crushed glass most everything but aluminum 45-60psi
walnuts for aluminum 50-60psi
black slag for the really grungy stuff like frames and suspension stuff. 60-80psi
I use crushed glass also to clean up mildly dirty parts BUT I only use 45-60 psi since it turns pretty much to dust at 100psi. I have a harbor freight cabinet (had to reseal EVERYTHING) and put in a good light. then got a TP tools gun and it made a world of difference. Now I can go down as low a 50psi for walnuts, that would never happen with the HF gun(it stayed at 90psi or better just to pick up the stuff.
