As I recall, anodizing is done by running current through the piece in a basic (pH approx 10 or more) solution and adding a dye to the solution. This forms a surface of aluminum oxide which traps the dye in the oxide and a lot of colors can be used or not. Aluminum will dissolve in either acid or basic solutions but the anodized surface is an oxide which would normally dissolve in acid. I have not tried this but if you use any acid it should be a mild acid and I would try buffing with a cloth buffer dipped in white vinegar which is a dilute form of acetic acid and is mild enough to not dissolve clothes or other metals near the splash/spray. Muriatic acid (HCl) would be too strong and would make holes in your clothing, not to mention the need for eye protection! I did work at a plant that did anodizing but it was the finished surface and we did not try to remove it. As I said I have not tried this but powdered aluminum oxide (alumina) is a form of abrasive itself so the combination of mild acid and surface buffing may do the trick. Let us/me know if this actually works! I offer no guarantee other than the usual chemical principle that oxides are basic and acids dissolve bases but aluminum is unusual in that it reacts easily with acids and bases (amphoteric!). Since the salt formed will be aluminum acetate and all acetates dissolve in water, cleanup is easy with water wash/wipe.

Don Shillady
Retired Scientist/teen rodder