Bicycle Mechanics - aluminum corrosion

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merlinextraligh
10-03-06, 11:32 AM
The crankset on my Paramount has spots on it that appear to be the Aluminum corroding. Any ideas on how to remove the spots? It's only a cosmetic problem, so any solution needs to end up not damaging the finish to the crank.

http://i72.photobucket.com/albums/i165/bobstewart/paramount1.jpg

humble_biker
10-03-06, 12:04 PM
polish them with a mild car wax and non-abrasive chamios, rag, sponge, etc...
mlts22
10-03-06, 02:16 PM
Ammonia gets aluminum corrosion off pretty well. Just make sure to use eye protection and have good ventilation.

CastIron
10-03-06, 02:35 PM
The crank likely has a clearcoat or clear anodizing over it. Tough stuff, but hell to pay when it starts to go. The easier way is to pull the crank and use aircraft stripper and THEN set about polishing the crank.
Grand Bois
10-03-06, 07:26 PM
The crank likely has a clearcoat or clear anodizing over it. Tough stuff, but hell to pay when it starts to go. The easier way is to pull the crank and use aircraft stripper and THEN set about polishing the crank.

Aircraft stripper removes anodizing?
gmcttr
10-03-06, 08:45 PM
Aircraft stripper removes anodizing?

No, but it will remove clearcoat (a paint product).

If it is bare aluminum, use "Mother's Mag and Aluminum Polish". It is sold at auto stores.
mlts22
10-03-06, 09:26 PM
Just buy these -- http://tinyurl.com/poe5b

I'm pretty sure this will cure your crank anodizing issues.

But seriously, I'm wondering if sandblasting with walnut shells will remove the clear anodizing (if it is anodizing rather than a paint or lacquer coat), allowing you to use previously mentioned products. It may be a bit expensive though.
gmcttr
10-03-06, 09:46 PM
Anodizing is a process that converts the surface layer to aluminun oxide. Do not think of it as a removeable layer short off sanding/grinding and repolishing.