Bead Blasting BeCu Heads ??? Help ???

I have got someone to bead blast my Ping BeCu irons - I have told him the dangers, he said he had all the ventilation needed for safety. But he has never done BeCu before only standard golf material.

Has anyone done this before to a set of Ping BeCu irons ??? What beads should we use ??? Glass/Sand ??? How long can you balst for without taking too much material off ??? Is there anything we should know first before doing this ???

Thanks.