I didn't think to take a good picture before I started; I only have an older picture I took for a different reason:
That picture doesn't really show the extent of the corrosion. The sponge area was covered with whitish corrosion byproducts, and it had a death grip on the die-cast zinc (AKA: pot metal). I normally remove corrosion byproducts with Bar Keepers Friend (main active ingredient: oxalic acid). For example, it removes similar looking corrosion byproducts from aluminum alloy wheels fairly quickly, but it wasn't having much of an effect on this stuff. Steel wool and a steel wire brush were pretty much ineffective as well. So I gave it a 24-hour bath in a solution of water and pure oxalic acid, and that fixed its wagon.
Next I needed to remove the powder coating. I'd already removed all of the powder coating that was loose due to being separated from the metal by corrosion, but the rest of it wasn't going to come off easily. Then I remembered that I have some Goof Off Graffiti Remover, and a long time ago I discovered that it melts through some types of plastic (Lexan [polycarbonate] for example). Given that powder coating is just a type of plastic, I gave it a try, and it did indeed melt it. However, it evaporates too quickly to let it soak long enough to completely melt through it, so I had to spray some on and scrub with a wire brush, and repeat until it was all gone:
You can see the damage from the corrosion in and around the sponge area, but the damage isn't even close to being deep enough to cause any structural issues. The rest of the metal was pristine:
Here it is with a couple of coats of primer:
I want to finish it with Rust-Oleum textured black paint, which does a pretty good job of approximating the appearance of typical textured powder coating, but of course, no place in town had it. They had plenty of cans of various types of Rust-Oleum, but not the textured type I was looking for. So I ordered some online yesterday. I'll post a picture when it's finished and reassembled.
I've never seen another Metcal workstand like this. I'm guessing it's older than the common WS4 workstand like we used at the PCB factory I worked at in the late 1990s:
I like it because it's all metal. The WS4 is mostly metal, but the insert that you place the handpiece in is plastic, and those can break (there were a few broken ones at work).