Soda blasting is pretty gentle to aluminum compared to the more typical glass beads, crushed glass, steel grit, but can still be overdone with high pressures. One other advantage is easier cleanup and lesser chance of abrasive residue being embedded in the surfaces of treated parts.
Walnut shells and plastic media do a nice job on aluminum, but if the desire is to leave a rough, pearl or satin finish, glass beads work well. Coarse glass beads leave a pearl silver color to aluminum, where fine leaves a primer gray color. Parts blasted with coarse look best with no further treatment or clear coating, the fine is great for painting.
Structural parts like aluminum connecting rods and the like benefit from bead blasting. It has a shotpeening effect, stabilizing the surface and making cracking less likely.
Aluminum oxide, steel grit, Black Magic and other high cutting abrasives are a last resort on aluminum, these can grind away the profiles of pieces with close tolerances.
