In compliance with the California Air Resource Board, certain sand grades that GSCo produces undergo standard test. Passing the tests mean that the sand if "certified for permissible dry outdoor blasting".  Painting contractors, in particular, use the sand for surface preparation.
The MATERIAL SAFETY DATA SHEET contains technical information about the sand, and serves as a reference on how to handle the material.
This diagram shows the "Wet Sand Production" and "Dry Sand Production" at the Gordon Sand Co. plant in Guadalupe, CA.