Introduction: Polish Aluminum Sheet Metal to Mirror Finish
When I turned my TARDIS model into an infinity box, I used some pieces of polished aluminum for some of my mirrors. I polished that aluminum myself, but I didn't polish the whole sheet to a mirror finish. In the picture you can see the other side of that sheet, which got scratched up while I polished the first side. Back to the first side, I show how the original finish was of the sheet, and then how much I polished it to. Let's start polishing the scratched up side so I can show the process that I followed.
If you want to see the video version of this Instructable, you can view that here: https://youtu.be/STwX_1VzggQ
Step 1: Optional First Step
I first tried using a couple metal polishing products, they worked but had a very strong odor. After some research I decided to try using WD40. To get rid of the scratches I'll start by sanding it with some fine grits of sand paper, first 1000 grit. For the first side I didn't do this part, and generally isn't necessary. But it does help to get rid of scratches that are in the metal before the polishing starts. Don't forget to spray a layer of WD40 before each of the sanding and polishing steps. You could probably do this by hand, but it would be a lot more work.
For this demonstration I won't be polishing the entire side, just the center portion. If you want to polish all of the way to the edges, just keep in mind that you will likely also sand whatever work surface that you are using. And again, if the metal sheet that you're polishing is in relatively good condition, you will be just fine to skip the sandpaper steps.
Step 2: Clean, and Repeat
After each of the sanding steps, wipe off the residue with a microfiber cloth. The one I'm using is designed for use on polished metals. After the sanding step, the surface is grey and not shiny like it used to be. It will be like this after each of these sanding steps. Just add more WD40 and move on to the next grit. I'll repeat these steps up to 3000 grit.
Step 3: Start Buffing
Next I'll move on to the buffing pads. This is actually where I started out on the first side, and got great results. Again, ONLY use the sandpaper first if the surface is already in rough shape.
For the buffing pads, just follow the same steps. Apply the WD40, then use the buffing pads the same as you would sandpaper, wiping them with the microfiber cloth after between each buffing pad. The buffing pads that I used are color coded for how course or fine they are. I cannot tell what the grit is for each one just by feeling them or looking at them. The package they came in has them listed in order.
Step 4: Go Through Each of the Buffing Pads
It's hard to tell, but even after finishing with the first buffing pad there is a bit of reflection showing through. With each buffing pad, more and more reflection shows through. I have pictures showing the progress from each buffing pad.
Step 5: Second Pass of the Buffing Pads
After going through each of the buffing pads once, there is obviously some reflection, though it looks hazy. This is because of the sanding steps that I did at first. But more buffing will help to clear that up. I start back with the first buffing pad and go through each of the steps again.
After the second pass through the buffing pads, my batteries are ready to be recharged, so I stop for the day, clean the buffing pads, charge my batteries. Comparing this side to the first side shows that I have a bit more polishing to go before it gets to a good mirror finish. You can also see that the first side is getting scratched up with the whole process. This is important to remember and keep in mind for your own project.
Step 6: Extra Polishing With Microfiber Polishing Cloth
When I got back to the polishing, I started with the first buffing pad and went through the same steps. But this time I added an extra step. After wiping away the reside I used my microfiber cloth to buff the surface. I did this after each use of the buffing pads. This was a step I forgot to do earlier, and it seems to help with the polishing process.
Step 7: Repeat As Needed
Once I finish going through each of the buffing pads again, I compare it to the first side. You can repeat the process as many times as you like to get the level of finish that you want.
I hope this was helpful! If you have any advice on ways to improve the results or make the process easier please leave a comment.