In Reply to: Or plastic beads, the aviation industry uses posted by Rainman on August 07, 2001 at 16:31:51:
plastic beads on repaints because it won't distort the thin aluminum panels or remove any of the base metal, only the paint.
Bead blasting engine parts such as the valve cover is a highly risky undertaking. Glass beads somehow find a way to stay in nooks and crannies no matter how well you clean the parts.
Naturally, as soon as you run the engine and oil hits the parts, the same beads happily flow out and go hunting for bearings.
If you absolutely must blast, use walnut shells.