Sandblasting is a process by which compressed air is used to propel an abrasive grit at very high speeds at an object in order to remove paint, corrosion or other debris from a surface. The grit is sometimes mixed with water, which helps control dust and keep down the dispersion of the grit and cleaned material. Silica, which is common sand is the most common type of sandblasting grit, but many other types are sometimes employed.
Silica sand is common sand. Its chemical name is silicon dioxide. Also known as quartz, silica is one of the most common minerals in the world. Silica sand is weathered quartz rock which is the main component of granite, and is the type of sand, found on most beaches and dunes all over the world. It is good for sand blasting because the particles are fairly uniform in size and the nearly microscopic sharp edges of the individual grains make it very effective for removing material from the object to be sandblasted.
Depending on the project, silica sand used as sandblasting grit may be coarse or very fine. Coarse sand is better at removing the surface detritus from the object being blasted, but fine sand is less destructive and leaves a smoother finish.
Almost any small-grained particle of uniform size can be used in abrasive blasting, as sandblasting is sometimes called. Depending on the desired amount of abrasiveness or the material being blasted, abrasives have varying degrees of hardness. Wood projects are often blasted with a material like crushed walnut shells or ground corn cobs which will remove paint and refresh the surface without damaging the underlying wood.
Soda is a type of sandblasting grit most commonly used in removing rust from metals. Soda used in abrasive blasting is actually bicarbonate of soda, or baking soda. It is abrasive enough to remove the rust without damaging or pitting the metal beneath. Soda blasting leaves a fairly smooth, even surface. It is also good for other types of materials that are too delicate for more destructive abrasives.
Sandblasting grit, which is also called blast media, comes in many other forms, including glass beads, aluminum oxide grit, ground glass, steel shot, bits of cut wire, copper and coal slag, silicon carbide grit and ground industrial gems. All of these types of blasting media are available in several sizes.