Paint removal on magnesium?

[Mike Switzer]

Thanks for that link - very helpful. I just got off the phone with TP tools, (I have one of their blast cabinets) they have a plastic media that they say will take off any paint, dirt, or corrosion and will leave the surface smooth as original.

[Bill Berson]

I wouldn't alodine and then use self etching primer.
Self etching primer is for raw metal.

[Mike Switzer]

I wouldn't alodine and then use self etching primer.
Self etching primer is for raw metal.

I don't know that I will do all that, this one is getting restored as a nice driver, not a show car. As near as I can tell, originally they didnt prime them, they just masked off the bits they didn't want paint on & shot a coat of black enamel on everything else, front back & inside. Gonna do a bit more research into the coating options.

[martymayes]

A chemical stripper or blasting media that is not supposed to damage the substrate will remove the shine from a polished surface but it can be buffed back to shine like new. It's just a matter of expending the elbow grease.

[Bob H]

Magnesium is galvanically reactive so that if you clean the surface and expose fresh material, it will oxidize quickly with a dull finish. That oxide can react with moisture to produce undesirable intergranular corrosion which will induce cracking under stress. You want to generate a protective coating on the metal which is why Dow Chemical came up with Dow 7 as a coating to be applied immediately after machining.
The Dow 7 makes a protective oxide that resists the corrosion and keeps the mag from developing those cracks. It's similar to Alodine. If you blast the surface, have the proper coating available for quick application.

[Bill Berson]

I know they called them Mag wheels. But aren't they usually actually aluminum or a mixed alloy?

[Mike Switzer]

Magnesium is galvanically reactive so that if you clean the surface and expose fresh material, it will oxidize quickly with a dull finish. That oxide can react with moisture to produce undesirable intergranular corrosion which will induce cracking under stress. You want to generate a protective coating on the metal which is why Dow Chemical came up with Dow 7 as a coating to be applied immediately after machining.
The Dow 7 makes a protective oxide that resists the corrosion and keeps the mag from developing those cracks. It's similar to Alodine. If you blast the surface, have the proper coating available for quick application.

Thanks - I will look into that

[Mike Switzer]

I know they called them Mag wheels. But aren't they usually actually aluminum or a mixed alloy?

Most of the aftermarket pieces are aluminum, but some OEMs used magnesium thru the early to mid 70s.

[Bob H]

The term "alloy wheels" means they are an aluminum casting. "Mag wheels" refers to cast magnesium. You stated that wheels were magnesium which is what all the discussion was about.
If wheels are actually aluminum, no sensitivity to cracking and no special Dow 7 conversion treatment required.

[Mike Switzer]

These are original magnesium wheels, which was why I started the thread as I have no experience removing paint from magnesium. Sorry for the confusion, my previous post was in reference to Bill's question. Most alloy wheels are aluminum, but some of the the British manufacturers continued to use magnesium thru the early 70s.