Jason,
Polished brass does have a certain richness to it that doesn't seem to survive a clearcoat. It still shines . . . but . . . it's not the same is it?
I am a sculptor and work a lot in aluminum, copper, and stainless. (Stainless has it's own laws: it is so difficult to work, and to polish, that after you do it once, it leaves you alone forever. It extracts it's pound of flesh all at once, instead of over time.)
I use a wax on the copper and aluminum that museums use. So far it seems to prevent oxidation if applied once a year. None of my stuff is out in the weather. I don't know about that; probably a whole different game.
The company that I get it from also sells polishing supplies, so I would probably be in violation of the terms of use of this forum to post their name here. Caswell is the best place to buy polishing supplies anyway, but if you want the name of the wax supplier you can send me an e-mail at
richards@well.com, and I will give it to you.
Richard