Summary for polished aluminum corrosion Discussion
The focus keyphrase, polished aluminum corrosion, fits this thread well because Jevan Fazekas asked about a white crusty deposit on uncoated polished aluminum rims after driving on salted roads and wanted to know whether a stronger cleaner would help. Ted Mooney, P.E. replied that the problem is not simply salt residue: polished aluminum can pit and corrode, creating salt-like corrosion products. He explained that polished aluminum has little corrosion resistance because aluminum is very active, so once it is left uncoated it can corrode in this way. His practical advice was that the metal should be anodized or clear coated if corrosion resistance is needed. The exchange suggests that aggressive cleaning may remove some buildup, but it will not solve the underlying issue, and the damage may already be corrosion rather than surface contamination.
Q. I have polished aluminum rims with no clearcoat. There is a white crusty stuff which I believe is salt developing on the aluminum. I drove one time after they salted the roads for snow. I used a metal cleaner and an abrasive sponge which did take some but not all of it off. This took hours per rim. Is there a stronger metal cleaner I can use or do you have any other recommendations?
Jevan Fazekas
– Easton, Pennsylvania, USA
2003
A. You are not going to like this, Jevan, but it’s not salt. Aluminum will pit and corrode with salt-like corrosion products. Polished aluminum has no corrosion resistance since aluminum is a very active metal. It must be either anodized or clear coated or it will corrode like this.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2003
Q. A reader ask about cleaning the crusty deposits off aluminium wheels. Response was it is an oxide. Okay I get that; now I want to know how best to clean it off and stop the action.
Bill Shimer
– Deerfield, Illinois, USA
April 11, 2012
A. Hi, Bill.
Yes, you are right that it is an oxide. The point, which I can’t be sure whether you got or not, is that it’s not some deposit “on” the wheel, but a deposit formed “from” the material of the wheel. The aluminum itself is damaged; in the spots and pits, small amounts of it are gone.
Other readers may have tips, but I think what you need to do is mechanically polish the deposits away (the crustiness is probably “volcanic” eruptions around each pit) or the whole wheel, then paint them with a corrosion retarding paint. After polishing them you could just clearcoat them, but that doesn’t offer much corrosion resistance, so you probably would be in the same spot again rather soon.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
April 12, 2012