What do I need to consider when sandcarving stone?

Sandcarving stone pieces presents several unique issues that must be considered. First, the surface of the stone that is to be blasted must be as smooth as possible. This allows for complete adhesion of the mask. Generally, this can be accomplished by sanding or light grinding, depending on the type of stone. Second, the stone must be of solid consistency and not prone to flaking or cracking. Granite, marble, and limestone seem to be the best choice for this; however, there are other varieties of natural stone worth considering. Finally, applying color (paint) to the finished blast may be the best approach. This, of course, depends on the stone used.

-Dara Burge, The Chizel