Grit size and type are important when sandcarving glass. For best all-around results, silicon carbide grit in a 180 mesh size is recommended. To do fine detail, and for shading purposes, 220 mesh or finer works well. Other abrasives (such as aluminum oxide) can also be used. Other considerations when sandcarving glass include blasting pressure, typically 25-35 psi, and blasting distance within a 4-6″ range.
—IKONICS Imaging
