figured maple
and crotch black walnut
chess board with the inlaid
blood wood surround, or
woods which tend to weep
sap, such as pine or fir.
The shellac will raise the
grain so it makes for a good
sanding sealer as well, although not as
good from my experience as the Oxford
8800 sealer which is specially formulated
just for that task. In most cases if you are
shooting in a 70 degree room, the 8800
sealer can be sanded in an hour. The
shellac often takes longer to dry before it
sands as well.
If you have any question about the adhesion of your build and final coats due to
contamination, or wood type, or previous
finishes, I suggest you spray on the Oxford shellac as a first barrier coat since all
of the other water based Target coatings
will stick very well to the Oxford shellac.
For example, I admire the tenacity of
those who laboriously pad on layers of
alcohol based shellac in a process called
“French polish.” Done well the surface
can look spectacular, but just don!t spill
anything with alcohol in it or you might
wind up with a mess since the shellac will
easily re-dissolve in alcohol even years
later.
Water based shellacs are not as fragile,
but I don!t want that kind of risk for my
customers so the shellac remains a barrier coat, not a finish coat for my pieces.
Next let!s consider the Target Coatings
water based lacquer called “Oxford
Ultima Spray Lacquer (USL).
This is an ultra clear formulation of acrylic
copolymer resins and HAPS-free solvents. That is, it contains no hazardous
air pollutants.
It was developed to compete directly with
the nitrocellulose lacquers and has a
property unique among water based finishes from my experience in that it “burns
in” between coats. Most water based finishes sit on top of a previous coat. This
material actually “melts” into the previous
coat so all subsequent coats build to behave like a single unified coating just as
you get with nitrocellulose lacquer.
In fine furniture this means that you can
sand between coats to remove blemishes
or dust and not worry too much about cutting through an edge on the previous
coat. When you apply the next coat, the
broken surface simply melts together with
the new coat and the area of the coating
you knocked off with your overly aggressive sanding just disappears and blends
in.
This is NOT the case with many other
brands of water based lacquers I have
tried. In those cases, if you break
through the previous coat it will show
through in subsequent coats spoiling an
otherwise nice finish.
With those other brands I learned to be
very careful when sanding between coats
and often would not even approach the
edge where the finish is thinner and more
fragile. Sometimes I faced a dilemma
when a blemish or dust bump was close
to the edge. Should I try to sand it out
and risk knocking off the edge or “play it
safe” and leave the blemish in place?
Those are the kinds of trade offs that I
hate to make on one of my pieces. Remember the discussion earlier about constantly striving to increase the value
proposition for my customers (increasing
quality at lower cost)?
So, when I first learned about the Oxford
USL product I was thrilled to find that I
could sand out the imperfection even if it
was near the edge because the next
coats would burn in and even overly aggressive sanding would not leave a visible mark.
I am not suggesting that you become
cavalier about your sanding between
coats, just that, if you do happen to knock
off an edge, it is not the end of the world.
This is a very forgiving product that is
really good to use day-in and day-out.
This product has 30% solids
and is stronger than the nitrocellulose lacquers that for years
have been the main stay of
commercial furniture manufacturing.
If you are familiar with viscosity
rating in terms of how long it
takes for a specified amount of
this material to flow out of a
hole of a certain size, a so
called “Zahns cup” shown at
right, this material has a Zahns
#2 rating of 30 to 35 seconds.
The American National Standards Institute (ANSI) publishes a standardized series of tests that manufacturers can use to rate their products. ANSI
Standard 161.19.3 pertains to chemical
resistance. Using test procedures which
meet this standard, Target Coatings determined that the Oxford USL is resistant
to water and most common household
chemicals.
Water, glass cleaner, all purpose cleaners, coffee and olive oil left standing for
24 hours had no effect on the finish.
Lacquer thinner and orange juice slightly
softened the finish but it fully recovered
when they were removed. Acetone and
denatured alcohol resulted in slight to
moderate swelling, but passed the test.
When exposed to 120 degree temperatures for two hours, there was no discoloration, blistering or film failure.
This is the “swiss army knife” of water
based finishes and a very good one to
learn on. Based on my experience with
other manufacturers’ water based acrylic
lacquer products I would rank this one as
top of the heap. You
just can’t beat that
burn in quality.
It also is water clear
so you really see the
wood itself.
On darker woods it
does not blush or
leave a gray cast the
way other products
of this type that I
have used do.
Even so, by itself it
does not bring out
the best in the darker
woods as the clarity leaves them a bit lifeless. I suggest you may want to pop the
grain with an oil and/or the shellac first as
I did on this gong stand made from Brazilian Cherry, Blood Wood and Black Walnut.
Next let’s move to what I think is one of
the least well understood finishes, the
Conversion Varnishes.
Target Coatings calls their water based
conversion varnish “Emtech 8000”. It is a
pre-catalyzed material that is ideal where
exceptional water resistance, UV stability
and hardness is desired in a clear, nonyellowing finish.
find very appealing, especially on darker
woods. Even though it is pre-catalyzed,
it has a 12 month shelf life.
If you like a piano or guitar like gloss finish, you can’t beat this conversion varnish
after it has been buffed and polished as
we will describe later. It simply will knock
your sox off, especially if you apply it to a
darker wood like true mahogany or black
walnut or any member of the rosewood
family. Stunning results can be achieved
quite easily.
It has a viscosity about like the lacquer
(35 seconds in a Zahns #2 cup) so you
can spray it with the same air cap, nozzle
and needle making it easy to mix finishes
on the same piece. Lacquer the horizontal and interior surfaces and use
the conversion varnish on the top. It
also is 32% solids and weighs the same
8.6 pounds per gallon.
Do you hear counter tops, exterior
doors and marine applications in this
description? I surely do and that is
where this material really excels.
Because it is pre-catalyzed there is no
need to measure out and add a “part b”
or a separate catalyst as other manufacturers’ products require. It imparts a soft
feel and color tone usually associated
with solvent based varnishes that most
Where it really shines is in its water and
chemical resistance. ASTM, another
standards and testing organization, publishes a chemical resistance standards
procedure identified as ASTM D3023-88.
Following that measurement procedure
the Emtech 8800 conversion varnish
scored a 5 (no effect) when subjected to
water, glass cleaner, all purpose cleaner,
vodka, coffee, coke cola, mineral spirits,
and diesel fuel. Iodine and denatured alcohol had a very slight stain/effect. Even
such harsh chemicals as acetone and
lacquer thinner showed only a slight effect. A permanent black marker did result
in a moderate stain.
So, when you talk about resistance to
most common household chemicals, this
product is hard to beat. It also flows out
wonderfully as we will see in the actual
application tests.
Where the surface will take a beating, this
is the coating to use, like for the counter
tops on the loft kitchen shown in this
photo.
Once cured, it cross links and becomes
very hard so it is not easy to remove and
takes a lot of sanding later if you plan to
refinish.
Again, think counter tops, exterior
doors, lawn furniture and marine applications.
This brings us to the Urethanes. In
the Target Coatings line these are called,
“9000 series super-clear polyurethane
one-part copolymer” materials or the
“9300 series Polycarbonate Urethanes.” I
dare you to say either of those fast five
times!
The 9300 Polycarbonate Urethane shown
to the right is the hardest of all the water
based coatings with which I am familiar,
does not require any additional cross
linkers, catalysts or hardeners, and is
ideal for use where scratch resistance is
the primary objective. It is also very
clear, does not yellow, and dries quickly
at room temperature. Think of the applications where you previously might have
used solvent based polyurethanes (brush
marks and all) and consider substituting
this product for outstanding results.
You can use it successfully over grain fillers and high solids sanding sealers
where you want what is called a “tight finish,” meaning where you want the grain
pores and other surface imperfections to
be all filled in for a really smooth glasslike finish. Once fully cured (which can
take a couple of weeks or more) it also
will buff to a very high gloss, such as you
will find on the finest guitar bodies and
pianos. It will be similar to
the example shown on the
left where blood wood and
maple burl inlays are set into
cherry and the whole thing is
buffed to a mirror like shine.
It is a knock out finish and
one that I guarantee your
friends will not be able to resist touching just to see if it
really is wood!
I often use this finish on what
I call “reflection panels.”
These are book matched burl
surfaces polished to a high
gloss and displayed upright
on a stand. They usually are
A couple of examples of polished
burl panels.
about 12 to 16 inches wide and high.
Put a candle in front of them, lower
the room lights and the candle flame
reflecting off of the surface is almost
magic.
Thanks, “9000 series super-clear
polyurethane one-part copolymer!”
With the various Target water based
coatings now in mind, it is time to
move to applying them and testing
the five different HVLP systems to
see which works best with each different coating.
Before we do, however, we should
spend a moment talking about properly preparing the wood to receive the finish. That is what we will do in the next
chapter.
Preparing the wood for
the finish.
some touch skill required to do it correctly.
It is always fun to watch visitors who
come into my small gallery and studio as
they approach the fine furniture I design
and hand craft. Unlike those who stand
back to look at flat art or sculpture, those
who look at furniture most often move
quickly to a piece and invariably move
their hands across the surface while they
take in the piece with their eyes from up
close, just like in this photo. They might
pause to ask if it is OK to touch the
pieces first, but once they know they can,
the tactile urge takes over.
At some point the question is always
asked, “what kind of finish do you use?”
It does not make any difference if it is an
oil and wax finish or a nicely applied water based finish like those we are discussing here, they seem to think the silky tactile feel is somehow accomplished by the
application of a magic elixir.
While the choice of finish material is important to achieving the desired overall
look and feel, an equally important factor
is how the raw wood was prepared before
the application of the finish material.
In building fine furniture I find that more
than 50% of my time goes into sanding,
final assembly, buffing and polishing.
This is most often more than twice the
amount of time that it took to machine all
the component parts of the piece. Yet,
scraping and sanding processes, tools
and materials are seldom as carefully
chosen as are the machines that cut the
wood components in the first place.
Scraping can produce outstanding results, but there is a learning curve and
I find that most wood workers sand rather
than scrape their wood to get it ready for
finish. That is what I do most of the time.
Contrary to what some say, I have found
proper sanding produces just as fine a
surface after the finish is applied as
scraping and is far more controllable for
most, so that is what we will concentrate
on here.
Sanding is the use of some kind of hard
material to abrade the surface fibers of
the wood shearing them off to leave a
smooth feel to the surface. Simple to
say, but hard to do well. As you abrade
the surface, you also scratch the surface.
If those scratch marks are large enough,
they will detract from rather than add to
the appearance of the final product.
So, the trick is to learn how to use smaller
and smaller particles of the hard material
to remove the larger scratches and leave
smaller and smaller scratches until they
no longer are visible and to do so in such
a way that the entire surface of the finished piece is uniformly treated, corners
and all.
Initially, this work was done laboriously by
hand by scooping up naturally occurring
small rock particles (sand) and rubbing
them over the surface with animal skins
or cloth. Later, means were found to adhere the sand to a paper or cloth backing
and what we today call “sand paper” was
born.
Also, various power tools were developed
to greatly reduce the manual effort required to move the abrasive over the
work piece. Seven different types of
possible to man made materials like silicone carbide and aluminum oxide engineered with a very high uniformity in particle size.
The backing materials can be various
kinds of paper derivatives, or various
kinds of cloth materials or man made
screens or combinations of all three.
There may be other materials added to
the abrasive surface like stearates to help
prevent loading of the paper with small
particles of wood fibers and the resins
that naturally occur in the wood.
Stearates are derived from stearic acid, a
white crystalline fatty acid C18H36O2 obtained by saponifying tallow or other hard
fats containing stearin. They're a little bit
like soap. The sanding grit and dust does
not stick to the stearates so it keeps the
paper from clogging longer.
But, there is a very real
downside to using stearated
sand paper on wood you plan
to finish with water based materials.
“sanders” that are in use in my studio are
shown here. Some move the abrasive in
a circular motion like a grinder, some in a
linear motion, some in an arc, and some
combine various of these to create complex movement patterns, like the so
called “random orbit” sanders. The objective is to smooth the surface of the
wood while minimizing the scratch marks
left behind.
The abrasive particles can be anything
from natural materials like garnet and
diamonds that have been carefully processed to be as even in particle size as
No matter how hard you try
to clean it off, some of the
stearates may remain imbedded in the
wood and it most likely will cause fish
eyes in the finish that are very hard to
remove. If you suspect the wood has
been exposed to stearates, then seal it
first with shellac before continuing on
with any of the other water based materials.
To add to the confusion surrounding
“sand paper”, there are three different
“standards” applied to describing the size
of the abrasive particles. The US grades
are called “CAMI”, the European grades
are identified as “FEPA” and in Japan the
grades are identified as JIS.
The table lists how these different size
grades relate one to another and the actual size of the particles in microns. In
courser grades they are quite close but
as you move to the finer grades the differences become greater.
GRIT COMPARISION CHART
MICRON
US CAMI
500
430
410
350
320
300
270
260
250
210
197
192
177
156
149
140
127
116
97
93
78
66
60
52
46
42
40
35
30
28
25
21
18
15
13
10
8
7
6
36
40
FEPA 'P'
(Festool)
JAPAN JIS
36
36
I use Festool sanders as I find them the
very best in every category that is important to me and my work so those are the
ones you will see in the pictures here.
However, many manufacturers make different kinds of sanders so use what you
have.
To take maximum advantage of the
benefits from each of these ways different
sanders move the abrasive, you will want
to add different types of sanders to help
you achieve the results you are after.
40
50
40
50
50
60
60
60
70
80
80
80
100
90
100
120
100
150
120
180
220
240
280
320
150
180
240
280
320
360
400
500
360
400
120
150
180
220
240
280
320
360
400
500
600
800
1000
1200
600
800
1000
1200
1500
2000
2500
500
600
700
800
1000
1200
1500
2000
2500
3000
It is not as important to know these differences as it is to recognize how the abrading materials you are using have been
graded. This is important because in order to achieve a desired very smooth final
finish you need to progressively “sand”
the finish with finer and finer grits both
before you apply the finish and often afterwards as well. You don!t want to be
inadvertently jumping back and forth between grading standards or you could be
moving from a finer to a courser grit without knowing it.
If you can only have one, then the most
flexible would be the random orbit style
sander. Even better would be a dual
mode sander like the Festool RO150
shown here which
can be switched
between a random orbit motion
and a rotary motion with a moving
pivot point. You
can do a lot with
just one of these.
In rotary mode it
also is a great
buffer/polisher, as
we will see later.
Other types of sanders will reach into
corners better, or do a better job on some
surfaces, or may be faster, but, if you only
have a random orbit or dual mode
sander, it will work just fine for getting
your pieces ready for finish.
The way I work, I use different combinations of my sanders depending on what I
am doing. In furniture designs where I
want to carve out a section like a chair
seat, or where I want to instill an Oriental
feel by curving the under sides of top or
shelf components, a process I refer to as
“boating,” I like to start with a rotary motion sander with grits from 36 to 60 since
complex curves can be roughed out easily and quickly. Then the rough shape
can be finished with one of the less aggressive random orbit style sanders using
grits from 80 progressively up to 220 to
400 on soft woods and up to 600 to 800
on hard woods.
Hard woods show fine scratch marks
more than soft woods so you need to go
to smaller grits before the scratch marks
are no longer visible.
For rail, style and panel work I like to first
finish sand the panels up to 600 to 800
grit before a component like a door or
side is assembled. I sand the edges of
the rail and style pieces after the profile
about the faces until you assemble the
R&S component.
Once you do the glue up, now sand the
faces to the rail and stile pieces to be
flush and flat using a progression of grits
from 80 up to 400 to 800 depending on
the hardness of the wood. If you have a
large flat orbital sander like the one
shown here, they work well as it is easier
to keep them flat on the R&S faces than
to try to keep a random orbit sander flat
on such surfaces. They also work well
for the edges and to break the sharp 90
degree corner between a face and an
edge.
For solid woods be sure to spend much
more time on the end grain as it is harder
to sand and takes quite a bit longer than
the faces or edges. To look and
feel right the end grain must be
very smooth before you apply
the finish.
A good progression for most
applications is to use 80 followed by 120 followed by 180
followed by 240 followed by 400
followed by 800 if necessary.
Don!t worry about using exactly
these grit numbers in your progression, just somewhere in
these ranges.
The trick is to place a strong
side light shining across your
work piece. This will show
up scratch marks and surface
imperfections that you cannot easily see with top light.
has been cut but before glue up to 220
grit to make sure all the chips and rough
edges are removed. Don!t worry much
Start by removing all the surface imperfections with the 80
and 120 grits. Don!t go any finer until all
the surfaces are smooth and flat. From
there on all you are going to do is use the
next finer grit to remove the scratch
marks left by the previous grit.
Don!t tip a random orbit sander to make it
cut more aggressively or you will make
scratch marks that are harder to take out.
In the long run you will actually slow
down your sanding process, not speed it
up, by tipping the RO sander.
I know most will get impatient as it can
take quite a while to really get a piece
smooth and flat and ready for finish, but
the payoff is worth the effort.
When you are convinced that you can no
longer see any scratch marks or other
surface imperfections, move your hands
over the piece. Your hands can often feel
things your eyes miss.
Now blow off or wipe off all the sanding
dust. Use a moist rag or paper towel to
help, but do NOT use tack rags as they
can contaminate the surface and cause
the water based finishes to crater or fish
eye. Make sure your hands are free of
oils as oily finger prints may also disturb
the flow out of the water based materials.
The next step is to spray on the sealer
coat to raise the grain and create a good
bonding surface. Once that dries, resand the piece with 220 or 400 grit just
enough to get it good and flat. You don!t
need to sand through the seal coat, just
knock off the raised grain and make a
nice surface for the build coats to flow out
over. Use a moist clean rag or paper
towel to remove the sanding dust.
The build coats do what the name implies, they build up the film to the desired
thickness. You can sand between coats if
you get an imperfection or dust nodules,
but you really only need to sand the final
build coat. You want that last build coat
to be nice and flat before you put on the
final top coat. Wipe with the clean moist
rag again. The objective is to get the final
top coat to flow out to be as glassy
smooth right off the gun as you can make
it.
With the prep process in mind, let!s talk
about the HVLP equipment with which we
will apply these finishes.
HVLP for Applying Water
Based Finishes
Commercial High Volume Low Pressure
spray equipment was first developed by a
French company several decades ago.
They were trying to find a way to reduce
the over spray problems associated with
conventional spraying processes which
use relatively high pressure air (40 to 60
or more psi) to atomize the finish
and deliver it to the work piece.
were constructed with a variety of filtering
or collection methods. Some used waterfalls to capture the over spray in a water
bath where it could then be filtered and
disposed of. Electrostatic and other kinds
of air filters have been used along with
many other means of trying to capture the
over spray once it was released into the
environment of the spray booth to try to
keep it from going freely into the atmosphere.
High pressure guns do a good job
atomizing so are capable of producing a very nice, smooth finish
on most materials. Unfortunately,
by delivering the atomized finish
with that much force, up to 80% of
the finish winds up bouncing off of
the work piece, or never reaching it
in the first place, and instead forms
a fog in the air called “over spray.”
If the solvents or the finish materials themselves are toxic, by being
finely atomized they can easily be
inhaled and damage the lungs of
anyone near by. They also easily
combine with other elements in the
air to form air pollutants which
have been shown to be harmful to
the environment.
If you simply try to reduce the air
pressure used with conventional spray
guns. you also reduce the atomization
and the result is a greatly degraded surface finish.
Industrial users of spray equipment for
decades tried a variety of means to capture the harmful over spray before it was
released into the atmosphere or was inhaled by people. Elaborate spray booths
Here is a picture of the finish room
we will use for this manual showing
the various Target Coatings materials
and some of the HVLP equipment we
will use.
Obviously, with up to 80% of the material
coming out of the gun going into over
spray and as little as 20% reaching the
intended work piece, the cost of the over
spray was also a substantial issue.
HVLP systems try to atomize the finish
material with a high volume (100 or so
CFM) of low pressure air (under 10 psi at
the air cap). The lower pressure means
that up to 80% of the finish material
reaches the surface of the intended work
piece and only around 20% goes to over
spray so the benefits are substantial.
be drawn from the bottle, mixed with the
air stream, and sprayed out the nozzle.
Not very elegant, not very effective, but it
did work, sort of.
The problem has always been achieving
an atomization quality approaching or
matching conventional high pressure
spray equipment. Until fairly recently that
proved to be an illusive goal.
Modern HVLP turbine systems also use
a motor turning a turbine but that is about
where the similarity stops. In HVLP turbines there may be three or more turbine
units all connected to the output shaft of
the motor, each boosting the output of the
stages before them.
Since the work done by the original
French company, a number of firms
around the globe have developed their
own HVLP equipment, often tracing their
roots back to that original innovator.
The innovation was the use of a turbine
to generate the high volume of low pressure air instead of a compressor which
generates a relatively low volume (6 to 20
cfm) of high pressure air (40 to 100 or
more psi).
You can think of a turbine much like the
output from a vacuum cleaner. There a
motor turns a turbine to generate the suction and the air is exhausted after passing
through bags and/or filters which trap the
particles picked up in the suction air
stream.
In fact, from the 1950!s on many canister
style home vacuum cleaners offered a
simple kind of HVLP spray gun as an option. Usually it was nothing more than a
hose that attached to the exhaust port.
On the other end of the hose was a bottle
with a lid containing a large and small air
chamber. Where the transition occurred
between the large air chamber to which
the exhaust hose was attached and the
small air chamber to which a nozzle was
attached, a venturi effect was created.
As the air speeded up moving from the
large to the small air chamber, fluid would
That air flows through a hose and into a
specially designed spray gun. These
guns have much larger internal air passages than conventional high pressure
spray guns, and different means of moving the finish material through the metering needle and out through the nozzle.
The air flows through a specially designed air metering system called an “air
cap” which serves two functions. One
function is to mix air with the finish material, atomizing it and delivering this atomized mixture to the surface of the work
piece.
The other function is to flow through a different pathway to define the shape of the
atomized finish material air stream on its
way to the work piece. This is called
“shaping the fan pattern” since the most
common means of delivering this atomized air stream is via a flat wide pattern
much like the shape of an unfolded hand
fan as is shown in the pictures on the
next page.
This fan shape can be directed to be
horizontal or vertical and in some guns
can also be at any angle. As the spread
of the fan is narrowed, the pattern becomes less flat and more like a cone
shape. Most guns provide a means of
controlling the shape of the fan all the
Note the difference in fan shapes. The upper flatter fan
shape is from the Asturo HVLP conversion gun and the
lower, more rounded fan shape is from the Asturo HTE
conversion gun. Both are shown spraying water.
way from nearly a stream to a very flat,
very wide fan pattern.
The way the portion of the air stream that
is used to atomize the finish material
works and the way the portion of the air
stream that is used to alter the shape of
the fan works is basically how one HVLP
turbine gun differs from another.
More recently the companies
working to develop efficient
HVLP spray equipment that
rivals or even surpasses the
finish quality of high pressure
spray guns have developed
special spray guns. These
receive high pressure air from
conventional compressors
and convert this air stream
internally into a low pressure
atomized stream that reaches
the work piece with similar
velocity and similar transfer
efficiency to the HVLP turbine
guns. Not surprisingly these
are called, “conversion guns”
in the HVLP world.
There are two different ways
both the turbine guns and the
conversion guns move the
finish material into the atomization air stream. One is
called “gravity feed” where the
the cup that holds the finish
material is above the gun so
the finish material can flow by
gravity into the nozzle chamber and then into the atomization air stream. The other is
called a “pressure pot” system. In that case the finish
material is held in a sealed
cup below the gun and a
small amount of the incoming
air stream is directed into the
top of that cup, pressurizing
the contents and forcing it up through a
tube and into the atomization air stream.
Both have their advocates and detractors.
In this manual we are going to examine
the performance of five different HVLP
guns: a 3 stage HVLP turbine and pressure pot gun manufactured by Accuspray,
a 4 stage HVLP turbine and pressure pot
gun manufactured by Apollo, a pressure
pot HVLP conversion gun manufactured
by Asturo, a gravity feed conversion gun
from Asturo and one of their latest offerings, what they call a “high transfer efficiency” gun.
Several of these are in use in my studio
on a daily basis so these are not photo
props, they are working tools and show
the scuffs, scratch marks and gunk one
would expect would accumulate in real
world usage.
Let!s look at the air caps on these different guns to see how each controls the
Pressure pot gun shown above and a gravity feed gun is
shown at left. Both are Asturo HVLP conversion guns.
This photo shows (left to right) the Apollo
turbine pressure pot gun, Asturo HVLP conversion PP gun and Accuspray turbine PP
gun.
atomization air stream and shapes the
fan pattern. These become very important in understanding how the different
guns perform in terms of applying finish
to the work piece and doing it well with
minimum over spray.
The photo below shows the air cap on the
looks much like the Apollo air cap from
the front, but we will see in a
minute that they are very different from the rear.
These are four different approaches to try to achieve a
similar outcome, obviously the
result of different engineering
approaches and experiences.
Apollo turbine gun. Around the center of
the nozzle is an opening through which
the atomization air flows. Contrast this
with the Asturo HVLP gun (below) which
uses the eight small holes outboard of the
nozzle to atomize the air and the Asturo
HTE gun to the right (marked K1/S) which
uses only four small holes outboard of the
nozzle.
The Accuspray turbine gun air cap, the
gold colored one shown above right,
From looking at these pictures it
should not be surprising why the
cheap HVLP guns, whether turbine
or conversion guns which are often just
knock-offs of one of these four, usually
don!t produce anything remotely like the
outcomes from one of the guns from
these and other premier manufacturers.
If they are just copies without any understanding of the underlying engineering
trade offs, the results would likely vary
widely, and they do.
Remember the difference in fan shape
between the Asturo HVLP gun and the
Asturo HTE gun? Could you tell just by
looking why one would produce a flat fan
and the other a softer, rounder fan? I
sure can!t.
from exiting around the nozzle forcing it
through these eight small holes.
Now look at how the ring machined into
the back side of this air cap that surrounds those eight small holes serves to
seal the atomization air off from the fan
control air.
Let!s look at the back side of the air caps
and the front side of the guns with the air
caps removed to see the incoming air
passages.
The picture below shows the business
end of the Asturo guns with the nozzle in
the middle and the fluid metering needle
Look again at the photo to the left and
see how the outer holes provide the
fan control air and the inner holes provide the atomization air. No accidental
engineering here.
at the center of the nozzle. Both the
HVLP and HTE guns look similar to this
photo.
Above and to the right is the back side of
the air cap on the Asturo HVLP gun. See
how the eight small holes are formed in
milled recesses and how the larger hole
inside those recesses seals the air off
Now look at the Apollo turbine gun pictured on the next page. The back side
of the air cap is shown at 11:00 and
the front side of the gun where the air
cap attaches is shown lower right in
the upper photo. The plate with the
four dimples and the slots sitting in
front of the machine brass housing is
spring loaded out against the back side of
the air cap which is held in place by a
threaded ring which screws onto this
brass housing.
The dimples engage either one pair of
the six outer recesses or the two air passage holes as the air cap is rotated relative to the gun body. When the air pas-
sage holes are aligned with either the
horizontal or the vertical slots in the
spring loaded plate, air flows out through
the fan control holes on the front side of
the air cap shown here creating a flat fan
pattern. The width of the fan is controlled
by how much air is admitted through the
fan air control valve on the back of the
gun.
When the air cap is rotated so those
air passage holes are blocked by
one of the dimples, then no air is
admitted to the fan control holes on
the front of the air cap and the fan
turns into a cone shape whose size
is determined by the fan air control
valve.
Back side of air cap above
Apollo HVLP turbine gun
The total volume of air available for
either fan control or atomization
comes through the hole on the left
side of the picture, bottom left
(which is actually at the top of the
chamber. The gun is shown on its
side here.)
Here is the same thing for the Accuspray
gun. Again this photo is taken with the
gun on its side. The air available for fan
control passes through the elongated slot
at the left side of this photo while the at-
Front side of air cap
Front of air chamber showing nozzle
omization air flows through the four center slots. A rubber gasket allows the air
cap to seal these two chambers off from
one another on the back side.
The photo below shows the front side of
the air cap. The atomization air flows
past and around the nozzle and exits
through the large center hole. The fan
control air exits through the two small and
two larger holes towards the outside of
this air cap.
As you change the amount of air coming
through the fan control
holes with the fan air
control valve on the gun
body, you change BOTH
the shape of the fan from flat to cone shaped
- and the size of the fan.
As we saw, on the Apollo
gun the size of the fan is
controlled by the fan air
control valve on the gun
body, but the shape is changed only by
rotating the air cap into one of the eight
settings established by the dimpled
spring loaded plate that is pushed against
the back of the air cap.
The result is that with any of the Asturo
conversion guns, or the Accuspray turbine gun you can rotate the air cap to position the fan anywhere you want it. With
the Apollo gun a flat fan can only be horizontal or vertical since positioning the air
cap on either diagonal causes the shape
of the fan to change from flat to conical.
When I first saw an Apollo gun, I thought
this would be a problem. In real world
use it seems to be a non-issue.
From my testing, all five guns provide
good fan shape and size control, but the
Asturo guns control the fan in a more linear fashion and provide finer control over
both shape and size of fan than either of
the turbine guns.
I find fan control on the Apollo gun to be
a bit better than on the Accuspray gun.
A bigger difference in real world use is
the shape and fill of the fans produced by
these different guns. Here, the Asturo
HTE gun wins hands down in my judgment while the Apollo turbine gun comes
in a close second over the two Asturo
HVLP conversion guns.
After spraying all five
guns, I concluded that
the Accuspray gun fan
fill was just not as even
as with the other four.
I have owned the Accuspray gun longer and
used it far more than the
others. I wouldn!t even
want to guess how many
zillion gallons of different materials have
passed through that gun. The results
have always been acceptable to me so
I!m not sure the difference in terms of final finish is as great as I see in terms of
the evenness and fill of the fan patterns.
As we will see when we get to the next
chapter on the performance of these five
guns, clear favorites did emerge.
How the guns perform in
real world use
Over several days I shot test panels of
different kinds of hard and soft woods
along with baltic birch and oak plywood
panels using all five guns, two different
sealers, and three different top coats.
I did not shoot every possible combination with every gun but I did shoot enough
of them to reach some definite conclusions, both about the guns and about the
materials.
To test my opinions I also set up a focus
group of people who had never used water based materials or HVLP systems before. They were made up of advanced
amateurs and working professionals
alike.
Following an hour or so of background
explanation on the various water based
materials, how the different guns work
and how to adjust them, they were turned
loose in the finish room with test panels
they had individually prepared.
They shot different water based materials
with different guns throughout the day. At
the end of the day they rated each. I did
not tell them ahead of time anything
about the conclusions I had reached.
In most cases their consensus opinion
was the same as mine, but one very major difference did emerge. I will note this
and other differences as we proceed.
All Do a Good Job
Over all, this was the take away message
for me. All of these systems, whether
turbine or conversion gun, whether three
stage or four, whether “true” HVLP or the
high transfer efficiency type, are capable
of laying down an exceptional finish using
the Target Coatings water based materials. Personal preference and previous
experience enters into why one person
likes one spray system better than other,
but overall you just can!t make much of a
mistake no matter which system you select.
Air Matters
The first observation I would make is that
air matters. The more air available for
atomization the more controllable the fan
and the better the resulting finish.
This played out most dramatically between the turbine systems. It did not
matter whether I attached the Apollo or
the Accuspray gun, the four stage turbine
produced a superior result for me over
the three stage turbine. That was not the
consensus opinion of the focus group,
however. The three stage and four stage
systems were very closely ranked by
them collectively with half rating the three
stage turbine system either first or second.
One of the focus group members brought
a new Fuji three stage turbine system so
we wound up with two three stage and
one four stage turbine for comparison by
the focus group. I only used the Accuspray and Apollo units for my testing.
Most turbine manufacturers use the same
turbines and motors and I did not have a
four stage Accuspray turbine for comparison so I can!t say if there is any real difference between manufacturers, only that
the four stage unit did a better job than
the three stage unit in my hands.
I did put both the Apollo and the Accuspray guns on the three stage Accuspray
turbine as well. The performance of both
fell off observably for me from what they
did when attached to the four stage turbine. But, as noted, the focus group did
not reflect that in their preference rankings.
In both cases I found the Apollo gun produced better results than the Accuspray
gun. Remember that I have owned and
used the Accuspray gun longer and always found the results to be acceptable,
but I was really impressed with the results
from the Apollo gun across all the finish
materials.
It is my choice for the turbine guns and
was also slightly the choice of the focus
group.
The Apollo gun does have significant
drawbacks on paper relative to the Accuspray gun. First of all, it is a “bleeder
gun.” That means air is passing though
the air cap all the time whether you have
pulled the trigger to allow finish material
to enter the air stream or not.
The Accuspray gun is a non-bleeder gun
which means that air only passes through
the air cap when the trigger is pulled.
When the trigger is not pulled a valve inside the turbine unit itself releases the
pressure so as not to over tax the turbine
or motor units.
A gun that passes air through the air cap
all the time should be a real bummer as it
portends the possibility of blowing dust
and gunk all over your freshly sprayed
work pieces. In actual practice, it turned
out not to be the issue I thought it would
be.
I did connect the Apollo turbine to a remote control so I could switch it off easily
whenever I needed to, but the bleeder
issue did not rise to the level of importance where it mattered much anyway.
The second paper disadvantage of the
Apollo gun over the Accuspray gun is in
fan control. Remember from the earlier
pictures that the Accuspray gun allows
continuous control over both the shape
and size of the fan no matter what the
orientation of the fan pattern. The Apollo
gun only allows you to select flat or conical fan shapes by rotating the air cap
while you can alter the size of the fan via
the air valve on the gun body.
Again, in the real world this proved not to
be much of a difference, at least to me.
The Apollo gun simply performed better in
my hands than my old trusty Accuspray
gun.
Back to the “air matters” point. When using the three conversion guns (two HVLP
and one HTE) again the gun which
worked at higher pressures and more air
flow - the HTE gun - produced better results for me. But, that was not the conclusion reached by the focus group
members. They collectively ranked the
HTE gun lower than I did and generally
preferred the HVLP gun to the HTE gun.
The difference I observed was not dramatic but it was a difference I could observe across the board with the different
finish materials. The fact that I saw that
difference and found it mattered and the
focus group collectively did not indicates,
I think, a difference in our respective experiences with spray on finishes. The focus group members for the most part had
little spray experience and none with
HVLP.
The difference in performance I observed
between the HVLP gun and the HTE gun
has a lot to do with the very different fan
pattern created by the HTE gun. The fan
was rounder, softer and fuller no matter
which material I was spraying. Even
when I dialed the fan size way down, this
rounder pattern remained.
the tests for this manual, that soft pattern
laid down a consistently even film with
less wetting of the overlap areas than I
experienced with the HVLP conversion
gun.
The Apollo gun shown below produced a
sharp fan that was also well filled in the
center. It looks lighter in this photo because I had the fluid delivery turned
way down. While it looked less well
controlled coming off the nozzle, by the
time the material reached the work
piece the results were only a shade
behind the Asturo HTE gun, about
Asturo HTE gun
The round, soft and full fan pattern produced
by the Asturo HTE conversion gun produced
outstanding finish results with all the different
finish materials. The Asturo HVLP gun fan pattern, shown below is sharper edged and
somewhat harder, but also produced very nice
results.
Apollo turbine gun fan pattern
even with the Asturo HVLP gun and better than the Accuspray gun.
The Apollo gun is the only one that
does not require changing air caps
when you change nozzle and needle
sets. All the others provide recommendations on matching the air cap
nozzle and needle sets.
Asturo HVLP gun
In spraying the various test panels and
the furniture pieces I finished as part of
What I found is that by changing the
Accuspray gun to a larger air cap than
the factory recommends for a given
material viscosity, nozzle and needle
size, the resulting finish improved noticeably. While I don!t know it for a
fact, I speculate that this again relates
to the “air matters” point as the larger air
cap flows more of the available air than
the smaller one does.
mixed with the atomizing air and delivered to the work piece.
I did not find the same thing true with the
other guns. With those, I would stay with
the recommended air cap sizes for each
nozzle and needle set.
You can unscrew the cup from the gun to
throughly clean it when you need to. A
short brush makes scrubbing the inside of
the short fluid path a simple chore you
only need to do once in a while.
Bottom line, by my subjective
opinion the guns finished in order of Asturo HTE, Apollo turbine, Asturo HVLP, Accuspray
turbine. The collective opinion
of the focus group had the guns
finishing in the order Asturo
HVLP, Apollo turbine, Accuspray
turbine (nearly tied) and Asturo
HTE.
Water based materials do not set up in
the gun so you do not need to clean the
gun until you are through shooting for the
day. That really saves a lot of time.
Most of these water based materials will
set up fast enough on the work piece to
I found a significant preference for the
gravity feed guns over the pressure pot
guns. Because of the very short fluid
pathway, shown by the arrow in the picture to the right, they are faster and easier to clean. You can just unscrew the top
from the fluid cup above the gun and
empty remaining material right back into
its container. Then do a simple water
rinse of the cup while it is still on the gun
and let water flow through the fluid chamber and out the nozzle either with or without the air hose attached.
Now just filter in the next material, do a
quick spray to clear the water out of the
nozzle chamber, and you are ready to
shoot again. Changing from one material
to another couldn!t get much easier than
this.
The finish material flows by gravity down
into the nozzle chamber and out the nozzle when the trigger is pulled. There it is
Short fluid pathway simplifies cleaning
on this Asturo gravity feed HVLP gun
re-coat after only 20 to 30 minutes so it is
common to do all of your finishing on a
project in just part of one day.
I also found the gravity feed guns more
comfortable to use. They only can be
used for horizontal or vertical surfaces
and obviously can!t be used upside down
or tilted too far over as the lid on the jar is
vented to the atmosphere so finish materials could leak out that vent if the gun is
inverted too far.
does allow the user to adjust pot pressure
which the others do not.
When the trigger is pulled the finish material is forced by the pressure in the cup
up through a tube inside the cup and into
the bottom of the gun. From there it enters the nozzle chamber where the pressure in the pot forces it into the air
stream. There it is atomized and delivered to the work piece.
With a longer fluid path there is more
cleaning to be done with these guns.
fluid enters
here
Air to pressurize the pot enters here
Longer fluid pathway makes pressure pot
guns a bit harder to clean
The pressure pot guns are also easy to
clean, just not as easy as the gravity feed
guns. From the picture above you can
see that the fluid is contained in the cup
below the gun and the cup is pressurized
by the incoming air stream. In the case
of this Asturo gun the pressure tube leads
from a pressure controller screwed to the
inlet port on the end of the handle.
In both the Accurspray and the Apollo
turbine guns, pot pressure is taken from a
port on the side of the gun itself, a more
convenient location than the add on used
by Asturo, although the Asturo system
You first remove the air hose and then
remove the pressure pot and empty its
contents back into the finish material container. Next you rinse the pot well. To
clear the material out of the pickup tube
and the nozzle chamber you can refill the
pot with water, reconnect the air hose and
spray the water through the chamber until
all the finish material is rinsed out.
You can also remove the air cap and
nozzle, invert the gun under a faucet with
the pickup tube aligned with the water
coming out of the faucet and that will
usually flow enough water to flush out the
nozzle chamber. Often a brush will be
required to really clean the inside of the
pick up tube.
So, while the pressure pot guns are not
hard to clean, they do take longer to
clean than the gravity feed guns.
Comments about each gun
In the rest of this chapter I will record my
notes on each gun in terms of several criteria. The comments do not lend themselves to an easy table presentation, so
just follow along with the narrative to get
more detail on my impressions of each.
Accuspray Turbine Pressure Pot
Gun.
As I said earlier, I have owned this system longer and used it far more than the
others so I was surprised when it turned
up at the bottom of my subjective ratings.
The Accuspray and Fuji turbines can be
in the same room with you while you
work. The same cannot be said about
the Apollo unit as it emits a high frequency whine that is really annoying up
close.
For me, the Accuspray gun did not quite
lay down as nice a finish as the other
guns and is not quite as convenient to
use or to clean, both of which moved it
down in my rankings. It also looks a bit
older in design to me if that means anything.
The pot is pressurized via a port in the
side of the handle where the pressure
tube is well out of the way. This is the
only one of the pressure pot guns that
uses a screw-on rather than cam action
attachment of the cup to the gun. It has
worked well over the years, never leaked
and is easy to unscrew. It just takes a bit
longer than the cam action attachments
on the other two PP guns.
Even when attached to the four stage
turbine it does not seem to deliver as
much air at the air cap as the Apollo gun
does, at least with the factory recommended #5 air cap.
At the same time, I guess I was not surprised to see it finish higher in the rankings by the focus group members. I have
used this system with great success and
been pleased with its performance so my
guess is the focus group members saw
the same virtues that drew me to this system in the first place. It is much quieter
than the Apollo turbine and about the
same or perhaps even a bit quieter than
the Fuji three stage turbine as well. That,
and the nice packaging will make it an
appealing choice for many.
Change to the #7 air cap and that difference subjectively goes away. The finish
quality also improves noticeably. If I had
been testing this gun with the #7 air cap
instead of the factory recommended #5
air cap, it would have scored higher. The
focus group used it with the #7 air cap
and that might well explain the difference
in how they ranked it vs. my rankings
which were with the #5 air cap.
I found the fan a bit harder to control than
with the Asturo guns or with the Apollo
gun. It does offer continuous control from
conical fan to flat fan, but it took more fiddling on my part to get the fan I was after.
As stated earlier, the fan is much better
with the #7 air cap than with the #5. The
fan pattern with either of these air caps
seems wetter on the outer edges and a
bit thin in the middle to me. I found this
confirmed in the shooting tests as I
tended to puddle more at the overlap with
this gun than with the others.
I would like to have had a four stage Accuspray turbine to use with this gun as I
think that would have made a big difference.
Asturo Pressure Pot HVLP Gun.
This was not the case with one focus
group member who commented that for
him it produced the most even spray pattern of all the guns.
I did not find the trigger to be as linear as
with the other guns. There is less material flow at the beginning of the trigger
movement than towards the end. It is not
hard to control at all, just different.
This gun is a bit easier to clean than the
Apollo gun simply because the supplied
nozzle wrench is easier and faster to
mate to the nozzle. With this gun I found
myself removing the nozzle with every
cleaning. With the Apollo I didn!t remove
the nozzle as often.
Over all I can see why I have liked this
gun for as long as I have used it since
with practice it is capable of delivering a
very nice finish. It also seems to me to
leave the least over spray of all the guns,
but that is really hard to measure.
I think it suffers mostly from the factory
recommended #5 instead of a #7 air cap
and likely also a lack of air coming from
its three stage turbine as opposed to the
Apollo!s four stage turbine so it seems to
me to be more sensitive to viscosity than
the other guns.
I had a hard time warming up to this gun.
I found the add on pot pressure contraption awkward even though it does allow
individual control over pressure in the pot.
I suppose there is an advantage to being
able to control the amount of pot pressure
which you can do with this gun but not
with either of the other two PP guns, but I
was not able to really explore this in
these tests.
As a side note, the pressure pot and lid
supplied with this gun (shown above)
simply would not seal properly no matter
what I tried. I!m sure this is an issue with
this particular pot and lid and not with the
design. To make these tests I had to install the cup and lid off of the Apollo gun
on the Asturo HVLP gun.
With a properly sealing pot and lid attached, the performance was very good,
a bit ahead of the Accuspray and a bit
behind the others. I thought it should
have been identical with the Asturo gravity feed HVLP gun since they both use
the same air cap, needle and nozzle sets,
but I just did not think it laid quite as
smooth a finish. Maybe more fiddling
with the pot pressure would have improved things a bit.
Not surprisingly the fan pattern and ease
of control is the same as the gravity feed
HVLP gun. The trigger is just as linear
and easy to control as well.
Cleaning is on a par with
the other PP guns, a bit
more difficult than with
the gravity feed guns.
Asturo Gravity Feed
HVLP Gun.
This one I liked a lot.
Like all the Asturo guns
it is finished like a fine
watch or a nice piece of
metal sculpture. It just
feels so good in your
hands. It is light,
smooth in all its functions, and the ergonomics really work for my
hands. The air fan control and the fluid material flow control knobs
are easy to turn and
stay where you put
them. Like the other As-
turo guns, they have convenient markings
so you can make fine adjustments even
while you spray.
The trigger is very linear and has a light
feel that is not tiring to your hands and
the finish it leaves is really nice. I judged
the Asturo HTE and the Apollo to leave
an even better finish, but, if I had not
been working with them side by side, I
would be hard pressed to call a clear
“winner” in this regard.
I said earlier in this chapter just how easy
the gravity feed guns are to clean, and
I!m sure that biases my opinion in terms
of all the other aspects I like about this
gun. Everything is well made, well machined, and there are no sharp edges or
other perturbances to interfere with a
really nice user experience.
The conversion
guns did not appear to use a
great deal of air.
My compressor
is only a standard four HP
220 volt cast
iron single stage
unit with a 20
gallon horizontal
tank. It cycled
on and off in use
a bit but nothing
excessive. I
think I could use
these conversion guns all
day long and not
over tax this
small compressor.
Rated out put on
this compressor is 11.6 cfm at 40 psi and
9.3 cfm at 90 psi. The unit is several
years old so I don!t know how closely it
performs to those specs now, but it had
no problem keeping up with any of the
three conversion guns.
If you are thinking of buying a compressor to drive an HVLP conversion gun, I
would not recommend any of the pancake or small tank units designed for
powering air guns. I think they would cycle way too often and could leave you
starved for air if you were doing a lot of
spraying.
I also have reservations about the oil-less
units in this kind of an application
for much the same reasons. As
we discussed earlier, an adequate
supply of air at the air cap is all
important to good finishes with
HVLP equipment and you don!t
want your compressor to be the
weak link if you elect to go the
conversion gun route.
to be walking back and forth to the turbine to turn it on and off.
The four stage turbine puts out a lot of air,
palpably more than the three stage Accuspray unit. It is a stainless steel unit
with two large external filters (one front,
shown, and another just like it on the
back) that are easily serviced. Spraying
water based materials results in lots of
fine white powdery dust since what over
spray there is dries so quickly that it simply falls to the floor as this fine dust. So,
ease of cleaning the incoming air filters is
a significant feature and the Apollo approach is very good indeed.
Apollo Turbine Pressure Pot
Gun.
If there was a big surprise for me
in these tests, it was the performance of this four stage Apollo turbine and gun. I was immediately
put off a bit by the fact that is is a
bleeder gun - that is, air passes
through the air cap all the time
whether you are spraying material
or not. That seemed to me to signal an older or less sophisticated
design. But, that was not the case at all.
The bleeder issue was a non-issue. The
remote start-stop I added meant that I
seldom had air blowing when I didn!t want
it. It might be more of an issue if you had
The trade off is, this sucker is loud.
Where a compressor emits a low frequency pounding sound, this Apollo turbine emits a high frequency whine that
would be hard to live with if it was in the
same room where you were spraying.
The good news is they provide a long air
hose with nice machined brass quick disconnects that let you put the turbine in
another room, pass the hose through a
hole in the wall, and keep the most damaging and annoying high frequency
sounds away from your ears.
If you can!t get the turbine out of where
you intend to spray, plan on using ear
plugs.
The Accuspray and Fuji units are in an
acoustically designed case that seems to
do a good job of trapping the turbine
whine. The Accuspray unit is on wheels
for ease of moving it about and has on
board storage for the extra nozzles, needle tips and air caps. The Fuji unit, like
the Apollo, requires you to pick it up by a
top handle in order to move it about.
esses. All of the fittings are machined
brass inserts that fit well, feel silky
smooth, and perform exceptionally well.
The lack of a full fan control seemed at
first to be a drawback. In use, it did not
matter. Remember that the Apollo gun
changes from either a conical fan to a flat
fan by turning the air cap. There is no in
between, but I did not encounter any occasion where I wanted or needed more
fan shape control than I could get with
this gun. The fan size control is really
good - nice and linear, and the fan itself
seemed to be exceptionally smooth and
even all the way across. Additionally, it
seems to be a soft fan that transfers most
of the material to the work piece.
In my finish room I have a compressor
locker at one end. It is a closet-like structure that houses various compressors
and was ideal for also housing the Apollo
four stage turbine unit. Once in there, the
noise was no longer an issue.
The finish result is first rate, well ahead of
all the others in my testing except perhaps the Asturo HTE gun with which I
would rate it a tie or maybe just a bit behind. All of the materials flowed out
evenly and well coming off of this gun. If
this were a gravity feed gun I would be
hard pressed to call a favorite relative to
the Asturo HTE.
If you plan to work at a site with these
turbine units where other people might be
around, I would recommend looking
strongly at the Accuspray four stage turbine, the Fuji Quiet turbine, or one of the
other sound shielded units for their superior sound suppression features.
But, it is a pressure pot gun and clean up,
while simple, is not as fast and easy as
with the gravity feed guns. The small and
flexible air hose supplied with the Apollo
gun makes it easy to maneuver and handle. I like it better than the larger, bulkier
hose used by Accuspray.
Now, for all this talk about the turbine, lets
look at the Apollo gun itself and why it
scored so highly in these subjective ratings both in my rankings and in those of
the focus group.
Asturo Gravity Feed HTE Gun
First, it is a beautifully designed, cast and
machined item. The aluminum alloy castings are smooth and the obvious result of
quality molds and pressure molding proc-
Pictured on the next page, this proved to
be my favorite. While it appears to leave
noticeably more over spray in the air than
the other guns, strangely it also seems to
use less material. I can!t explain this in
any way other than the fact that the
rounder, softer, very even fan created by
have made it more difficult to maneuver
than the Apollo turbine gun with its equal
finish quality, but that just didn!t seem to
be the case.
This gun is not technically an HVLP gun
in that is uses more than 10 psi at the air
cap to work its magic. So, if you are in a
situation where you must have HVLP for
regulatory or other reasons then reach for
the Apollo or the Asturo gravity feed
HVLP gun.
If you donʼt have to have true HVLP
and already have a compressor,
reach for Asturo HTE gun. No
compressor or need portability?
Go with the turbine units.
Asturo HTE gun
this gun may well do a better job of atomizing the finish material in the first place.
As soft as it is, it just may hit the surface
of the work piece with less thrust but lose
a bit more of the very fine atomized particles in the air along the way.
Like the other Asturo guns this one is a
piece off art in your hands. It is light, responsive, easy to adjust, easy to maneuver, and just simply easy to like. Add to
these visceral issues the fact that it tied
for the best finish and is the easiest to
clean and it becomes the winner in this
comparison, at least for me. However,
you need to keep in mind that the focus
group ranked this gun much lower than I
did.
During these test sequences I built and
finished several pieces of furniture for clients. I most often found myself reaching
for the Asturo HTE gun to do so. I have it
hooked to a large air hose which should
Performance of the Finish Materials Themselves
ions of the focus group participants,
which material was used with which gun.
In this manual we have only looked at
certain Target Coatings finish materials.
We covered the characteristics of the
1000 series ultima spray lacquers, the
3000 series shellac sealer, the EmTech
8000 series conversion varnish, and the
9000 and 9300 series urethanes in an
earlier chapter.
With proper technique and fresh material,
right off of the gun the surfaces are
smooth and clear. The only blemishes
are from dust that might have settled on
the still wet surface. Those come off easily with a light sanding with the Abralon
material we will cover in the next chapter,
or with the use of soft (white) scrubbing
pads like those sold by 3M and others.
There are several materials which we did
not cover such as the 7500 series brushing varnishes or the 7000 series hybrid
varnishes or the EM6000 series production lacquers as I think most small furniture makers would find the ones we did
cover more suitable for their use.
In the finish room there were no surprises. No matter which material you select, prep the work piece as described
earlier, use the spray system and gun you
like the best, and you will get an outstanding finish result, likely better than
any finish you have obtained in the past.
When I started these tests I expected this
chapter to one of the longest in this manual because I expected interaction effects, that is, I thought some finishes
would lay down better with some guns
than others. That proved not to be the
case.
I already had enough experience with water based materials to know that there are
not great differences in appearance, one
material over another, so that was not a
surprise. What differences there are I will
cover in a moment.
But, back to the lack of gun/material interaction effects. It did not seem to matter either to me, or to the collective opin-
No matter which of these HVLP or HTE
guns you select, you will not be disappointed in the finish with any of these materials. Choose the materials based on
what you are trying to achieve and enjoy
all the many benefits from water based
finish materials.
In terms of appearance, in general the
conversion varnish produces the softest
looking finish to my eye. It flows out
really well and bridges a bit better than
the others. This is a handsome finish for
most applications. It does not burn in between coats the way the Oxford Ultima
lacquer will so you do need to be careful
not to sand through the previous coat,
especially along the edges.
The varnish is half again as expensive as
the lacquer so I like to combine the two
as was discussed earlier.
The lacquer is the all-around finish of first
choice for me for most applications. It is
the least expensive of the materials we
covered and it gives first rate results in
nearly every application. It has a very
clear presence on the wood and is very
forgiving to use. In low glosses it looks a
bit like non-build oil and wax style finishes. yet in higher glosses it can be
buffed and polished to great effect.
The Ultraseal-WB Shellac Sealer and
Barrier Coating is the problem solver. It
brings out the grain in darker woods and
prevents blotching in really soft woods. It
is the universal barrier coat to separate
whatever you need to separate from the
other water based finishes. In the blonde
color it doesn!t amber lighter colored
woods as much as alcohol based shellacs tend to do, and it is 100% wax free.
The two urethanes are best on surfaces
where you want the ultimate buffed and
polished look (think grand piano or high
end guitar). We talked earlier about how
they are very abrasion resistant and also
stick tenaciously to well prepared surfaces that might be exposed to shrinking
and swelling. From an appearance stand
point they look much like the other finishes in the flatter sheens but can take on
a more artificial or plastic look unpolished
in the higher glosses, at least to my eye.
Polish them after they cure and the results will knock your sox off.
My usage recommendations are:
1) use the shellac for a barrier coat,
not a final finish.
2) use the sanding sealer to raise
the grain and prep the wood for
your build and top coats on most
every project.
3) use the lacquer for your every
day finish work for its coat-to-coat
burn in characteristics. It works
especially well for vertical and inside surfaces for most interior projects, and on horizontal surfaces
that are not expected to be sub-
jected to water, household chemicals or heavy abrasion.
4) use the conversion varnish for
most horizontal surface applications and for anything that will be
exposed to UV, water, or chemicals,
and for all your exterior projects.
5) use the urethanes for high wear
surfaces or where you want to buff
and polish to an extremely high
gloss.
6) no matter which material you select, use gloss only as a build coat
where you intend to top coat with
satin or flat, or where you intend to
buff and polish the surface to a
high shine.
This is a personal bias as I just do not like
the gloss look by itself for fine furniture. It
somehow looks artificial to me. Buff and
polish it and it becomes one of my favorite finishes no matter which material you
use. More on that in the last chapter.
Finish Problems and What To Do
About Them
of post-shoot sanding, buffing, and polishing work to get rid of them.
There are only a few finish problems that
you are likely to encounter. These will be
fisheyes or craters in the surface, or peeling of the surface especially along an
edge, or a milkiness or blushing on
darker woods, or a dry grainy look to the
surface.
2) The work piece was contaminated with
oil or stearates from use of the wrong
sand paper. Oil and water just don!t normally mix well.
If you do encounter finish problems, suspect either contamination of the wood
surface, out of date material, or something really wrong with your technique - or
that you foolishly tried to overly “thin”
these materials with water.
If you see craters or fish eyes then
one of three things likely happened:
1) The finish material you used was nearing the end of its shelf life. These materials all have a definite shelf life. Target
Coatings can tell you the expected shelf
life for each. I recommend you date a
can when you buy it and date it again
when you first open it.
I!m not sure technically what happens at
the end of shelf life, but it seems to me
that most of these materials eventually
begin to form coagulant particles that spit
out the gun, land on the surface a bit like
fine grit and then force the liquid material
to flow around them leaving craters or
fisheyes. If you are nearing the end of
the shelf life with a can of material, spray
a test panel and examine the results before you spray your just completed piece
of furniture. If the test panel shows craters or fish eyes, toss the material as it
has likely exceeded its shelf life.
If you insist on shooting it anyway (we all
are overly frugal, right?), then plan on lots
There are ways of producing oil disbursed in a water based material the way
Target does with its line of Ultima-WR
Stains, what they call “a water-reducible
linseed oil stain system.” But, other than
that, if you have oil on your work piece,
neither the EM 8800 Universal Sealer nor
any of the other top coat products will adhere very well to those oily spots. If the
oil is dry you may be able to top coat it
with the water based shellac sealer and
barrier coat, but always run tests first to
see if it will seal well enough to allow the
top coats to adhere properly.
Sometimes you can let the coat dry for an
hour or more and then wipe the surface
with a clean cloth wetted with lacquer
thinner or acetone. Don!t let these stand
on the surface for very long, just use
them to try to remove the contaminants.
Sometimes this works and sometimes it
doesn!t, but it is worth a try.
The best bet is to get rid of these contaminants before you lay down the water
based finish in the first place.
3) You sprayed the material on too thick
or recoated too quickly. All of the water
based materials need time to fully flow
out.
The surface tension in these materials
seems to me to be greater than for oil
based finishes. As a result, the water
based materials will tend to flow around
grain pores and other surface imperfections rather than bridging over them the
way their volatile organic based cousins
do.
If you spray on too thick a coat, especially
with the early coats where the material
flows around the cell openings in the
wood surface, it can leave a build up on
the perimeter which looks a bit like a crater. Sanding between coats can minimize
this effect.
The more damaging issue from too wet a
coat is that the material may dry unevenly
top to bottom resulting in wrinkles or
ridges. These are harder to sand out.
My experience is you are better off to put
on too little per coat than too much. As
your skill increases you will learn when
and by how much to increase the thickness of each coat. In the beginning “less
is more” is a good mantra.
If the finish peels up or flakes off then
one of three things likely happened:
1) The surface was contaminated with oil
or stearates from use of the wrong sand
paper. Just as we discussed above you
either need to clear the contaminate or
seal it with the shellac barrier coat if you
can.
2) You recoated too quickly. If the previous coat is not dry enough, especially on
very resinous woods, re-coating too soon
can cause adhesion problems.
3) You really did not thin out this stuff with
a bunch of water, did you? Water will
work as a viable “thinner” for some, but
not all, of these materials. Some water
can be added if it is pure and not contaminated with a bunch of other stuff, but
too much is really “too much”. Ask before
you over thin!
Knowing what happened is easier than
figuring out what to do about it when it
comes to adhesion problems. Seldom
can you just clean up one bad area and
re-shoot that spot with success. In most
cases you will need to sand the whole
panel down to bare wood and start the
finish process all over again. If you used
the lacquer, you have a chance of doing a
spot repair since it will burn in. If you
used one of the urethanes or the conversion varnish, you almost never can do a
successful spot repair.
If the finish looks milky or blushed
don!t worry, that condition will most always go away within a few hours to a few
days. This usually occurs when the coats
were a bit too wet or recoated a bit too
soon, or both. It occurs mostly on darker
woods. A barrier coat of the water based
shellac does wonders for bringing out the
grain and minimizing this effect on dark
colored woods.
If the finish looks grainy or leathery
rather than really smooth, it is most likely
because you held the gun too far away
from the surface of the work piece. If you
are too far away, the water based materials will tend to dry a bit before they are
deposited on the surface. This prevents
the material from flowing out the way it
should and can leave the surface looking
grainy or with a rough leather like surface.
I noticed this with all the focus group participants and other “first timers.” They all
start out holding the gun either too high or
at an angle which means one side of the
fan pattern must travel longer to hit the
work surface than the other. Either one
of these technique problems can cause
the grainy or rough surface. Sand it flat
and reshoot. It is that simple to correct.
The Final Finishing Steps
Most of the time the finish you obtain with
these Target Coatings water based finishes right off of the gun will be outstanding for most parts of your piece. The very
visible horizontal surfaces like table or
chest tops usually warrant additional attention, however, as those are surfaces
most often admired by your customers or
friends.
With any water based finish be careful
not to try to flatten the final surface too
much or you will begin to bring out a
gloss you may not want. This surface
gloss occurs as a result of the light reflecting off of the smooth surface rather
than being refracted by the flattening
agents mixed into the material to produce
the semi-gloss, satin or flat sheens.
The more the light is refracted, the lower
the gloss appears to be. The more it is
reflected off of the surface, the higher the
gloss appears to be.
One good way to take off any dust or
other minor surface irregularities is
through the judicious use of a mesh material into which have been imbedded silicon carbide and other man made abrasives. These mesh like materials often
are adhered to a foam backing material to
allow them to massage the surface without gouging.
One of the well know brands is a Mirka
product called “Abralon”. I use them from
500 up to 4000 grit. Most often I use
them in 6” (150 mm) round pads that stick
to the hook and loop backing on my random orbit and dual mode sanders.
Use a light touch, slow down the speed if
your sander has variable speed, and
keep the sander moving. You are not trying to remove material from your finish,
only to take off and dust or other spots
that leave it less than perfect.
Start with the finest (highest number)
Abralon pad you have and see if it removes these dust spots. If not, move to
the next courser pad and see if it removes them. Once you find a grit that
takes these dust spots off, then progress
to the next finer grit. Be mindful of the
gloss you are building up. You can
quickly take a satin or flat finish to a
higher gloss than you may want.
If you do get too much gloss for the look
you are after, you can soften it by using
the next courser Abralon pad, or by rubbing it with fine steel wool, or by applying
a wax like Briwax. While the wax imparts
a shine, it is a soft shine that most associate with a desirable patina so they don!t
think of the surface as “shiny” only “silky.”
Never use steel wool between coats with
water based finishes. Microscopic particles of steel left behind will rust under the
surface creating marks that cannot be
removed. On darker woods they are
harder to spot, but on light colored woods
they will raise havoc with an otherwise
perfect finish. It is OK to use the steel
wool after the final coat has cured and, in
the right hands, steel wool can impart a
beautifully soft flat surface. Just be mindful that the steel wool is adding very fine
scratches that cause light to refract rather
than reflect off of the surface rendering
the flatter look. If you over do it the surface simply looks scratched.
Another “trick” with the Abralon pads is to
burnish raw wood. Sand up through the
finest grit you have in sand paper and
then progress up through the finest grit
you have in Abralon. If the
wood has much natural resin,
you will be amazed at the
deep patina you can achieve.
Of course, this burnished raw
wood has no protection so that
patina will be short lived if it is
touched, but the effect is stunning. If you do want to protect
it a bit, just use wax. Use
three coats of a quality wax
like Briwax and the patina will
remain so long as the piece is
not handled much.
Remember those loft kitchen
counters we saw earlier?
Well, here is a picture of the
hood vent over the commercial range in that same kitchen
getting its treatment of just
Abralon and Briwax applied to
the raw wood.
In this case I was trying to impart an old look to the South
African Bloodwood that faced
the vent hood all the way up to
a 14! high ceiling as a foil for the very
modern look and design of the cherry and
blood wood kitchen cabinets and counter
tops.
You can see the “old world” patina and
sheen that was developed with just Abralon pads and Briwax.
On the other hand, if what you want is
that incredible deep mirror like gloss of a
grand piano or high end guitar, it is far
easier to do than you might imagine.
These water based finishes are perfect
surfaces to buff and polish. These products are similar in many respects to the
clear coat on a modern automobile so the
same buffing and polishing compounds
used on the car finish work just as well
here also.
You can use any brand but the one I particularly like is made by a family owned
German company called, “Menzerna.” It
is the largest supplier of polishes and
compounds to Germany's automakers
and is considered by many to be a world
leader in abrasive and polishing technology.
Start by letting your finish cure for several
days - a couple of weeks is even better,
especially with the urethanes. Then,
sand the finish perfectly flat with 400 grit
paper. You do not want to sand through
the finish, only to take out all of the surface irregularities. You want an even dull
look to the surface much like one seeks
while “color sanding” or “block sanding” a
car finish.
Once the surface is nice and flat and
evenly dull, you can start the buffing and
polishing process.
piece in one of the earlier photographs.
In this sequence we will see it go from
raw finish to a “jaw dropper” even though
it is just a test panel.
In the photographs you can see the burl
piece from which the burl inlay was cut. I
put a clean felt pad on the buffer, then
used a stick to evenly spread the first of
three rubbing compounds we will use
(photo left). All three and the final finish
polish are shown on the table.
This one is the Menzerna DD3 Course
Compound. It is very aggressive so you
want to use a light touch and a slow
speed. A little bit of compound evenly
spread on your pad will go a long way.
Applying Menzerna DD3 course compound across the face of the felt pad
with a stick. A little goes a long way
so don!t put on too much.
The compound does all of its work just as
the compound begins to dry out so initially all you are doing is spreading the
compound evenly across the surface of
the work piece.
As the compound begins to dry out the
gloss will build very quickly. Lighten up
I use my Festool RO150 dual mode
sander with the rotary mode selected. It
is really a rotary mode with a simultaneously rotating pivot point so the pad
moves in a complex pattern a bit like the
child!s toy called a “spirograph” from
years ago. I replace the backing pad with
one specially designed for felt pads and
sheepskin bonnets.
You can use any rotary buffer you wish as
long as you can slow down the speed so
as not to burn the finish with the rubbing
compounds.
For this example I made up a test panel
of Brazilian Cherry with inlays of both
Maple Burl and Blood wood. We saw this
Lightly run the buffer over the surface of the work piece to distribute
the compound evenly. As the
compound begins to dry out
lighten up on your touch.
even more and don!t try to over work the
surface. You have two more compounds
to go to get the really deep gloss. Just
use this one to take the even dullness left
from your sanding to an even shine.
If you over work the piece at this point
you risk burning the surface of the finish.
You won!t believe how fast you can build
up heat with a compound like this. If you
do burn the finish there is not much room
for recovery. So, easy does it. Let the
materials do the work for you.
Use a rag to wipe off any remaining compound.
Now, remove that felt pad and set it
aside. Mount a new or clean felt pad to
receive the next grit in the sequence.
This one is called Menzerna 2L Paste.
are just lightly touching the surface and
let this grit bring up the deep gloss.
The photo below left shows the gloss
from just the first two grits. Notice that
the gloss is even across both woods and
the burl.
In this case the sample piece was finished with one coat of EM 8800 sealer
and sanded up to 400. Then 2 coats of
1028 gloss lacquer were applied and the
piece sanded again with 220 followed by
400. Then two top coats of 1028 gloss
lacquer were applied and left to dry over
night. The next day the piece was
sanded flat with 400 and then again with
800 before the buffing you see here began.
It is now time for the final buffing compound, this one called Menzerna 16
Do the same thing as before - use a stick
to spread it evenly over the surface of the
felt pad. Then, with the buffer still set to a
slow speed, evenly spread this grit over
the work piece.
Again, use a light touch and let the grit
begin to just dry out. At this point a really
bright shine (photo above) will develop on
the surface. Lift up on the buffer so you
The final gloss is jaw dropping!
Paste. Add a new or clean pad and
spread the 16 paste lightly over the pad
surface.
Work the buffer just as before with a light
touch evenly disbursing the material
across the surface, then wait for the
compound to just begin to dry out. Lift
weight off of the pad so the drying compound can work it!s magic. Sit back and
admire the final result - a beautiful deep
glass like shine across all three woods.
thinking of it as a chore to be avoided. It
will become the culmination of the creative process that drew you into woodworking in the first place.
Enjoy!
The whole buffing process took less than
ten minutes and I never did use the fourth
step, what is called the “Menzerna Intensive Polish. It is a very white color and
sometimes a bit of residual white can become imbedded in the grain imperfections when I elect not to do a complete fill
or “tight” finish as on this piece.
If the finish calls for a complete fill, meaning none of the grain shows in the gloss
at all, then I use the Intensive Polish to
bring out the last bit of deep gloss.
Conclusion
In this manual our objective was to explore ways you can improve the quality of
your woodworking finishes without subjecting yourself or the environment to the
assault from the volatile organic compounds present in most conventional finish products. Once you learn to use water based finish materials and apply them
with High Volume Low Pressure spray
equipment I doubt if you ever go back to
those smelly volatile organics or messy
wipe on stuff.
More importantly, I think you will not only
wind up with a superior finish on your
work, you will actually look forward to the
finish process with anticipation instead of
Jerry Work designs and hand crafts fine furniture in the 1907 Masonic Temple building in
historic Kerby, OR
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