Bead blasting is glass media blasting with very fine clean glass beads. It leaves a "dust" finish. The beads I use are smaller than granular sugar.
It takes a very light dusting... too much pressure or if nozzle too close, the part will turn out blotchy.
When anodizing a part that is going to be left clear, the part must be absolutly perfect before going in the tank.
Also, I usually ano to only .5mil so that the ano doesn't turn yellow, then seal normally.
Here is a dust clear compared to white powder coating:
