I guess I'll add my opinion. I work part-time for monument company (granite). I have them blast my panels and frame of my pump. The medium they use is silica. They reduce their pressure so they won't warp the panels. If you stay in one place to long it creates a lot of heat. Therefore you must constantly move your nozzle and not concentrate on one spot to long. Their was disagreement among two of my co-workers, one said it would warp the other said no. I agreed with the no answer and the panels came out great. It all depends who is doing the work.
