The guy does $50,000 show bikes, including full-on restorations. He knows how to powdercoat :wink: The problem is in the substrate of the castings. Yes, <sometimes> heating the wheel to a temperature above the cure temps of the powder will release those impurities. Sometimes it doesn't. Tried three different times, same results. Didn't want to go too high above the cure temps for these wheels, since there is a possiblity of heat induced cracks developing. Not an issue with steel parts, but with aluminum castings it is a <possibility>.
A356-T6 Aluminum alloy is cured at only 325 deg f. Exposing that alloy to temps much above say, 350 or 400 degrees for as little as ten minutes will compromise strength. The thought of a front wheel crack while in the middle of an 80mph decreasing radius turn led to my decision to keep the temps regulated and the number of heat cycles low.
Cratering, or blistering or whatever you want to call this is not common, but does indeed happen. Usually with aluminum castings and especially if they are full of impurities. Five years on calcium dusted roads (calcium is reactive with aluminum) will cause impurities to leach into these porous castings, making powdercoating nearly impossible. Using fine steel wool to clean the wheels impregnated steel particles into the rims, further compromising the powdercoating process. To suggest that <every> aluminum wheel can be powdercoated if the coater <knows what he is doing> is not really accurate. A professional coater knows when to throw in the towel. An amateur doesn't.
The typical Goldwinger does indeed clean his wheels occassionally, I have cleaned them maybe three times in five years. The typical Goldwinger doesn't dare take his bike out in the winter, or on salt and cloride infested roads. I do. Those decisons led to the tragic results of having really, really, nasty looking rims.... :wink:
Good news is that for a mere $345 I bought two brandy new factory rims.....Should be good for another five years of abuse!
