Jay, I've been using plain, old visqueen, or LDPE (low density polyethyline), for wet working, and any flexible fabric for dry...like a light canvas, unless the gold is superfine flour when working dry...then you need a watertight material like heavy visqueen, or a rubberized fabric, so the flour doesn't go through. When working wet, with a 6mil diaphragm you get about 3 hours of use before the plastic gets holes in it. But, it's cheap, and easily replaced.
What material is the matting?
Jay, I've been using plain, old visqueen, or LDPE (low density polyethyline), for wet working, and any flexible fabric for dry...like a light canvas, unless the gold is superfine flour when working dry...then you need a watertight material like heavy visqueen, or a rubberized fabric, so the flour doesn't go through. When working wet, with a 6mil diaphragm you get about 3 hours of use before the plastic gets holes in it. But, it's cheap, and easily replaced.