I am confused
If you are going to polish the aluminum anyway, why not just polish off the coating???
I am thinking of stuff like Brasso
http://en.wikipedia.org/wiki/BrassoAlthough it does not mention it in the WIKI that you can use it for aluminum.
But, silica or kaolin or quartz powder plus a little rubbing should do the trick
the stuff below I just found as tricks for other kinds of removals
Stained Tub
Combine equal amounts of cream of tartar and baking soda with enough lemon juice to make a paste. Rub the mixture into the stain with your fingers or a soft cloth. Let sit for a half hour, then rinse well with water.
Scuffed Linoleum
Rub the spot with white toothpaste and a dry cloth or with an eraser. Or spray WD-40 on a towel and rub lightly, making sure to degrease the area afterward with liquid dishwashing soap and water.