It is possible to make a dull aluminum surface into a gleaming mirror with the correct tools and some patience. Follow the procedure outlined below to polish an aluminum mirror into a chrome-like reflective finish.
Step 1 - Clean the Aluminum
Remove debris, dust and any corroded flakes from the aluminum by washing it in hot water and a mild dish detergent. Rinse the aluminum piece thoroughly in hot then cool water and dry off with a linen towel.
Step 2 - Check for Anodization
If the aluminum has a dull, brushed finish, it has probably been anodized. You need to remove the anodizing compound before polishing the aluminum. Apply a thick coat of spray oven cleaner to the entire aluminum piece. Use this cleaner in a well-ventilated area. Leave it on for at least 10 minutes or until the cleaner turns dark brown. Use a clean linen towel to remove the oven cleaner, rubbing in a circle to lift off the foam. Rinse off the remaining oven cleaner in warm water and towel-dry with another clean towel. The aluminum will look very dull, but this is its normal appearance when not anodized.
Step 3 - Bathe the Aluminum Piece with Paint Thinner
Pour a generous amount of paint thinner onto a clean linen towel and wipe over the entire surface of the aluminum piece. Dampen another clean towel and wipe off the paint thinner residue from the metal. Leave the aluminum surface wet.
Step 4 - Sand the Aluminum to Smooth the Surface
Starting with a dampened piece of 320-grit paper and working up through 400, 800, 1200, 1600 and 2000-grit, polish the aluminum to smooth the jagged metal surface so it becomes more reflective. Move the sandpaper in small circles all over the aluminum surface. Wet the sandpaper again as it dries. Each successive sanding will remove the scratches from the previous paper. The aluminum will become as reflective as a polished shoe by the 2000-grit sanding.
Step 5 - Apply Brown Polishing Compound
With a metal-buffing pad, apply brown tripoli polishing compound, also called cutting compound, to the aluminum. Work it in with a circular motion over a tiny area, then move to the next area. Blend in the brown polishing compound when you have covered the aluminum piece, working in large circles.
Step 6 - Apply Ruby-Rouge Polishing Compound
To a clean metal-buffing pad, add ruby-rouge polishing compound and buff it intensely into the aluminum. Continue buffing with the ruby-rouge compound until you reach the chrome-like reflective finish of a true mirror. Switch to a clean buffing pad when the first one becomes black.
Step 7 - Smooth Off Fingerprints with a Soft Cloth
Use either a clean dry chamois or a soft flannel cloth to wipe off any smudges or fingerprints made during the polishing process.
Sanding aluminum and then polishing with the cutting compounds yields a dazzling, unbreakable mirror finish that will not glaze or crack like glass.