This is my first post here and I joined to get some insight into the process of refinishing magnesium parts. I'm surprised to read the advice on campis here because most of what I've read elsewhere differs. Cromodora wheels (often found on Ferraris and Fiats) are also magnesium. Originally they were pretreated with a chromate solution made by Dow (who are out of the business now) then they were painted. As I understand it, if you blast or strip the wheels down past the Dow layer (a greenish/bronze colour) then you really need to pretreat it again. Henkel/ Bondrite make a Dow equivalent called Alodine but the chemicals are pure evil. (Steve Kouracs in his mag wheel tutorial mistakenly lists Alodine 1200 - which is only for aluminium not magnesium)
alodine® T 5900TM – Trivalent chrome conversion coating approved to MIL-DTL-81706/MIL-DTL-5541F Class 1A and 3.
I'm considering using a non-toxic pretreatment instead from Pantheon chemicals called PreKote instead.
What mystifies me is what I read here about using zinc phosphate. Does anyone know what the chemistry of etching or using this zinc phosphate is? I thought magnesium was the most reactive metal there was so shouldn't be coated with anything containing another metal. Pretty sure thats why the air filler is rubber and not steel too.
I want to treat my mags safely and find it hard to figure out which way to go. Any advice welcome, thanks.