Sand-blasting

Abrasive blasting is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface, or remove surface contaminants. A pressurized fluid, typically compressed air, or a centrifugal wheel is used to propel the blasting material (often called the media). The first abrasive blasting process was patented by Benjamin Chew Tilghman on 18 October 1870.

There are several variants of the process, using various media; some are highly abrasive, whereas others are milder. The most abrasive are shot blasting (with metal shot) and sandblasting (with sand). Moderately abrasive variants include glass bead blasting (with glass beads) and media blasting with ground-up plastic stock or walnut shells and corncobs. A mild version is sodablasting (with baking soda). In addition, there are alternatives that are barely abrasive or nonabrasive, such as ice blasting and dry-ice blasting.

One of the original pioneers of the wet abrasive (vapourmatting) process was Norman Ashworth who found the advantages of using a wet process a strong alternative to blasting with silica sand—which is banned in many countries. Open blasting with other abrasive media that do not produce hazardous dust is generally accepted as industry standard.

Common features include: the ability to use extremely fine or coarse media with densities ranging from plastic to steel, the ability to use hot water and soap to allow simultaneous degreasing and blasting, elimination of dust—so silicacious materials can be used without worry, hazardous material or waste can be removed without danger—e.g., removal of asbestos, radioactive, or other poisonous products from components and structures leading to effective decontamination.

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