Option 1: Powder Coat. I typically powdercoat (in clear) all the cartridges in the kits I sell. Powdercoating uses a baking process, however, which does discolor the brass and copper slightly (even when using low-temp powders). I'm still looking for a way to preserve the bright pink of freshly polished copper. So, for those who want the best color, I also offer:
Option 2: Brass Lacquer. StayBrite (tm) brass lacquer is formulated to adhere to brass and comes in spray cans. It is not quite as durable as powdercoat, but it is quick, easy, and doesn't discolor the brass or copper.
Regards,
Eric