How to Polish Aluminum Components
Whether they're on a car, truck or even a motorcycle, aluminum parts that have been polished to a mirror-like finish are beautiful to look at and contribute greatly to the overall appearance of the vehicle. If you have some aluminum parts that you want polished, you can always take them to a professional shop to complete the job, but that could potentially cost hundreds of dollars. Aluminum polishing can be done by the inexperienced with the right tools and knowledge.
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Things You'll Need
- Electric drill or high-speed buffer
- Air-powered die grinder
- Ear muffs
- Respirator
- 5-inch discs for a power drill, 40-, 80- and 180-grit
- Wet sandpaper, 220-, 320-, 400- and 600-grit
- Foam pad
- Conical-shaped sandpaper drums
- 2 polishing wheels, 6-inch
- Polishing rouge (rubbing compound and polishing compound)
Instructions
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Remove the aluminum part if it is installed on something. This applies to parts like water pumps and valve covers that are bolted to the engine. Polishing relies on high-speed sanding and grinding tools and can be quite messy.
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Clamp the part you want to polish in a bench vise or fasten it to a surface so that it can't move around during the sanding process. If the part is very rough with casting marks that you want to remove, sand it with the 40-grit, 5-inch sanding disc and the electric drill. Carefully remove the casting marks and rough edges. Aluminum is relatively soft, so try not to gouge the metal excessively. If the part is not that rough of a casting, you can start with the 80-grit sanding disc.
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Rinse off the aluminum with water and dry it. Move up to the 80-grit, 5-inch sanding disc, sanding the entire part and then finishing with the 180-grit disc. At this point, you should be removing any scratches on the surface. For harder to reach areas, use a conical sanding attachment and an air-powered, high-speed die grinder or the electric drill. Rinse the aluminum periodically with water to check your progress.
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Wet sand the surface of the aluminum with 120-, 180-, 240-, 320-, 420- and finally 600-grit wet sandpaper. Keep the surface constantly wet by continually dipping the sandpaper in a tray of water or wetting the aluminum. Use a foam sanding block to get a flatter sanding surface. This process may take several hours to complete.
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Use the electric drill or a high-speed buffer and a new, 6-inch polishing pad to begin the final polishing process. Apply the polishing rouge to the buffer by holding the rouge against the pad and then turning it on so that it spins against the rouge. Slowly polish the part one section at a time. Do not press too hard, and stop frequently to check your work. Apply more rouge to the buffer as needed. For hard to reach areas, use a small felt polishing cone, which are available in a variety of shapes and sizes.
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Install a new buffing pad and finish the final polishing with the polishing compound, which is a finer compound than the previously used rouge and should bring out the final, mirror-like shine. If there are any remaining scratches that are revealed in the polishing, you can go back to the wet sandpaper and repeat the process of sanding followed by a final polish.
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