Date: Fri, 26 Jan 2007 21:00:57 -0500
From: "Paul Dorsey" <dorpaul@negia.net>
Subject: [TR] Powdercoating?
List, Hey Paul: See my comments/answers injected into the body of you
email. Bob
Over a year ago, I had a closeby Powdercoating Company to Powdercoat my sills
white and my floorpans black. However, now that I am installing these pieces
there seems to be more of a difference between these pieces that is more than
just a change in color!
Underneath the glossy white exterior is a thick layer of dried powder. This
shows why powdercoating is called, 'powdercoating'. Wrong! Something is not
right here. Once powdered & CURED correctly. There should be no dry powder
anywhere. Just a FYI. Most powders cure around 390F, but the dry powder starts
to get wet & flow out at about 300F. A mistake many hobby powder coaters
make is by curing the powder at oven temp. The correct way is to use an IR
thermometer & know that you substrate is up to temp (390F), then you start you
cure schedule timer. By only curing with the oven temp you don't get a proper
cure. So maybe that is why there is dry powder under? But to be honest, I have
never seen that happen. But something is for sure not right.
However, under the black floorpan's flat black exterior is simply the metal
it
covers. Sounds like the black coating is correct. No Powder at all! I
instructed them to 'powdercoat everything' but,
did I get gyped instead? Or maybe their is a a type of flat black
powdercoating that doesnt have the powder? No. There is no dry powder left
after a correct cure temp & time. I would go & ask them why the white is still
showing dry powder. Your issue is the white, not the black. A simple test to
see if your powder coat is cured correctly. Take a rag slightly dampened
with MEK or even acetone. In an area that might not be so obvious take the
damp
rag & swipe it lightly (about 20 swipe passes) over the cured powder. If the
finish gets dulled or any discoloration, the item is not cured correctly. If
no damage, you got a good powder job.
Could that be true?
Thanks, Paul Dorsey
Good Luck
Bob
_www.capecodpowdercoating.com_ (http://www.capecodpowdercoating.com)
_www.capecodbritishcarclub.org_ (http://www.capecodbritishcarclub.org)
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