Can I take a minute and try to put this all in
some sort of context?
First Matt asked:
"Inexperience question here.
My understanding regarding backing
(baking?) is that it is
intended to drive off the volatiles in the freshly applied paint. Is this
correct?"
Matt, yes it accelerates drying process by
evaporation of the chemical drying agents in the paint, Jerry Glow could
explain it better as he is a former auto body repairman. The same baking
techniques are used to do the same to prototype freight equipment, it is
the application that differs.
"Also, I believe I read somewhere that letting a freshly painted model sit
for several days (or longer) would accomplish the same thing - only
(obviously) slower...
Good thread.
Matt Goodman
Columbus,
Ohio"
That could be true but the heating process
makes the enamel dry harder quicker. As I have said I don't bake my brass in the
oven but I do in natural sunlight under supervision or under a 60 watt bulb
perhaps overnight in winter. If I want to bake solvent based enamels on
plastic I dry them in natural sunlight with extra supervision as the
combination of the solvents and the heat can soften
plastic
The Peter adds:
" I had been lead to believe that baking paint like Scalecoat, would
actually improve the adhesion of the paint to brass."
Not really, adhesion would improve if you do as
Schuyler and Mike mentions by lightly etching the surface chemically or with
"grit blasting"
"I know from experience that baked on lacquer and enamel paint resists
scratching better.
Pierre
Oliver
www.elgincarshops.com
www.yarmouthmodelworks.com"
True" enamel" by it's nature/name is expected
to be harder, the same with lacquer-based enamel, which would leave one to
believe it would resist scratching better.
Bruce writes:
"Matt,
Baking is only appropriate for enamel based paint."
Wait! I have an issue with this statement and it follows
along with the use of the term, "Dulux Gold", Dulux is a brand not a
specific color and enamel is referenced to a hardened
surface paint not to a "base" of a paint. There are lacquer,
alkyd resin, or poly-vinyl acrylic or latex vehicle based enamel paints...
"There is a school of thought that says that it causes the paint
to "cure" or polymerize, which may well be true. Never ever bake plastic or any
metal that might melt (like some weights) and do not bake acrylic paints.
Baking an enamel paint job will allow you to move on to the next
application more rapidly.
Regards
Bruce"
I am not sure why you wouldn't bake an
acrylic/latex or poly vinyl acrylic paint as it would help the surface dry
harder and as the late owner (his name escapes me Greg K??? help me out
here Dennis) of ACUFLEX paint recommended you do exactly that because he
reminded me that, "acrylics are like Spandex and shrink to
fit..." He was right his paint went
on what seems to be "goby" and once the surface was heated it shrunk incredibly
tight to the surface. Wonderful stuff.
Schuyler
replies:
"Pierre is correct. When I have baked Scalecoat 1, the resulting finish is
harder, glossier, and more resistant to scratching than any other paint I've
used. Allowing paint to dry "until the odor is gone" works OK, but it will not
give you the same durability of finish. It will scratch more easily and wear on
grabs and other wear points."
Schuyler reinforces the point that baking
results in a harder, glossier and more scratch resistant finish and
testifies that Scalecoat 1 is the "one". No Contest here, I don't want to
start a "my doges better than your dog" thread,
The point is that heating the paint to a given
temperature and holding it there for a given period of time does 1.) gas off the
vehicle quicker, 2) promoting faster drying, 3) and enameling the surface
faster. In the case of acrylic paints it "sucks" the paint
tighter to the surface. An equally hard surface can be achieved in
time if allowed to simply air dry.
"Bruce offers "polymerize."
Maybe. I don't know if that's what it does or not. But whatever it does, it
works.
Schuyler"
Greg Martin
