[DeTomaso] Wheels

[JDeRyke at aol.com]

In a message dated 1/26/12 6:50:31 AM, michaelsavga at gmail.com writes:

> Does that heating process ruin the finish and require repainting?
> 

Yes. The aluminum paint turns tan at 375F so it also need to be re-sprayed. 
FWIW, I got the annealing info decades ago from Lockheed. Their mag 
annealing method involves 375-390F for 2 hours followed by very slow cooling. You 
can safely do this in your home oven as mag autoignition temps are 3X this 
high. Some powder coat shops will dry their powder painted mag wheels for 2 
hrs, then wrap your freshly painted wheels in blankets (or let you wrap them) 
for the mandatory slow cooling.   Needed every ten years or so on magnesium 
wheels.
Magnesium, also known as "compressed corrosion" by engineers, age-hardens 
and most mag is gravity cast so the metal crystals are quite large. Perfect 
for age-related stresses to build up until a pore or a crystal generates a 
micro-crack. Then the casting unzips like plastic wrap. The same thing happens 
in trying to weld-repair a crack in mag that's not stop-drilled; 
temperature expansion propagates the crack faster than the welder can add metal. Good 
luck- J Deryke