Sand Blasting Techniques

Almost all hard materials may undergo the sandblasting process except for the hardest one, the diamond. Stone, especially stone used to make gravestones, is generally sandblasted. Metal may be sandblasted as well, although this form of sandblasting is used more as a cleaning technique to eliminate rust and to smooth out rough edges to prime the metal for adhesive coatings. Brick and wood are also commonly sandblasted in order to take off old paint, oil stains and hard-to-remove dirt. Brick and wood may also be sandblasted in order to prime the material(s) for painting or staining. Even some forms of plastics are good candidates for sandblasting, usually done for decorative purposes. Since plastic is a little bit more malleable, sandblasting must be done with a little bit more care. Glass is another very popular material for sandblasting, but the purpose of sandblasting glass is often more decorative. Sandblasting can etch images and patterns on glass to decorate vases, bowls and sculptures. The frosted effect on some glass is also done through sandblasting.

The primary task in sandblasting is creating a two-dimensional design or pattern such as stars, hearts or name initials. A piece of vinyl sheet or rubber is placed on the material to be sandblasted. The vinyl sheet, also referred to as the "sandblast resist," is put on the other item to "resist" the effects of the procedure's abrasive technique. This method transfers the pattern to the resist medium with either the use of carbon paper, pencil, or ink, through a pouncing method. Some portions of the pattern are cut and removed so that the uncovered areas will be subject to the abrasive steaming of the sandblaster. This method, wherein only partial areas of the pattern's image are etched, is called positive etch. On the other hand, an alternate etch or negative etch is done by keeping the resist on the design pattern and disregarding its background portion.

Other techniques involve the use of a technology that employs a UV-sensitive film for glass carving. Resists can be made by using its photographic techniques. The procedure involves creating line art, producing a film image of the pattern or art, exposing resist material to UV light, washing the material to make openings where the abrasives will pass, placing the resist on glass and finally, blasting it.

The actual blasting process involves pressurizing the sandblaster's pressure pot to blast the material (with 2 to 6 inches distance away from the material). A painting or brushing motion is used to create an etch on a glass.

After the blasting, etching and carving are done, the material is carefully washed with water. It must be handled with care to avoid scratches.

Abrasive media or material must be used to sandblast. The most common pieces of equipment used include sand, walnut shells, aluminum oxide or plastic pellets. The actual sandblaster will most likely have a compressor, media screen, pressure pot, a nozzle and a dust collector.