Each contractor will have to decide for himself where and when they can be economically used. Factors affecting the efficiency of abrasives used for surface preparation for protective coatings include, among other things, abrasive hardness, cutting rate, bulk density, pH, and cost per square foot. Each of these factors is briefly discussed below. Abrasive hardness is measured on the Mohs scale. The hardness of a mineral is its resistance to scratching.
All minerals possess such resistance to a greater or lesser degree.
The Mohs scale of hardness has been universally adopted to test this physical property. The scale rates mineral hardness from one to 10, with talc rating one and diamonds rating 10. This scale is strictly relative and non-linear. The cutting rate can be determined by experimental test blast areas to evaluate the rate of production achieved on any given surface. Bulk density is the weight of the abrasive per unit volume, typically pounds per cubic foot.