Sandblast media are abrasive particles which, when combined with a stream of pressurized air or water, are used to change the properties of a surface. Sandblast media can be a collection of silica, ground corn cobs, walnut shells, garnet, copper slag, cut wire and a wide variety of other materials.
Sandblasting originally made use of silica particles exclusively, but as research uncovered health risks associated with long-term exposure to the dust created by silica blasting, alternative media were developed. These media, while minimizing health risks, were also discovered to outperform silica media in some applications. For example, the development of shot peening equipment allowed for the speedy and efficient peening, or strain hardening, of large areas of metal surfaces, a process that would have been impossible using silica media. Crushed walnut shells were also developed as blasting media and were discovered to create smaller amounts of dust during the treatment process. Soda blasting equipment, which uses bicarbonate of soda for blasting media, became popular for the same reason. Even more varieties of blast media are utilized in grit blasters and shot blasters.
All media blasting treatments work according to the same, basic concept: small particles moving at high speeds collide with surface particles and dislodge them. Beyond this commonality, though, blasting techniques vary dramatically in terms of method and their intended purpose. One use, for example, could be to remove impurities from a surface in advance of paint reapplication. Such sandblasting projects are usually intended to create the smoothest, most paint-ready surface possible. Glass etching, on the other hand, can be performed with entirely different blast media and may leave the surface rough and clouded. Different effects will be achieved in the blasting process depending on what kind of blast media is used. Aluminum oxide, for example, is used for cutting through metals and is prized because it can be easily reused. Corn cobs are often used when a surface is likely to be damaged by harsher media. The rest of the variety of basting media ranges for the super-coarse and hard to the super-fine and soft; the whole range is necessary to accommodate the equally wide range of media blasting applications.