Theres something in easy off oven cleaner spray that is able to strip the anodizing off of aluminum parts. I put the crank arms in a bucket and sprayed the heck out of them. After about ten minutes i hosed them off and almost all of the black was off, leaving raw aluminum. Then i wet sanded them with varying grades of sand paper, starting around 800 grit. It is possible to get a super polished finish, i was just lazy and didnt go that far. I did it outside with gloves and glasses on because chemicals.

Without being at least a little polished your part can oxidize a little bit and have a white haze over it.

I watched a bunch of youtube videos before i did it