Reply to "Refinishing Campi Wheels"

The best alternative to Zinc Chromate (which I understand is getting hard to find because it is supposedly a carcinogen) is to powder coat the wheel. Without Zinc Chromate to seal the wheel first, ordinary paint is insufficient. The added benefit of powder coating is that the temperature used is about the same as that required for annealing. Also remember that, in order to anneal properly, the wheel must be cooled very slowly. This is best accomplished by making sure the powder coater does your wheels as the last job of the day, and leaves them in the oven to cool overnight.

No matter what, you will need to bake your wheels before powder coating or painting in order to bake out the contaminants, or else you will get outgassing that will ruin the finish.

Before painting your wheels, make sure you have them Zyglow (dye)tested for cracks. The wheels are prone to cracking for two reasons. First, unless they are regularly stress relieved through annealing - which most people don't do, magnesium work-hardens until stress cracks appear. Second, any scratch (such as a curb scuff or scratches from wheel weight mounting) will allow moisture and contaminants into the porous magnesium, which will immediatley start corroding until it is weakened to the point of cracking. Now that your wheels are probably more than 30 years old, they really should be checked. I have heard it said that they should be done every ten years, but I think that is probably too cautious.

Cracking and other damage can often be repaired, but make sure you give your wheels to someone who knows magnesium. Welding magnesium is both tricky and dangerous. Always be sure to stress relieve after welding, because the heat from the welding causes stress in the material that needs to be released.

Do your refinished wheels a favour and use adhesive wheel weights. As I already mentioned above, clip-on weights will scratch through your nice new finish, and allow contaminants into the magnesium, which will immediately begin to corrode again. Another trick I use is to lubricate the hub before mounting the wheels (I use Vaseline but maybe others will have better ideas on this)because this is another area where corrosion tends to occur. I'm not sure my Vaseline idea will help, but I'm hoping so because damage to the hub is often impossible to repair. Finally, I am very picky about who I allow to mount my tires. The last thing you need is to have some idiot in a hurry scratch your new finish or, worse yet, break your wheel.

Mike Drew and Jack DeRyke have written excellent articles on refinishing magnesium wheels. If you want copies, PM me with your e-mail address and I will send their information to you. Or you can contact them directly.