Well-polished aluminum can look like chrome but it takes time, effort and patience to get the glossy mirror finish. You will need to work methodically to get this shiny finish. The most important thing to keep in mind when polishing aluminum is that the smoother you get the surface, the more mirror-like it will be when you are finished.
Wash the aluminum using a liquid dish detergent. This will remove any debris, which makes polishing the aluminum easier. Allow it to dry completely.
Sand the aluminum using 320 grit sand paper. Wet the sandpaper and the aluminum and begin sanding. This is called wet sanding. Take your time and make sure that you sand the entire surface.
Continue sanding using the same method with sandpaper of higher grit. For example, use 400 grit, then 600 grit followed by 800 grit, then 1200 grit and finally 2000 grit. With each new grit, you should remove all the marks from the previous grit. By the time you get to the 2000 grit, the aluminum will be very smooth.
Buff the aluminum using a buffing pad and brown cutting compound. Use circular motions. After you buff using the brown cutting compound, rebuff using a clean buffing pad and rouge cutting compound.
Wipe the aluminum off with a flannel or chamois cloth. This will remove fingerprints and smudges.
Wear gloves, a respirator and protective eye goggles or glasses when you polish aluminum.
Use an orbital sander to sand and buff if you are working with a large piece of aluminum.