One of the first steps to a commercial painting project is the removal of the old paint from the surface. Blasting is a removal method that shoots abrasive particles at the painted surface. The particles impact the finish and scour or chip away the paint. Depending on the abrasive material used, the substrate, or surface underneath the paint may be affected by the blasting procedure.

Compressed air is one of the most common propellants used for a blasting system. An air compressor blasts air into a mixing chamber, which also receives the abrasive medium from a storage chamber. The compressed air is mixed with the abrasive medium and shot through a low diameter aperture.

The resulting forceful blast of air enhances the abrasive characteristics of the shot material and weakens the adhesive bond between the paint and the treated surface. As more and more of the paint is stripped from the surface, the abrasive materials act directly on the surface.

Some of the abrasive materials used by commercial painting contractors include sand, steel shot or grit and water. Advances in blasting technology have led to the use of plastic and dry ice as abrasive materials. Also, the pressures used for delivery have decreased as abrasive technology has advanced.

Each type of material affects the substrate differently, so some types of blasting are more suitable for certain materials and applications.

Coming Up: Shot Blasting in Detail