The best way to polish aluminum is to buff it with a paste made from cream of tartar and a little warm water. This non-toxic, gentle solution removes tarnish without scratching soft aluminum finishes.
Before polishing aluminum objects or surfaces, wash them with a gentle detergent or soap, and rinse well with plenty of warm water. This removes any gritty residue that could scratch the finish during the polishing process. Next, pour some cream of tartar into a small container, and mix it with just enough warm water to form a paste. Cream of tartar is a mild, acidic cleanser that works well on aluminum by chemically removing spots and physically shining the surface. Rub the cream of tartar evenly over the aluminum surface with a clean, soft cloth, using small circular motions. If the object has hard-to-reach crevices, use a soft brush to work the polish into the recessed areas. Continue buffing in small circles to dry the paste and remove the cream-of-tartar residue. This action finishes shining the piece.
Do not use ammonia-based cleaners or baking soda for polishing aluminum. These alkaline solutions discolor and spot aluminum surfaces. Likewise, avoid polishes intended for other metals, such as silver, copper or brass, because those polishes are likely to scratch softer aluminum surfaces.