How about a little change of pace? While cleaning old bossman's humid and musty basement we found a huge 10 inch (so 25.4cm) wide FTD (F
elivery) insignia cast out of solid brass. Because of the humid conditions, the thing was caked with green tarnish/oxidation and looked in rough shape (unfortunately I didn't take a before pic).
I decided to see if I could restore it to at least showable condition. Watched a couple youtube videos on brass oxidation removal to determine if there was something that could make this process a little easier. Electrolysis was an option but out of the question as I didn't have the necessary equipment.
Saw one video where the guy used a poultice of salt and vinegar which seemed to do a decent job. Well, I didn't have any vinegar on hand but I did have CLR (a commercial C
ime & R
ust remover). No acetic acid in CLR but it does have oxalic and lactic acids so I figured acid is acid, right? Mixed up a batch of CLR + table salt, applied that and let it work for a few hours. It loosened up the oxidation a little bit so I let the brass sit in the stuff overnight. Rinsed it off the next day and scrubbed it with a nylon brush which got rid of almost all of the green. But there was some black stuff on it yet which didn't come off with anything water based. Tried paint thinner, nope still black. Stepped up to lacquer thinner and scrubbing and that worked. Apparently this thing was painted either originally or later.
The green and black were off, but there was still oxidation and a little paint or clear coat present. I didn't want to scratch the brass too much so I started with a nylon brush. No dice, not abrasive enough. Changed to a brass brush which did a little but was still ineffective. Reluctantly changed to a stainless steel brush and carefully scrubbed the back. It at least did something so I changed to the front and went to town. Way too much work by hand so I switched to a wire cup brush on the drill. Took quite a bit of brushing to remove the stains left from the other processes. Even used a 220 grit sandpaper to sand the rims and flat areas.
Leaving cleaned brass sit out in the humid summer air does cause oxidation to form again. So I ended up wire brushing the entire thing the other day, and since it looked fairly good again, I applied three coats of clear lacquer. Here's what it looks like:
Didn't really get a decent pic of it as the room was dark so I'll try to get a better one on Monday. It's much shiner in person than the picture. Yeah, there's still some dark discoloration around and inside the lettering on the edge. I just didn't have a small enough brush to fit inside those tight areas. At least it's protected from the elements now.