Painting/powdercoating magnesium wheels

Thanks for the replies; I'm leaning towards painting just in case there's a problem, and leaning that way further now.
Good idea about heating them to gas off impurities; I doubt the powder coater will do that so I can take the wheels away and paint them, but I could probably do that in my oven (or maybe not). From what I've read on mag, annealing it and letting it cool is required after machining or cutting to avoid stress risers, but nothing I've read on the topic so far talks about impurities, or whether mag continues to out-gas or blemish if painted. I know of a set of Halibrands that showed some blushing after being powdercoated clear, and the clear actually yellowed; maybe that was the mag continuing to degrade or affect the clear?
They'll need to be color-coated I think because of the stains, and I'm thinking a flat or satin clear over that for protection.
I'm going to refinish the aluminum rear wheels the same color, but I'm not expecting problems there.

hi i do powdercoating, everything i coat, will go in the oven before i coat it, on cast aluminum (wich is close to magnesium)to prep it for coating, i only blast it with aluminum oxide, then cook it,blast it again,clean and prep it for coating, reheat it to make sure it has out gassed,bring it to 300degrees and shoot it hot.

i find the biggest problem is water,oils or solvents can be removed with just about any thing and remnants can be burned off, just like when welding aluminum or mag the part needs to be preheated to remove water.

Jimi, are you able to come close or match the old DOW 7 look?

http://www.jalopyjournal.com/forum/showthread.php?t=235753

So, Jimi -
If I understand you & the article Hemifred posted correctly, a good cleaning with wax & grease remover, scuffing the old coating off with red Scotchbrite pads, a decent baking to be sure there's no water, and I can paint the wheels?
I'm really reluctant to have the mag blasted with anything for fear of pitting. Likewise I won't let water get anywhere near them in their bare state.
Seems I should use an etch primer; whaddya think?

if you use aluminum oxide shot it will not disturb the finish of the wheel,years ago when we painted the modified mag crossrams for the s/s hemi cars we would coat them with a zinc primer, the zinc primers were supposed to be for steel but there was a reason it was used and i cant remeber why.

Jimi, thanks for the reply. One problem where I'm at is I don't have access to a blast cabinet anymore, and the local blaster guys are (a) reluctant to use anything but soda, plastic or really aggressive stuff, and (b) so far the workmanship is not good enough to trust $800 worth of damn-near irreplaceable wheels too. Can I just scuff through the oiling (wheels were pickled & oiled decades ago, boxed up since) and then etch-prime them for painting?

"Find it, and they will come." This may be a foolish question, but has anyone tried the actual Dow 7 on aluminum?

Steve,
If you don't mind a little work, I spray my magnesium Motorwheel Flys with GIBBS penetrant after I polish them with scotchbrite pads. It works better than WD40 as it does not attract dirt and does prevent oxidation for several months.

Mike -
Thanks, I've heard about the Gibbs stuff. The fronts I ended up with used to be on the Gapp&Roush Taxi, but they were pickled & oiled, and subsequently stained with something, so I need to paint them. I'll paint all 4 wheels the same color.

El Bumpo

And another, still curious as to best method to remove the surface coating my wheels have. I have a 2nd set that were painted, and I'm thinking I'll just soak them in lacquer thinner, or maybe try aircraft paint stripper, to get rid of the paint.

brake fluid works also