Hello Andrew
Watch the temperature used with powder coat, you can kill the temper on
aluminium parts. Some powders require temps too high for tempered
aluminium. Even if you have a lower temp powder, make sure oven does not
overheat part. I didn't powder coat anything as of this moment, but if I
do, will use Thermal color indicating telltales along side my parts to
make sure over temp did not occur.
I fooled with at least a dozen cans of spray primers, self etch, zinc
oxide and zinc chromate. Also fooled with Dupont self etch in gun.
Some cans work OK as far as adhesion and things went downhill from there.
The Dupont stuck OK, but either the DPLF or DCC did not adhere well to it.
Most companies do not advocate using other companies product. I think
scuff sanding was part of the problem with the self etch, it filled the
sanding scores and volatiles were probably trapped because it was on too
thick in those areas.
My choice of paint is PPG DELTRON
http://www.pwpaints.com/ppg-p-sheets.html
DPLF as the Epoxy Primer can be used on metal and airframe. On airframe I
apply a very thin coat as an adhesion promoter, then wait for a full cure
(many days), then light scuff and K36 high build primer to fill, then DPLF
to seal and DCC Concept as top coat. The reason for DPLF on airframe first
is as a adhesion promoter, and an attempt to seal porous surface from
volatiles getting trapped if I were to use K36 first. Put paint in direct
sunlight and let it heat up, and pimples will appear if you have volatiles
hidden below your spectacular paint job.
On metal, trying DCC on top of all the primers I tried works from OK to
poor. Not great adhesion. I tried DPLF on top of the primers then topcoat,
and again OK to poor adhesion.
Scuffing metal and putting DPLF on it, WOW. It sticks incredable. On all
metal parts they get sanded or sand blasted with Aluminium Oxide media,
DPLF, and then top coated. If metal is permanent stuck to the airframe,
they just get painted along with the airframe. If needed you can use K36
high build primer over DPLF to fill imperfections on metal.
Make absolute sure that the volatiles have evaporated before putting on
next type of paint. That includes whatever you decide to clean surface
with. If you were to topcoat too soon over a not full cured primer,
adhesion would be not too good between paints. You sometimes can peel
layer off and actually smell volatiles years after paint.
Just a side note, JB Weld (JB KWIK) is a great pinhole (and scratch)
filler. It is very thick and stays put. If you use a 1+1/4" flexible putty
knife to apply and scrape, then a very sharp razor blade to squeegee, all
that is left is pinholes and sanding marks filled. Amazing. The regular JB
Weld long cure is not as thick and does not work anywhere near as well. JB
KWIK is harder to sand than Expancel, so not a great idea to fill anything
other than pinholes or scratches where you can squeegee off almost all
excess.
Good Luck
Ron Parigoris
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