Im going to watch this, I have a pair of Magnesium Wheels I need to strip and re paint. I have heard all kinds of things from cooking out moisture at 300deg, special Zinc primer/ sealer to keep them from reacting, DOW 7 Chemical conversion, etc. I looked at Aircraft Spruce but got lost in all their products for reconditioning Magnesium.
I've been told by the shop working on my car that there is a hairline crack (I'm not sure were) but they think can be welded however they don't want to do it. I also wanted the drill holes on the outside rim filled in. Then just polish them up.
Just a quick google search and I found this - http://www.woodyswheelworks.com/autowheels.shtml I have no idea who they are or anything about them, but might be worth checking out?
Tyler, Dow 7 is a conversion coating, not to be a final finish. It just ended up that way. Depending on your alloy, depends on your results/color. Here is a link. http://www.chemical-supermarket.com/Dow-7-Magnesium-Treatment-Compound-p652.html
You may want to have both wheels (completely) Zyglo tested, there could be many more cracks that are not readily visible.
You might check out this thread by Brian Bass: https://www.jalopyjournal.com/forum/threads/tech-the-black-art-of-welding-magnesium.184445/
Zyglo testing looks interesting, like a liquid magnaflux. I need to paint mine, so If I understand the process correctly; Strip (Non Abrasive), bake to remove all moisture and contaminants, Dow 7 coating, then whatever top coat I want. They need to go back to factory silver for my project. Carrosr, Mag can be welded, but if you do the holes on the rim, it will probably show as a shadow when you polish them. Were you planning to re-paint the centers too?
There is a welding shop in racine that welds magnesium. The chemicals to dow 7 can be bought at aldritch chemical in milwaukee or there is a shop in chicago that will do it for you.
Put slotted head screws in the holes like the guy who drilled them intended. Absolutely period correct.
Magnesium is terribly porous and requires a good thorough paint inside the wheel to seal them from slowly loosing air. I had a set of mags and one would invariably require weekly air top up. I had the tire shop tank test the mounted wheels and found there were several tiny holes near the bead. After much research, I ended up talking with helicopter mechanics knowing they encounter these metals routinely. They recommended two part epoxy primer such as PPG Deltron DPLF mixed with DP401LF or DP402LF Catalyst.
All the magnesium wheels that run on the cars in my family are bare, no paint. But, they all have tubes too. I've heard of guys painting the insides, as well as clearing the outside after polishing, only to have corrosion that is trapped underneath making small trails and flakes in the paint. Evidently you would need to perfectly clean and immediately paint the magnesium to prevent any atmosphere from starting the new corrosion. As any mag wheel owner knows, it doesn't take long at all for the "patina" to start.
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