If you want to offer both brick and glass sandcarving, you should consider having two different sandcarving cabinets.
1) You do not want to mix brick fragments with glass fragments into your abrasive. The brick fragments will create pits in your glass.
2) You will want a coarser grit for bricks like a 120 mesh, and a finer grit like a 180 mesh for glass for the best appearance and production speed of your sandcarving.
-Darin Jones, IKONICS Imaging