Thanks for your input. Ductility is something new to me, i don't see any tests required under the ams specs for glassbeads, but it seems to be something that affects intensity quite a bit, is there anything in the spec that specifies anything for this? I ve tried using some glassbeads that s very brittle and there seems to be a limit to how high an intensity.(ie even when I increase the air pressure, there doesn't seem to increase the intensity by much). Do you think it s possible there are other factors which could have caused this?