Historically, the material used for artificial sandblasting was sand that had been sieved to a uniform size. In the early 1900s, it was initially assumed that sharp-edged grains provided the best performance, though this was later demonstrated not to be correct. Other materials for sandblasting have been developed instead of sand; including carborundum grit, steel shots, copper slag, powdered slag, glass beads, metal pellets, dry ice, garnet, powdered abrasives of various grades, and even ground coconut shells, corncobs, walnut shells, and baking soda (soda blasting).