we no longer sandblast signage after our outsourced sandblaster destroyed a HUGE project of ours and tried blaming us for it.
(i was never a fan of relying on sandblasting mask to stay stuck to the board during blasting anyways, there were always little errors we had to fix due to blowing under... but on the big project referenced, they did 10-4x8 panels for us and ruined them ALL... claiming our mask came off during blasting. But who the hell does ALL 10 panels if you notice mask coming undone?!? It was as if they blasted at a 15degree angle, just completely ignoring the need/use of sandblasting mask. They even took us to claims for their labor we refused to pay... and we couldn't claim our boards against them, since its the nature of their work to "destroy" the boards)
We route everything out of HDU foam boards and hand-carve any details our smallest bits cannot. For glass etching we just use frosted vinyl... much cheaper than the labor required and/or replacing glass when clients want to change logos or add content.