Aluminium is extremely reactive, as it combines with oxygen to form aluminium oxide or aluminium rust. As this oxide builds up, it can form a black stain on the aluminium, discolouring it. This black coating can rub off on clothing, counter tops and other surfaces and makes the aluminium look bad. Regularly cleaning aluminium will keep black stains from reforming.
Mix 1.15 L (1 qt.) water with 54 ml (3 tbsp) each of cream of tartar and vinegar in an aluminium pan. If you are not cleaning a pan, mix the ingredients in a bucket.
Boil the solution in an uncovered aluminium pot for 10 minutes. If you are not cleaning a pot, rub the solution over whatever aluminium surface you wish to clean and allow it to sit for 10 minutes.
Fill a small bucket with water and about 6 ml (2 tsp) of mild detergent. Dump out the pot if you are cleaning one. Wet a plastic scouring pad in the soapy water and scrub the aluminium surface vigorously. If the stain is still there, cover it with the tartar, vinegar and water again and scour it once more.