I first got this idea when I decided I didn't like the chrome shine of removable split shot. At first I tried painting the split shot but that was labor intensive and the paint came off. I don't know why I thought of gun bluing but it works much better than paint. Now, when I want to dull-down something, in this case, dumbbell eyes for a damselfly nymph I'm tying, I put the eyes in a dixie cup of gun bluing, let them sit for an hour, drain out the bluing and dry the eyes on a paper towel. It works like a charm. I sold the idea as a tip to Sports Afield long, long ago so you older guys may remember seeing it in The Almanac section. Yes, you can buy black dumbbell eyes but I didn't have any but instead have an overabundance of chrome jobs. Remember, the idea was originally for chrome, removable split shot and they don't make those in black. Just a FYI.