dave, i believe i got hold of some #10 aluminm once. i blasted a frame with it and it threw sparks and raised cane. damn near ruint a frame. they used it to blast the inside of tanker trailers so it was probly the coarse stuff. so far so good with my setup. i'm using really low preasure and seems to be working fine. glad your around to put some real knowlege of the products in here. helps a lot. thanks