Silicon Carbide is the hardest of the abrasive blasting media. On the Mohs hardness scale, Silicon Carbide has a hardness of 9.5 (diamond is a 10). While this mineral does occur naturally, it is rare and most is manufactured synthetically using an Acheson furnace.
Silicon Carbide is sometimes referred to as ‘black sand’ but contains no silica. The hardness of this media makes it ideal for etching on surfaces such as glass and stone. Larger grit sizes can result in extremely heavy, rough and deeply etched surfaces while the smaller grit sizes can produce a very fine and ‘frosted’ etched surface. Silicon Carbide has a very high/fast working speed and is typically used in a blasting cabinet.
Relative to some other abrasive blasting media, Silicon Carbide does break down more quickly. Because of the higher cost of the media and the high fracture rate of the particles, this media is generally used for specialty applications or in areas where Aluminum Oxide (as a more general purpose abrasive media) is not aggressive enough.