I recently purchased a pile of antique lights and after going through the pile I found a few I liked for my own projects. I decided to play with restoring a couple of the leftovers to resell and pass on to other collectors. I had a couple key things I wanted to accomplish with this project. I wanted to bring the "bling" back to the lights, without taking away from their "age". Most of these antique lights had brass buckets and trim rings with either cast iron or steel bases. This particular light I believed to be from an early 1900's fire truck. From what I could gather it was used as a spotlight on the corner or side of the truck. It has a mounting base that is made of cast iron and is pretty rusty, but the cradle the light sat in was copper. The light itself is brass with a silver reflective inner surface and a glass lens. Brass and Copper don't rust like steel or cast iron, but they DO still corrode. Brass and copper parts usually have a gray-ish corrosive coating, sometimes with hints of green on the surface. When they've been sitting as long as this light had been, you can't just use a degreaser or cleaner to cut through the corrosion. It now has a hard coating over the base metal and it has to be abraded to be removed.
On this light the corrosion was pretty bad so I decided to blow the light apart and attack each part separately. It's a good idea when working on fragile, antique parts like this to take your time and start with the least aggressive cleaning methods first and work your way up until you find one that's the most effective without damaging the metal. Brass and Copper are pretty soft metals and they can be worn away and damaged easily. This means you don't want to just go at the surface with an angle grinder and a flap disc! Will it remove the corrosion in a hurry? Yes.. but it'll also remove a LOT of the metal QUICK and you'll be left with a pile of dust. I started by trying some Emery buffing compound to cut through the corrosion on a 1/2 hp buff motor. It worked, but took a lot of time,force and put a lot of heat into the parts to even begin to cut through the hard core of the corrosion.
I decided to jump to a Palm DA sander and some 400 grit sand paper. Now I was on the right track! It took the corrosion off a lot quicker, but the paper clogged pretty quickly. I decided to move up to 180 grit paper and light pressure on the DA sander. This worked beautifully and in no time all of my parts were at least their original color again. From here I worked my way down with the DA and progressively finer grit sandpaper until most of the scratches were out. Normally I would hand sand something from here and spend hours rubbing it out with SimiChrome or Autosol. The secret I found to speeding this process up was by taking some Norton Dry Ice DA Sandpaper in 1000-1500 grit and going over the parts. This gave the parts a nice shine and only required a couple passes by hand with the metal polish to get a brilliant shine on the parts.
I didn't go nuts taking every scratch and imperfection out of the light because I wanted to leave some character to the light so that it may proudly show its age without looking like it was a lost cause! This entire project from start to finish was done in an afternoon and was extremely rewarding considering the transformation only took a DA sander, sandpaper, and some metal polish. My only problem now is that it looks so dang cool I want to keep it and repurpose it into a lamp for my house!