Folks,
I've been powder coating for a long time and have run across this issue many
times. Cast aluminum is the worst offender and the way to prevent it from
happening is to preheat the part at >400 (or whatever the powder cure temp
is specified to be) for an hour or 2, let cool, and then apply powder. I
just finished my '60s vintage aluminum Dunlop wheels with no issues.
On the subject of finish roughness, powder coating is just like paint in
that it will flow-out and reveal imperfections. I have used something
similar to Alumalead which is an aluminum powder based filler with good
results. After a quick search though, I found this product which is made for
powder coating:
http://www.thermobond3.com/
Hope this helps,
JVP
Joe Parlanti
'66 Tiger Mk1A B382000026
'59 Abarth Zagato 750GT
-----Original Message-----
From: tigers-bounces+parlanti=comcast.net@autox.team.net
[mailto:tigers-bounces+parlanti=comcast.net@autox.team.net] On Behalf Of
Cullen McCann
Sent: Friday, March 28, 2008 11:30 PM
To: Curt; Tiger List
Subject: Re: [Tigers] power coating
One thing I experienced in powder coating was an element called
"off-gassing"
which I think basically means that certain metals, in my case it was a late
model cast aluminum, will dissipate heat or some vapor out of the pores and
bubble the coating during the baking process. It might be percieved as
pimples
or bumps in the finish. There are other types of coatings that can be used
if
this is a problem.
U might check with your coater to see if this could be an issue.
Cullen
B382001452
Snip ...
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