I found a good article on painting a car so I thought I would share it. anyone with experience, please chime in and make any corrections, or give tips. I want to try to paint my own car, its something that I have always wanted to learn to do, so I am loking for as much information as possible. This article lacks painting techniques, so i would like to know some more about that if anyone can help explain.
Another in the fine How To series.
The first thing you must do is strip the car. Decide how much of the car
to take apart and how far you will go. The best paint jobs have all the
old paint removed and all moldings, trim, bumpers etc. removed. There is
no need to remove suspension, engine, interior or anything else as these
items are easily masked off. If you do the total restoration then you
would be stripping the whole car to the shell, but for just an external
paint job it is not necessary. Strip the car in what ever means you want.
Chemical strippers do a nice job, but require careful washing of the car to
remove all residue and they make a mess on the floor. Any small amount of
stripper left in some corner can ruin a paint job. And besides they are
smelly and burn the skin. Also, strippers will damage any plastic filler
so all filler must be removed and replaced. The alternative is to use
abrasives to strip the car. Using a 9 inch sander with 24 or 36 grit
paper, you sand until you see metal. If the paint job was an old lacquer
job or used lacquer primer, then a razor blade may be used to remove the
top layers. This method will remove some filler as you hit it so you must
be careful. Once you hit metal use an 80 grit to rough up the metal for
better paint adhesion no matter what stripping method you use. If filler
is over 10 years old, or from an unknown paint job, then it should be
removed and replaced. Either use the 9 inch random orbit sander or a
knotted wire brush on a 4-1/2 inch angle grinder. I prefer the wire brush.
There are some more exotic methods if paint removal if you have the
finances. Media blasting with Walnut shells or Dry ice pellets works well
but is not recommended unless you are doing a total strip of the car.
NEVER sand blast a car body. The sand acts as a peen (this is how they
shot peen rods) and will make body panels look like the ocean in a
hurricane. You can also acid dip the car which will remove all rust and
paint, but the car must be entirely stripped.
After you have the car stripped, then the metal work begins. Small dents
can be worked out by using a hammer and dolly or a semi pointed probe
worked across the metal on the back side. I worked out several small dents
this way and did not have to use any filler at all in those places. Larger
dents have to be banged out using the hammer and dolly the best as can be
done. Unless you are an artesian then you will have to use filler on large
dents. Be sure to not have any high places in the metal or you will have a
bump in the final paint finish that cannot be sanded down. Often high
areas can be “shrunk” by using a pick hammer with a dolly in the back side.
What you do is exchange the large dent or bump for a whole bunch of small
bumps that are easier to fill and cover. Lightly just tap over that rise
area working from the edges to the center and the bump will slowly
disappears. This may take some practice to get good at. If you drill
holes to pull out a dent, then you must weld up the holes when done to
prevent moisture from getting to the back side of the filler material
through the holes.
There is only one way to fix rust. Cut it out and remove it and weld in
new metal. Completely remove all rusty metal from the car, don’t cover any
up or the rust will grow. I use a Plasma cutter to cut the metal but
quality tin-snips or a nibbler will work just fine. If your car has some
surface rust than this is OK as the paint will completely seal it and
prevent it from growing further. Cut a piece if 18 gauge metal to cover
your rusted area that is about 1/4 inch larger than the hole. This metal
should be a plain steel and not have any coating such as galvanized. The
base metal should also be very clean for at least an inch away from the
weld. Use wire brush or sander to clean. As an option, you can add a
depression to the body metal for the patch to set in. A tool is made to
do this but car must be used. This tool only makes 3/4 inch long ridges at
one time and can cause some warping of the metal around the patch area.
The new metal must be completely welded in using a good mig welder. Low
current 110 welders just don’t do the job with the exception of the Lincoln
SP100 or SP125. I use a 200 Amp Century. Turn the welder up to a voltage
that would normally melt holes in the metal if welded continuously. Then
tack the metal in place using short bursts of weld (1 second) about every 4
inches around the patch. NEVER try to push the metal in place while
welding. The metal should fit the contour of the body naturally with only
a very slight pressure needed to hold the pieces together. If you press
hard while welding then you add stresses to the patch and will cause
warpage in the welding process. Once the piece is in place you can start
welding it solid. This is very important to do slowly. Weld in about 1/4
to 1/2 inch strips around the patch with one hand on the surrounding metal
about 3 inches away. Each weld spot should spaced apart around the patch
area. You keep doing this until you fill all the gap in. If the
surrounding metal gets too hot to hold you hand on then quit till you can
lay your hand over the area that is being welded. This process may take 20
minutes for a 6 by 6 patch area. If you rush the welding then the metal
gets too hot and warps. Sheet metal under about 12 gauge is made by a cold
rolling process. This process puts stresses in the metal that are released
in the welding process which will cause warpage. Keeping the head down
reduces this possibility. The weld should be continuous and not just
spotted. Moisture can come in from the back side and cause rust to grow
under the filler material and cause the filler to lift off. Grind the weld
lightly when done to reduce any high spots in the weld. Before applying
filler, rough up the metal with a 24 grit disk on a 7 inch grinder so the
filler has something to stick to. You may also want to use the pick hammer
and slightly dent the metal in around the weld area so that less filler is
needed to cover up the patch.
For surface rust in areas like the floor board where is has gotten deep or
has some Swiss cheese type holes less than the size of a pencil, then an
alternate to welding can be done. Use a wire brush to remove all loose
scale and sand away paint from the surrounding area for about 6 inches.
Clean up all dust with a vacuume. Apply POR15 metal prep to the area to
etch the new metal that is not rusted. POR15 will not stick to clean metal
unless chemically etched. But it sticks very well to rust. Apply a heavy
coat of POR15 paint over the entire area. Lay a layer of fiberglass cloth
over the rusted area and coat with another heavy coat of POR15. After the
paint is dry to the touch, add another coat and a layer of slightly smaller
fiberglass cloth. After it has dried to the touch then add 2 more coats of
POR15 alone waiting till the paint has dried to the touch between each
coat. POR15 is an amazing paint. It does not ever fully get hard. It
dries faster when it is damp out. It will not lift with the formation of
rust like normal paint will, and is so strong that you will NEVER be able
to peel that fiberglass cloth off again. The patch will be nearly as
strong as the original metal. The stuff is not really paint, but they call
it paint for lack of a better word. You can also use it for areas of heavy
rust on the body that has not gone completely through. Simply paint a
couple of coats over rusted metal before filling and painting. If you are
going to top coat the POR15 then you need to spray a light coat of primer
on it before it completely dries or sand it so the top coats will stick.
You don’t need the fiberglass cloth on an area that does not have holes
through. I also recommend using it on any are under fenders where rust is
on the back side and over the back side of the welded in patches. POR15 is
not the same type of product as those rust converters like “Extend”. It
does not convert the rust, but covers it up preventing moisture from
getting to the rust stopping any further growth. OH, and one other point,
Wear plastic gloves. POR15 sticks to skin like crazy glue. If it dries on
your hands you will wear it for about 2 weeks. I tried Acetone, Xylene,
Toluene, Methel-ethel keytone, Tricholrethene, gasoline, Alcohol, Lacquer
thinner, Carb cleaner, Brake cleaner with Hexane, Sand paper, and soap to
get it off and nothing works.
Now that all the metal is fixed we need to make the car smooth. There is
no need to use lead as filler. Modern plastic fillers will last just as
long as the paint job and are easier to work with. Besides, lead is toxic
and hard to find at times, hard to apply, hard to sand, and the acid flux
used can cause corrosion and paint problems. There are several types of
plastic filler. Fillers with Fiberglass threads such as “Everglass” are
for filling areas over 1/4 inch deep. These fillers do not crack when used
for deep fill. Regular plastic fillers such as Marhide “Golden Extra” is
the general purpose filler used to fill most dents and patches. Some
special fillers such as “Metal-to-Metal” are used in areas that may be
susceptible to cracking. These fillers are more flexible to resist the
cracking. There is also a fine fill Polyester glazing filler to fill small
imperfections and spots left from sanding or hail damage. These fillers
are made to be used either under or over paint and are the only type made
to do so. They should not be used in fill depths of more than 1/16th of an
inch. The generic “Bondo” brand filler is of OK quality, but is hard to
sand. You will find the Filler material you get at the paint store is not
any higher priced than the Kmart Bondo but is far superior in quality and
sandability.
Applying filler can be somewhat of an art in itself. Mix up slightly more
than what you will need. (this takes practice to estimate). Once mixed
properly, you will have about 3 to 5 minutes to work with the filler before
it starts to harden. Too much hardener will cause it to harden while
mixing or if you can get it on the car, it will possibly crack when if
cures because it hardened too fast. To little hardener will make it take
for ever to harden or might not harden at all. As a rule, a cup full of
filler uses about a half tablespoon of hardener. When mixed properly, it
will get unworkable in 5 minutes, then be sandable in 12 to 15 minutes and
totally hard after about 2 hours. It is chemically hardened and does not
require any time to breathe. Cover the entire area being filled past the
edges of what you think you will need. Once the area is covered work the
filler from the edges to the center using the plastic scraper tool getting
it as smooth as possible to the final contour. Once sandable, use a 9 inch
random orbit sander with 36 grit paper and work down the filler to the
desired contour holding the sander almost totally flat to the metal. If
you desire, you can stop slightly before the final height and use an air
file and 80 grit paper. Work the air file in random directions to prevent
cutting too much in one area. For some tight or rounded areas you might
also use a DA sander with 80 grit paper. Never use finer than 80 grit
paper sanding filler. It will take too long and the longer it takes the
more ripples you will get in the filler. Trying to sand the filler
perfectly smooth takes bunches of time to get it smooth and not get
ripples. Don’t worry about the deep sanding marks in the filler, as the
primer will take care of them. If you have to apply a second coat, then
the second coat should cover the entire area and not just the low spots.
If you cover just low spots then when you sand the new filler, you will
sand some of the previous coat making new low spots. Trust me on this one,
I learned the hard way. Another thing to remember about painting, you
can see low spots but not high spots in the finish. Therefor leave any
filler slightly high and don’t have a low spot. I learned this the hard
way also. It takes some practice, but filler can be easy to apply and sand
quickly. Unless it is a corner of edge, don’t ever sand filler by hand or
with a small sanding block. Your hand motion will put ripples in the
filler that will show up in the paint. To see how you are doing, hold your
palm flat over a piece of paper towel. Rub your flat palm (and the towel)
over the area you are working on while looking away or closing your eyes.
You will then “feel” the high and low spots that need attention. The
whole art of body work takes some practice to be good and fast. The guy
that taught me can fill a dent in a door in one coat of filler and it only
take him 15 minutes. That is about all I will say about filler as saying
any more might require a book to get all the information across.
Note: In the following procedures for painting, several precautions must
be taken. All the paints used are chemically activated and cured. If you
do not clean your paint gun at once, you will be buying a new one. The
paint will cure in the gun in a short time. I actually had the primer
setting up before I could get it all sprayed on. These new paints are also
more hazardous than the old lacquers and enamels. A dust mask is not
sufficient. At the minimum you should use a paint spray respirator. If
you are sensitive to chemicals or have some breathing problems like ahsma,
then you need to wear a air supplied respirator. This is the type where a
pump sits out side and pumps fresh air in to you. You could alternately
wear a scuba or firefighters air tank. These new paints are absorbed
through the skin and in reality, you should wear one of those white
painters suits when spraying paint. The most absorbed area for paint is
the eyes. Those little swimming pool eye covers work well if you do not
have a full face respirator. For most people, the exposure is low enough
for a single paint job, that the respirator is good enough, but it depends
on the persons system. It doesn’t seem to bother me, but my father can get
sick standing outside the door watching me. Use your own good judgment.
Also modern paints no longer have mixing instructions. You have to get the
separate instructions from the paint store. It is one way the government
is trying to persuade non professionals to not paint their own cars.
For painting you will need a paint gun. I use a Devilbis GFG517 which is a
normal flow gravity feed paint gun. The old suction feed guns are almost
useless with today’s paints. They are just too thick and heavy to spray
out of a suction feed gun. HVLP guns may be used if you wish, but I don’t
like them. They put the paint out in a rough finish in anticipation of
using a baking oven to make the finish smooth out.
Once all low areas are filled then we are ready to start painting. First
we need to cover up the bare metal to protect it. Mask all areas and
openings off with masking paper and quality 3M masking tape. Don’t use
news paper as paint will actually soak through the paper making a mess of
what is underneath. I use Ditzler DP40 epoxy primer. It mixes 1:1 with
the DP402 catylist. You could also use Dupont Variprime acid primer. Give
the metal 2 good wet coats allowing the paint to flash (gloss is gone)
between coats. You should even cover the plastic filler. The DP primer
should be top coated with the next primer stage within 24 hours and no
longer than 7 days. DP primer causes a chemical adhesion to the next coat
and the chemical reaction has ran out after 7 days and would require
sanding for proper paint bonding. I usually wait about an hour and apply
the primer. For primer I use Ditzler K36 Prima Urethane primer. You could
also use Dupont Uro-prime. It is as high a quality as the clear coat that
you will use and is a high solids paint. Mix it with 5 parts K36, 1 part
DU4 hardener, and 1 part DT860 reducer. Apply 2 to 3 heavy coats letting
each coat flash before applying the next. Let paint sit at least 2 hours
and preferably overnight before sanding. Where most of the time came from
the paint jobs of olden days was waiting on the lacquer primers to dry. To
prevent shrinkage of primer you would have to wait about a week between
sandings with lacquer to allow the reducer to completely evaporate. Plus
the old lacquers were not high build, forcing you to apply more coats and
sand more times. The only good Lacquer primer is the Ditzler Kondar primer
which is a high build and will dry in about 3 days. But lacquer should not
be used with modern top coats as they may react and reduce paint life. The
new Urethane primers are chemically hardened and require very little drying
time.
When sanding primer, apply a light mist of some dark color from a spray can
of lacquer. This is called a “tracer”. It is your guide to sanding the
paint. This procedure is called “Block” sanding. Use 180 grit paper to
sand the first coat of primer. You may think this funny, but use a 3 by 3
inch piece of Styrofoam about 12 inches long to sand with by hand with
sticky back 180 grit paper. The Styrofoam is straight, fairly solid, and
has just enough give to not dig in. By hand you will work the foam in
diagonal strokes trying to keep the sanding stroke at least 12 inches or
more. Work it in many different directions while sanding to prevent
cutting lines in the primer. You can also use the air file to sand the
primer with a 180 grit paper. Work the air file in a slow motion across
the paint changing directions often. For rounded areas, use a foam sanding
block or the palm of your hand. Avoid using fingers to sand, but rather
use the whole palm. If you sand with fingers you will cut little groves
that you will see in the paint later. When sanding with a small block or
by hand use rapid motion with very light pressure for best results. What
we are looking for when sanding the primer is the removal of all the tracer
coat. Once all evidence of the tracer coat is gone, then we can stop
sanding. Just like the filler, the more we sand, the more likely we are to
get waves in the paint. As you sand over the filled area, you will slowly
see the those massive sanding scratches go away. If while sanding, you
reach primer or metal before all the tracer coat is gone, then stop sanding
there as you will need to add more tracer coat. If you have an area that
is real low or you have some “chip” spots then these can be filled with the
polyester filler I mentioned earlier. Just mix and use as little as
possible for the fill. Sand the filler with 80 grit using the 9 inch
random orbit sander, the DA or the Air file. Once the primer is done with
180 grit, add more primer. If you still had tracer paint or you had to add
more filler, then apply 2 heavy coats. Wipe of blow off all dust before
applying the next coat of paint. Just like the filler, paint the entire
car again and not just small areas, although you can actually apply the
paint a little heavier in the areas that you know are low. Repeat till you
have no tracer showing. If you have no more tracer showing, then apply 1
heavy coat. When dry, sand with 400 grit paper by bare hand using water.
Use 600 grit if you plan to paint with a metallic color. You will again
want to use a tracer coat for sanding and sand till all tracer is gone.
You should now have a very smooth car ready for final paint.
Remove all the masking paper from the car. You will have to add new stuff
for the final paint. Dust in the old paper can get in the paint and ruin a
paint job. Using an air hose, wipe the paint off with a rag while blowing
the dust you are wiping away. If you wash the car with water, make sure it
has a couple hours to dry before painting. It will take you some time to
mask it off anyway. Use the air hose to blow air in all areas of the car.
The head lamp doors, under the fenders, the cowl vents, everywhere. Go
around the car about 5 times blowing it off. If some dust is left in a
crevice some where, odds are it will end up in the paint. Once you are
done blowing all the dust off the car, reapply the masking paper. Paint in
a well ventilated area. If in a building, then there should be a powerful
fan blowing the paint fumes out with an opening on the opposite end to let
fresh air in. Let this fan run while blowing off the car and for about 1/2
hour after to suck all the dust that is airborne out. Now is the only time
to sweep the floor. From now on out, you do not sweep the floor till done.
If it is a calm clear day, you can even paint out side. But any dust
kicked up and carried by the wind will get in the paint. Once everything
is clean and the car is masked off, wet the floor well with water. This
keeps dust that is on the floor on the floor. If the floor dries out it is
OK because the water makes it stick to the floor even after dry kind of
like dust sticks to the car after it rains, i.e. rainspots. Just before
getting ready to paint, wipe the car down with a tack cloth. Unfold the
cloth and use very light rapid wiping. Pressing too hard will make some of
the stuff in the tack cloth stick to the car which can mess up the paint
job. With our fan running and respirator on, apply 2 light to medium coats
of DP40 epoxy primer as a paint sealer. You cannot use the Dupont
Variprime as a sealer. If you desire the DP40 can be thinned with up to
100% DT860 or 870 reducer to make is easier to spray. If you do reduce it,
then you will have to wait a couple of hours before applying the color.
Non reduced you can topcoat in about 30 minutes. If you are using a dark
colored paint, then you may want to use the DP red (#74) or Black (#50?)
instead of the #40 grey-green. No sanding is necessary before applying the
color coat.
You have several options of top coat. The oldest is Lacquer. Lacquer was
once the paint of choice for show cars because it went on easily and could
be buffed to an incredible shine. However, about 1980 they took the lead
out of automotive paint and Lacquer has not been worth a C*** ever since.
Up into the 80s GM cars were painted with non clearcoat lacquer. That is
why some of those mid 80s GMs peel and flake so bad. You can still use it
but it will not hold a shine very well and will tend to crack an cobweb
easily with time. Most lacquer finishes are clear coated but don’t have to
be. For lacquer, you apply color till “hiding” is achieved, usually about
3 medium coats. Then clear is added. Lacquer is thinned with the
appropriate temperature thinner at 100 to 150% ratio. For non sanding
applications, use about 3 coats of clear. If you plan to sand the clear
and buff it, then apply 6 coats as you will sand 3 of them back off. Apply
the paint “wet” and overlap each pass 50% for best results. Don’t be
afraid to lay the paint on heavy. If you paint too slow, they you will see
dull spots and roughness or “orange peel”. For lacquer you will have to
wait about a month before sanding and buffing.
The next paint of generations is Enamel. For enamel to work properly, it
must have a hardener added. This hardener will add some hazards to the
paint above that of just the Enamel itself. If hardener is not used, then
the Enamel will takes weeks to get really hard and the whole time it will
be very easy to scratch. Enamel should not be sanded and buffed. Doing so
will actually reduce the shine and the life of the paint. Enamel is
applied in about 3 to 4 medium coats thinned with the appropriate
temperature reducer at about 100%.
Next came Urethane single stage paint. One of the earliest of this is
Dupont Imron. This paint is mixed with a hardener and reducer just like
the primer. It is applied in the same manner as Enamel. However, this
paint may be sanded and buffed if desired. If you plan to sand and buff,
then use 5 coats instead of 3. This is good paint for doing under fenders,
in the engine bay, and suspension parts as it will shine well with little
waxing and does not need to be buffed.
By far the best top coating is the Basecoat-clearcoat. There have been
several varieties in the past. One of the best is either the dupont Chroma
base or the Ditzler Concept 2000. I painted my car with the concept 2002
clear and DBC basecoat. For the Ditzler, mix the basecoat 100% with DT 860
or 870 reducer. Apply 2 to 3 wet coats. This paint will cover fast. It
will spray with the look of cottage cheese but will smooth out as it dries.
Too dry of coat and it will not smooth out. Too wet of coat and you will
get some runs like I did. If you get runs in the base coat, then let it
dry about an hour and sand with water and 1000 grit paper. You can then
apply a little more color to the area where the run is. Since the basecoat
is not really a hardened paint, you can spray in a little area and it will
mix in. As a matter of fact, you can just spray DT reducer over the area
and the run sometimes will just melt away. The Base coat is very fragile
and even after a week can be just wiped off with a rag of reducer. It
requires the chemicals in the Urethane to make it harden. Therefore, the
base coat is not sanded prior to clear coating. Once the base coat has
flashed off, mix up some Clear and get ready to spray. For the Concept
2002, mix clear at 5 parts, DXF11 hardener at 5 parts and DT reducer at 1
part. It took me about 2 and a half quarts of clear for the whole car.
Spray clear with 2 very heavy coats letting it dry to the touch between
each coat. This clear is applied to just before the point of running. It
may appear a little rough in appearance, but you will be sanding it out.
The paint will look like cottage cheese as it is sprayed but within a
minute will level out. For optimal results, after the car is painted, it
is baked at 160 degrees for about 4 hours. Doing so will cause the paint
to “float” out and get extremely smooth. This is the way the big paint
shops get all the orange peel out of the paint that is caused by the HVLP
guns. It is also the way the new car makers are getting the new car paint
jobs so smooth without buffing. This clearcoat can be sanded within 8
hours of painting and should be sanded and buffed within 72 hours but no
later than 7 days. If you wait more than 7 days, the paint gets so tough
that it is near impossible to get all the sanding scratches back out when
buffing.
All masking paper should be removed after about 2 hours. Waiting any
longer may let the paint get too hard and cause it to chip at the edges
where the tape is. When painting 2 colors such as the rocker panels, the
masking is applied directly over the previous color coat. Wait about an
hour for the previous color coat to dry and then mask off for the second
color. Be careful peeling tape back off so as to not pull away any of the
fresh color. This is one reason why only good quality 3M painters tape
should be used. It is also advisable to use “Fine Line” tape at the paint
edge. This will make a finer edge where the two colors meet. Fine line
tape also will bend in curves easier than masking tape. This is the stuff
those guys use to paint those wild flames on cars.
Sanding clear coat is similar to sanding the 400 grit of the primer just
before the painting of color. Use the palm of your hand with either 1000
or 1200 grit paper and water. Work in circles and sand until all gloss
from the paint is gone. You will see specks of gloss disappear as you sand
out the rough areas. If you don’t sand enough you will still see it as
rough when done buffing. Be careful on edges so you don’t sand through.
Often I don’t even sand the edges of the paint for this reason. You have
to be very careful buffing. A power buffer can burn paint if worked too
long or fast, or can cut right through edges. Use a cloth pad on a
variable speed 0-2500 rpm buffer. Apply power buffing compound to the car
in a small, 2by2 area. Run the buffer slow as it will go and work with
medium pressure over the area until the compound starts to dry. As it is
drying, increase speed to 1500 rpm and use light pressure buffing the paint
to a gloss. Often it takes doing this 2 or 3 times to remove all the
sanding scratches. You will still see marks from the buffer so don’t
confuse them with sanding marks. When getting close to an edge, always
make the buffer wheel roll “off” the edge and not onto it. Tilt the buffer
if necessary. A buffing wheel running onto an edge will rip right through
paint. If the buffer is not working the finish up to a shine then the pad
needs cleaned. Hood the buffer running and use a screwdriver to scrape
away at the pad gently to remove the polish buildup. Be careful not dig
into the pad or rip the screwdriver out of your hands. Do this to the
entire car. Wipe the car off with a clean cloth. Change the wheel to a
Foam pad. Use the Foam pad compound for the color of the car. Compounds
are made for light and dark colors. Work this pad similar to the cloth
wheel. This pad will remove all swirl marks from the cloth pad. Again
wipe off the car with a dry clean cloth. It should now be looking pretty
good. As a final finish, apply some type of professional finish enhancer.
I prefer to not use any wax that contains silicone as it builds up on the
paint. Eagle 1 carnuba was is pretty good and smells kinda neat too. It
is the stuff Reces Pieces candy is shined up with. Don’t believe me? Look
in the ingredient list. You now have a 95 to 100 point paint finish.
In summary:
For a professional working 8 hours a day:
1 to 2 days to strip car of parts and paint.
1 day to weld up holes
2 days to apply filler and smooth (1 day for most guys)
2 days to apply and sand primer (1 day for most guys)
1 day to apply finish
1 to 2 days to sand and buff.
(dont hold your breath because you’ll more than likely passout)