Video tutorial on how to polish aluminum with a mirror finish. As an example I am using a piece of aluminum square stock, but I have used this method many times before on valve covers, other aluminum engine components, motorcycle parts, throttle bodies, carburetors, and wheels. I have recently refinished the lips of the wheels for my car. If you do plan on refinishing a set of wheels, this is a very work intensive job so be sure you are ready for something like that. And depending on how much time you are willing to spending will spending on the final finish.
- 400 grit wet/dry sandpaper
- 600 grit wet/dry sandpaper
- 1000 grit wet/dry sandpaper
- 1500 grit wet/dry sandpaper
- 2000 grit wet/dry sandpaper
- metal polish
- soft clean cloth
- backer pad (rubber or foam)
- rubber gloves
Step 1: Prep
You will need to remove any coating if any on whatever you are finishing. For my wheels, they did have a clear coat applies which needed to be stripped. Next ensure the item is clean, free of any dirt, grease, or debris which can jeopardize the polishing process.
Depending on the aluminum’s finish will depend on what sandpaper is needed to start out with. Any porous casting will need is a very coarse grit to cut down the high spots such as 160 grit. Considering we are working with aluminum, there are health risks associated with the dust, so to reduce the dust, use wet sanding. This aluminum is in good shape, I’ll use 400 grit in case the surface is mildly uneven. Pre-soak the sandpaper, wet the piece down, and then continue to sand. If it’s a flat piece, use a rubber backer, for contoured areas, a foam pad can be used as a backer instead which is what I used for polishing my wheels. This allows for even pressure across the surface, cutting down any high spots. Rinse the area continuously, along with the sandpaper, closely inspect the piece to ensure the material is smooth and any surface imperfects or the machined surface has been remove. Any deep marks most likely won’t be removed, but you can lessen the damaged area. Damaged areas can be filled in my welding, but if you don’t have the equipment someone will need to weld it for you,
Once satisfied, move up to 600 grit sandpaper. Considering almost all of the imperfections should have been smoothened out, we should only be focusing on the sanding marks and maybe any extremely light damage.
After you’re done with 600, you can then move up to 1000 grit.
Using the same process, move up to 1500 grit now.
And finally 2000 grit sandpaper.
Rinse the area thoroughly with water and ensure it is dry and using a clean cloth and your choice of metal polish, now we can work on the final shine. If you are working with a larger area you can use a machine polisher, drill with a buffing pad, rotary tool, etc. Apply the polish to a cloth and work it into the surface, depending on the polish, you may find it’ll turn black which is perfectly normal. Polish work times will vary and once it becomes harder to work with, wipe away and apply more polish if needed. Once you’re happy with the shine, apply a final coat of polish and finish up with a clean soft cloth.
Step 8: All Done!
The polished aluminum will last for a fairly long time, but this is still an exposed surface so it can suffer from water etching, staining, or any other exterior elements if it’s exposed to the weather. In some applications, you can apply a sealer or coating which will help protect it. For my wheels I have applied a nano coating which I plan to have more information on in a future video.