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Polishing Metal to a Mirror Finish
One of the best things about metal is its versatility. It is strong, can be worked into almost anything, and it can be polished up to a beautiful mirror finish. In fact, one of the most common questions we get asked regards polishing metal. Specifically, people want to know: How difficult is it to polish metal? And can I polish metal myself?
In short, the answer is yes! All metal can be polished. Though some do polish easier than others. But some good news is that there are plenty of methods and tools to polish metals.
Why Polish Metal?
Outside of the fact that each metal has its own unique and beautiful color, there are plenty of reasons for polishing and sanding material. Specifically, polishing metal acts as a sealant. Because of this, it is more resistant to oxidation or chemical corrosion. Also, it makes the material easier to clean and increases wear resistance. If you need your piece to resist friction, polishing metal will do the trick.
What Tools Do I Need to Polish Metal?
Power tools are magic when it comes to polishing. Drills, Dremel’s, rotary buffers, rotary sanders, and the like, will make your life so much easier. Sandpaper and buffing attachments/wheels are available for all these tools and are typically worth the investment.
That being said, power tools aren’t required. Archaeological evidence shows that humans have been polishing metal since we figured out how to use metal about 5,000 years ago. Power tools have only become commonplace in metal polishing within the last hundred years. Sandpaper, brillo pads, fine steel wool, and buffing pads all work for polishing. However, it will be slower than using power tools.
Metal polishes are the last “tool” you’ll need. Technically, polish isn’t necessary either. Soapy water, WD-40, and even toothpaste can be used to polish metals, but actual polishes work a lot better and a lot faster.
There are lots of different methods and tools available to polish metals to a mirror. It’s very similar from metal to metal, but our expert Tyler Elmore (Skills and Trade) prefers sanding to a very high grit and using a polishing compound.
Here is a list of his tools:
- Multiple grades of sandpaper running from 220 grit to 5000 grit
- Finishing pads
- Lubricant, Polish, and sealant
- Blue shop towels
- A drill and the pads needed to hook the sandpaper polishing attachment to it
Metal Polishing Techniques
Sanding Metal to a Mirror Finish
It’s actually really straightforward. Metal shines naturally, but over time it oxidizes and gets scratches. The oxidization and small valleys made by scratches prevent light from reflecting, and thus muck up your shine. By polishing, you are grinding off the oxidization and a very thin layer of the metal itself. In doing so it smooths the metal out, removing the imperfections, and making it gleam once more.
You start with a coarse grit sandpaper, somewhere around 40 to 80 grit. Then just sand the metal to be polished. Make sure any big scratches are out. Then, sand it again with a finer sandpaper, somewhere around 100 or 160 grit. Sand everything evenly again. Sand it again a third time with finer grit paper, around 200. Then you just keep repeating that step over and over with finer papers. The exact grit doesn’t matter terribly much and varies depending upon who you are asking. Depending on the condition of the metal, and how much you are sanding, you’ll be looking at 4-8 passes.
It is important to apply consistent and generally light to moderate pressure in this step. If you push too hard, you grind away too much material and create more divots. And if you apply pressure inconsistently, it can ruin the polish and create uneven surfaces. Furthermore, it is important to find a balance in speed. Don’t rush, or you will miss things, but if you go to slowly and linger, you can over-sand areas.
Buffing and Polishing Metal
Eventually you’ll be using sandpaper somewhere around 2,000 to 4,000 grit sandpaper. Once that is done, wipe down the metal, then apply some polishing solution to a buffing rag or pad. With medium pressure, buff the metal. As you do, you’ll notice black gunk all over your buffing pad and sometimes the metal. This is mostly the metal oxide wiping off.
Wipe it down again with a clean microfiber cloth. If it looks good, call it there! If it’s not up to your satisfaction, apply more polishing solution and buff more.
Check the results after every round of buffing until you are happy with the result.
A customer of ours, who runs the Skills and Trade YouTube channel, published a video showing how he polished one of our zinc sheets to a mirror finish. And oh boy does that sheet shine when he’s finished with it! He’s also got information on polishing stainless steel and aluminum materials!
How Do Metal Polishes Work?
Polish is both a lubricant and mild abrasive. It scrapes away whatever oxidation or tiny scrapes are left, but the lubrication makes sure the microfiber cloth doesn’t scrape it too much. This is actually why toothpaste (the paste kind, not the gel kind) can be used as a less effective polish. It’s slightly abrasive and a lubricant.
Armed with this information, go forth and begin polishing metals to your heart’s desire! If you’ve got any pieces you want to share with us, please do so!