"The Rule of Threes"
Applying Solid Colors, Metallics and Blonde
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preparation may be the single most important element in obtaining a professional
mirror like final finish and also the phase of finishing often most casually
approached. Raw wood doesn't always reveal it's secrets. In fact without
careful inspection during the preparation stage many misdeeds will not
be evident until the final clear coating.
the wood has been stripped inspect the wood to locate any problems which
may become offensive. Search for such things as very deep sanding scratches,
cross grain sanding or dents in the wood. Be especially diligent in searching
the areas where cross grain sanding may have most likely occurred such
as the area behind the bridge on an arch top or at the heel of the neck.
Scratches which may be nearly invisible will become evident when dye is
applied. The dye will stain the exposed end grain in the scratch and darken
it. If you find a sanding scratch after the dye has been applied the dye
(and the scratch) will have to be sanded out and restained.
dents are most common on the back but don't overlook the peghead sides
and ends and the area around the jack. If the dents are very deep they
can be filled with a colored wood filler and sanded flat. A fine point
graining pencil can be used to draw in grain lines if needed. Now is also
the time to try and locate any low spots caused by careless (read blockless)
sanding. Although barely perceptible now these swales will look like deep
rounded valleys after the final polishing. Most sanding swales can be sanded
flat with a sanding block. Deep swales can be cured with repeated fills
of a clear nitrocellulose sand and sealer such as Parks.
other problem should also be noted. Sometimes when chemically stripping
the old finish will melt and act as a dye. Black paint is the worst followed
by red. If the plan is to recolor with the same color as the color that
was removed there should no problem. But if a different color or natural
finish is desired and the old color still partially remains bleaching may
my experience colors can be removed with two or three applications of chlorine
laundry bleach. Some color may remain in the grain but usually not enough
to affect the final finish. Water marks can be removed with oxalic acid
crystals. Most hardware stores carry this type of bleach.
the wood clean and sanded. The finish prep can be begun. The steps given
may or may not be needed with a particular wood. The steps following will
assume the wood being finished is a "worst case" wood, i.e.; mahogany.
Rosewood, ash and walnut also fall into this category. (Note that "worst
case" woods are not really that. The oily woods such as paduak are the
real worst cases.)
first step is to wipe down the wood with naphtha. This will remove any
oils that may have gotten on the wood during handling. When dry the wood
should be filled with a grain filler. My personal choice is an oil based
grain filler. I am sure that water based fillers can work equally well.
Grain fillers are available at all good wood working stores and some hardware
stores. When working with a colored filler it is best to seal the wood
with one or two coats of lacquer to prevent the stain in the filler from
staining the "field" area of the wood. It is best to let the sealing lacquer
dry overnight so that it dries into the grain and does not displace the
filler can be wiped on with a cloth although I favor using my fingers.
When slightly dry (dry enough that wiping does not pull the filler from
the grain) the excess can be wiped off with a rough cloth. If you are careful
it can be gently scrapped off with a single edged razor. In either case
wipe or scrape across the grain. The razor method seems to pack the excess
filler into the grain and is why I prefer it. Remove as much as you can
now while the filler is slightly wet and you will reduce the time needed
in the later sanding step.
dry (overnight) the wood can be sanded clean. Time can be saved before
by using a rag damped with mineral spirits to remove the majority of excess
grain filler. If you decide to wipe off the excess filler let the filler
dry again for a few hours before sanding. Using #180 dry sand off all of
the filler in the field of the wood. Be sure to get the filler that is
in the neck to body joint, in the switch holes and over the edge and in
the pickup and control cavities. Filler in the screw holes does not hurt
and may even help in that the filler keeps water out of the holes when
doing the final wet sanding. (Water in the screw holes may cause the wood
to swell and result in lacquer chipping around the screw holes). When sanding
always go with the grain of the wood to prevent scratches. Follow with
#220 dry sanding.
sanding clean I suggest (and religiously use) a second filler treatment
to achieve an ultimately glass like finish. First the reasoning. The glass
like finish of a nitrocellulose finished guitar comes from the multiple
application of lacquer and removal by wet sanding. And although the desired
finish can be obtained by multiple lacquer coating only, there are two
problems which at their base are both time related. The first problem is
that multiple coatings (something in the 20 to 30 coat range) and sanding
flat after every few coats is in it's self very time consuming. And secondly
nitrocellulose, while drying to touch and a practical use level very quickly,
it continues to dry over months and perhaps even years. A finish that appears
mirror flat when applied will continue to dry and if the grain was not
filled totally flat, in a few weeks, the grain may begin to show as the
lacquer continues to "dry in".
the wood has been filled spray with one or two coats of lacquer to lock
in the filler and color. To achieve a mirror finish relatively quickly
(and one that will remain stable as the final lacquer coats dry) next apply
a high solid content sand and sealer product. Parks Corporation makes a
nitrocellulose product which fills this requirement nicely. The application
is simple as the sealer can be brushed on. Brush on the first coat and
allow to dry for a few minutes. When the surface is flat (non reflective)
a second coat can be brushed on. Allow this double coat to dry at least
an hour (I usually wait overnight). When dry the coats can be block sanded
flat. I suggest that this sanding be done in an area where dust is not
a concern. You will see why when you begin sanding. I also suggest that
you wear a mask. When this two coat application has been sanded flat (no
shiny spots) wipe down with a dry cloth, inspect again for shiny spots
and repeat. That is; apply two more coats. Paint them on as before with
time allowed between coats for the coats to dry flat. When dry (again at
least an hour) sand the coats flat. During sanding wipe off the dust to
aid in locating pits which will appear shiny. The base you are creating
will be the foundation for the lacquer finishing coats. Unless corrected,
any pits, runs or unfilled areas will show in the final lacquer coats.
Because of the high solid content of the filler, corrections can be made
much easier at this stage.
base should appear flat with no pits showing. If you find pits they can
be drop filled with the sand and sealer and sanded flat. You will find
that pits and swales that are too deep to be safely sanded out can be made
invisible with repeated fills. Color coats and clear coating can now be
Spraying and the "Rule of Threes"
the solubility has been chosen the dye needs to be mixed. Mix to the suggested
formula or "to the eye". After mixing, allow the dye time to dissolve into
the chosen solution. It is recommended that the dye be allowed to dissolve
for about three hours after mixing. You may find that with water soluble
and alcohol soluble dyes the dye will not completely dissolve. These two
solubilitys seem to have a lower saturation point than does lacquer reducer
and dyes dissolved into these solubilitys may leave specks of undissolved
dye in the mixing container. After the dye has been dissolved it is suggested
that the solution be strained to remove any particulates. An old T shirt
can make a good strainer. Coffee strainers can also be used.
cautionary note is that dyes containing blends of black should not be finely
strained. Even when "completely" dissolved the black component particles
are larger than the other typical color particles. Straining can remove
the black component thereby lighting the color. With black dyes allow the
dye to dissolve, stir the solution, let it sit for about a minute then
decant the solution. Three decants should remove the heavier particles
without changing the intended final color. Another note is that you should
be aware that a dye mixed in alcohol will appear to be a slightly different
hue when mixed in lacquer reducer. This is due to the different solubilitys
of the two reducers.
refinishing the dyes can be either bulk mixed or batch mixed. Batch mixing
typically will use a ratio of 1/4 tsp.dye to 8oz. of reducer. Unless stated
otherwise, the applications discussed will use lacquer/alcohol dyes batch
mixed into lacquer reducer for spraying and batch mixed water based dyes
solution now requires one more step. If the dye is to be used to lightly
color the wood or tint another base color the dye solution can be added
to a 2 or 3 part reducer to 1 part lacquer solution and sprayed. An example
would be the spraying of the amber of a sunburst or the tinting of a previously
applied color coat.
dye is to be used as a medium dark to dark solid color or a dark shading
color then the dye solution should be thinned with reducer, a small amount
of lacquer and then sprayed. An example of this application would be the
spraying of the dark edge color of a sunburst. The goal is to apply enough
color to achieve the darkness required while not over applying lacquer.
A typical solution would be 1 part mixed dye solution to 6 parts reducer
with a cap of lacquer added to 8oz. of the mixture. The lacquer not only
gives body but it will also cause the black component of the dye to "lie
down". Also while wet, the lacquer will allow you a quick look at how the
coloring process is progressing.
should be done in an area with adequate ventilation but also in as clean
of an area as possible. Keeping the finish dust free during the spraying
process will make final finishing easier. Most spraying can be done with
the instrument in a hanging position. If it is difficult to spray certain
areas such as the bottom or in the areas inside the cutaways the instrument
can be laid flat. Suspend the body a couple of inches above the work
surface with blocks positioned in the control or pick up cavities. This
will make spraying the sides easier and prevent the lacquer from gluing
the body to the work surface. Before spraying wipe the body with a tack
cloth to pick up any stray dust particles.
first coats should be light. Two light spray passes followed by allowing
the lacquer to dry to touch and then three more light passes will give
a good base to build upon. Let the lacquer now dry at least three hours.
Remember to use the tack cloth after each "hard" drying period (three hours
or more). If the tack cloth is used before the lacquer is set you may transfer
dust to the finish rather than removing it.
drying check the surface for dust. If any large particles are apparent,
they can be wet sanded out with #600 paper. Be careful not to get into
the color coat. With larger particles you can often feel them "roll" as
they become sanded out. As always when sanding thin coats, wipe the area
dry often to check your progress. In this case checking every four or five
sanding strokes would be prudent.
perhaps now would be a good time to explain "coat" and "pass". A pass is
just that: i.e. one spray pass. A coat is a number of passes from 1 to
?. In the technique used to develop these pages, a coat is typically three
passes. Sometime two will sufficiently wet out a small area and sometimes
four will be used. Five approaches foolhardiness. Six will almost always
guarantee a run.
you are using a gun that is adjustable, a typical setting would be the
fan set wide enough to cover about 1/2 the area to be sprayed and air pressure
at 20 to 30 psi. Liquid feed is set to allow you to wet the area by slowing
down the guns movement. The setting should lean more to light. A wetter
spray setting may force you to move the gun faster to prevent runs. Control
the tool. Do not let it control you.
the first wet coat (after wiping with the tack cloth) make three passes
and stop. The surface will probably not appear very shiny as it dries to
touch. (If it does the coats may be too heavy). Now let this first coat
dry at least three hours. Tack cloth the finish and make three more passes.
As you proceed, wetter passes become safer to make so you may want to slow
down the guns movement as you spray. These passes will appear wetter as
the finish gets deeper. Let this coat dry at least three hours. For the
last coat of the day, tack cloth, spray three passes and let dry until
spraying the next coat, wet sand the finish to remove any runs or particles
that may have settled onto the finish. Start lightly with #400, #600 and
end with #800. Let the surface dry and repeat yesterdays schedule. I.e.,
three passes, let dry three hours then repeat and then repeat. Let to the
finish dry overnight and sand as you did the first day.
third days spraying is a "re-repeat". Summing up this spray technique,
spray three passes to make a coat, allow each coat to dry at least three
hours and spray no more than three coats a day for at least three days.
Hence, "The Rule of Threes".
allowing the instrument to dry at least three days (with nitrocellulose
lacquer, the longer the better) final sanding and polishing can be done.
The sanding will be done with successively finer grades of paper. The paper
found at automotive color supply stores works well. The grades required
are #400, #600, #800, #1000, #1200, #1500 and #2000. One sheet of each
is all that is required. Allow the paper to soak overnight in water before
a small flat block when sanding to prevent your fingers from causing furrows
in the finish. As noted a small computer battery is a personal favorite.
Sanding first with the #400 grade, sand until all the shiny spots are gone.
When done correctly, the finish should be uniform and matte. As you move
up to the next grade check the finish in a good light. You should find
that the finish is becoming more reflective and that the sanding scratches
are becoming fainter. At the #1200 level the finish is now being polished
and should reflect images. If you find you have missed a spot, sand backwards
until the grade is reached that will blend the spot and then move back
to the grade level where you were in successive grades.
caution when sanding to avoid sand throughs. Be especially cautious when
sanding at the edges of the body. The finish may be thinner there and the
difficulty of keeping the block flat when sanding over an edge can make
a sanding through more likely.
the final grade of sanding is completed, the final polishing can begin.
Use a soft cotton rag either folded or shaped into a ball and held between
the fingers. Either way try to prevent individual fingers from causing
furrows. Polish in random circles. The polishing can be done in steps starting
with a white polishing compound. If the surface was prepared as noted in
the last section, red (more abrasive than white) compound should not be
necessary. In fact white can probably be skipped and the finish can be
polished with a swirl remover type polish. We use the 3M product, "Finesse
It II" going directly from #2000 to final finish. Skipping the white and
red steps may take longer to polish but on a relatively new surface the
final polish seems more reflective.
instrument is now finished. Take more than normal care for the next month
or so when playing and handling. The lacquer is still relatively soft and
can scratch. The lacquer will continue to harden for literally years but
should reach its practical hardness in 30 to 60 days. Enjoy your work with
the best planned journey will sometimes have an unplanned detour. This
section will cover some of the more common "detours" that can occur with
a finishing project. They are presented in no particular order along with
possible causes and corrections.
is a whitish haze in the finish..."
haze is caused by "blushing". You will see it mainly on black but darker
reds show it sometimes as well. It is caused by moisture in the color or
clear coat. The moisture gets into the paint when the paint is sprayed
during periods of high humidity. Spraying during a rain shower, during
the cooler part of a moist day and spraying a very heavy coat on a warm
humid day increases the chances of blushing.
to do? If you see blushing, Stop. The moisture is trapped in the very top
coat of the finish. Take the body into a warm and dryer area and let it
dry. Lacquer allows water to move slowly through the finish and most times
the blushing will disappear as the finish dries. Blushing can also be removed
through sanding. It can also be removed by spraying the finish with straight
lacquer thinner. (Some finishers add a small amount of retarder to the
thinner). If the moisture is trapped deeply in the finish you made need
to use a product called "Blush Eraser". Blush Eraser reconstitutes the
lacquer to allow the moisture to escape. Behlen makes the most popular
eraser and provides it in an aerosol.
spraying the first few lacquer coats I've noticed hundreds of small pin
holes in the finish...."
holes can be caused by a number of factors. The most common are contamination
of the wood by wax or silicon (Armor All used on the case or plastic parts
can be a source of this type of contamination), temperature changes during
the spraying /drying cycle and moisture in the wood. Wood contamination
can be sanded out in most cases. Wiping with naphtha will also help in
removing contamination. Temperature can also play a role in the formation
of pinholes. If a guitar that has been in a cool environment then
sprayed (as might be the case if you are spraying in an unheated garage)
and after spraying moved into a warm environment to dry, air bubbles may
form as the wood warms and push their way through the lacquer leaving pinholes.
The last frequent cause (and probably most common) is moisture in the wood.
Water can get into the wood through washing stripper from the wood, wet
sanding primer or sealer coats or not allowing a water based filler or
water based dye enough time to dry.
solution? Sanding and wiping with naphtha should remove wood contamination
and not subjecting the wood to major temperature changes during the spraying
and drying process will prevent pin holes caused by bubbles (note that
placing newly finished wood in the sun to dry is a guaranteed way to cause
pin holes). Allowing the wood sufficient drying time after wetting will
most likely eliminate moisture related pin holes. A sure way to prevent
pin holes before spraying the lacquer coats is to seal the wood with a
clear sand and sealer on translucent finishes and sand and sealer and/or
a white pigmented shellac on opaque finishes. If you didn't seal the wood
and now have pinholes you may be able to drop fill them with unthinned
lacquer. The lacquer will over power the cause of the hole and allow subsequent
sprayed coats to flow over the holes. After spraying about two coats the
"bumps" from the filling can be sanded flat. Drop filling will work on
sectional pinholes but if the holes are numerous and over a large area,
starting over (this time either correcting the problem and/or sealing the
wood before spraying the lacquer) may be the best solution.
accidentally sanded through the clear and color coat into the primer coat...."
through is easy to do. It will most likely occur over the edges of the
body. If the sand through occurs during the color or clear building stage
you can simply respray the sanded through area and respray the color or
clear coat. Complete overspraying is usually not needed. If you sand
through into the wood you will need to refill the wood. For such a
sand through sand and sealer only can be used to seal the wood. The white
primer can also be used but may not be necessary. To prevent future
sand throughs use a block where you can and when beginning the wet sanding
use a finer grade paper (#800 to #1000) to get a feel for the process.
Once you are comfortable you can move down to #600 or #400 for faster sanding.
are some major belt buckle scratches on the back. How can I fill them...."
scratches can be filled with a good grade wood filler. Use a solvent base
filler if possible. Water based fillers sometimes swell and shrink under
lacquer. Bondo will also swell under lacquer. For medium depth scratches
such as buckle scratches if the scratch still is showing after the recommended
four coats of sand and sealer, drop fill just the scratch with clear sand
and sealer. Sand flat when dry.
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