powder coating

[cbrown@xxxxxxxxxxxxxxxxxxxxxxxx]

Brian asked about powder coating

on my 67 coupe, all black bits on the car , suspension, diff, prop shaft,
gearbox mounts , engine mounts, boosters .... have been gloss black powder
coated. The finish is very durable , 7 years now, the gloss  rolls off slightly
but looks very clean still.

The prep is important, blasting is required, the degree of surface coarseness
can affect how thick the sprayer decides to build. Zinc passivated plating after
blasting is not required, and many pc's dont like it to be done, although I tend
to think it ultimately gives a slightly more vitreous finish to the pc, why is
an unknown. 

The real issue is finding a good powder coater. A good one will store your bits
in a dry room if you deliver them blasted. Good pc's will not have blasting
facilities on the premises (dust), but farm it out. If you have it done yourself
then you can check it is correctly done. I did turn up to one  pc to pick up
some bits , which fortunately were not ready, but had been blasted by his
contractor, to find them with patches of surface rust still present. Lesson
learnt, I left with my bits to find another powder coater.

It is worth just getting a couple of things done initially to check the finish.
Many will be unconcerned about dust embedded in the finish. I tried six
different pc's before I found a good one. The powder is polyester, sprayed
electrostatically, there is  a potential difference between the work and gun,
more equals thicker. The powder gets up insisde all blind holes etc, so proper
masking is imperative, eg bolt holes/threads, bearing lands etc. (masking tape,
old bolts...). It is VERY difficult to remove powder coating from places it
shouldn't be. Once coated, the pieces are baked (ca 200 degC), not enough to
affect spring temper I am told.

 The advantage is an even coat on all surfaces, no 'throw/shadowing' issues like
electroplating, no runs like painting (on a bad day). It is also cheap, $2-3 per
piece typically. Resistant to most everything chemical likely to be encountered
(brake fluid...). the finish can look a bit plastique to some eyes if done too
thick, like a bad 2-pac spray, so shop around. 

regards 

chris brown

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