Topic: Unpolish (is that even a word?)

I'm not in the metalworking trade by day, so I hope I'm not overstepping forum boundaries by posting a newbie question...

I recently purchased a set of tig welded aluminum valve covers for a project that I work on in my spare time. The covers came highly polished (like a mirror), but after mounting them on my engine I decided that they were a bit too flashy for my taste. So my question: What do I do to "unpolish", or dull them up a bit? I was going to try taking a bit of steel wool to them, but I don't want to risk ruining them by experimenting, and I haven't been able to find any techniques online.

Any help would be appreciated!



Re: Unpolish (is that even a word?)

You can etch aluminum in most strong alkali or acid solutions. I've heard of people using drain cleaner (aka Drano) to clean aluminum, leaving it with a smooth, matte finish. Of course, I've recommend that you do this on some sample pieces first. Also, you will probably need to protect the finished surface from further oxidation by applying some form of a coating, like a high-temp clear enamel or lacquer.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer


Sanford, NC


Re: Unpolish (is that even a word?)


You can have a try for the magnetic grinding machine. This machine can remove the shining layer, and make your part for matte polishing.

Jeddy Huang


Tonzze Machinery Factory

Jeddy Huang


Deburring & Polishing Machine