I'm searching for a good material to use for masking while
sandblasting. I've found tape to be mostly unsatisfactory
I have always had excellent results with black electrical tape.
I cut off a length of it, stick it on a piece of glass, and use
an xacto knife or razor blade to cut the shape I want, then apply
it to the surface of the piece I want to texture. I also cover
the back of the piece with tape so the polished surface doesn't
get scratched, but I use a piece of tape larger than necessary so
I have something to hang onto. The whole thing is then taped
onto a piece of cardboard with any old tape. I'm careful to aim
the sandblaster away from the edge so it doesn't tend to lift up
the tape. I get a nice sharp line separating the polished
surface from the texture.
My problem has been that the sandblasted surface oxidizes in an
unpleasant way so it looks dirty. Silver can be cleaned
chemically but what do you do with a gold sandblasted surface
that just looks grungy?