plating, anodizing, & finishing Q&As since 1989
Finishing a rough finished, flat casted bronze medal
my son is being inducted into an engineering fraternity and one of the requirements is to finish a flat casted, rough finished bronze medallion or "bent". it is about 2" by 4" and we are clueless and how to go about putting a nice finish on it without ruining it. I thought perhaps a Dremel [affil link] would be the only thing we could use on such a small piece but I don't know if they make attachments that would give it a finished look. any guidance would be greatly appreciated.dan lyons
- so. bound brook, new jersey, u.s.a.
The general principle is that you get a smooth shiny mirror surface by buffing with a soft wheel and fine buffing compound--but that to buff a rough cast surface to a mirror finish like that with a soft wheel and fine buffing compounds would take many eternities. So, what you do is you sand the rough surface with course Sandpaper [affil. link] until no lines are left other than those put there by the rough sandpaper. Then you sand with medium sandpaper until no lines are left from the course. Then you sand with fine paper. Then you polish with a heavy wheel and polishing compound, then you buff it with a soft wheel and fine buffing compound. I can't give you the exact number of progressive steps, or the exact grit sizes, but that's how it's done. Yes, it does take forever, but at least that's only one eternity instead of many.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey