I used to do a lot of champlive work with resins. It was all ground
and then re-polished. The only ‘trick’ I found was (A) I built
myself a slow-speed flat lap machine, and (B) lots, and lots of
patience. You can polish it with zam, with a couple of things in
mind. First, your sanding must be immaculate. Normally, on metal, you
can go from 220, straight up to 400, then hop onto the buffs right
from there. Not a hope with resin. The scratches won’t ‘flow’ closed.
They’ll just stay there, lurking, until you go to do a final polish,
and then discover that you’re going to have to go all the way back
down to 320 grit to get them out.
So, sand with 320, then cross that with 400, cross that with 600,
and then start buffing. I tended to use felt buffs. (but then
again, I was doing flat surfaces.) The little teeny felt buffs that
are combo’d with felt inside ring spikes seemed to work pretty well:
too small to build much heat.
First compound was usually English Tripoli. (Bought in Hatton Garden.
Dunno what the difference is between the tripoli here in the states,
but there is a slight difference.)
Follow that up with a soft 3-4" buff with zam on it, and final
polish with a soft flannel buff with nothing at all on it. I have
some specialized plastic compounds that I played with towards the end
of when I was doing that sort of work. Some of them worked well,
some, not so much. The best of them was something I got from Vigor
for polishing plastic watch crystals. (Don’t remember the name, but
it’s a small, pumice colored stick. (No, not made pumice, just that
sort of dirty brown color.))
The biggest issue is heat. If you let the piece heat up, the resin
will melt and smear, and then you’re toast. Keep the buffs slow and
cool. Make sure all of your coarser scratches are out before you
switch to the next higher grade of paper. Resin has no forgiveness.