I like putting them in an electric drill and spinning them against the wire wheel on my bench grinder...they get a nice "burnished" look...then you can use as-is or blacken or paint or whatever... Of course, the threads then have to be cleaned and unless you have a real big chuck, you'll have to do it by hand...If your using the wire wheel on, say, four bolts, one of them will inevitably fly across the shop...that's when the goggles come in real handy!