Gotta give credit - long ago I learned this from Bob Gorsuch at Excello Plating -
Glass beading tears up the surface. It leaves a surface that harbors, almost sucks up, oil and dirt. You can follow it with a rattle can clear coat and that's an OK result.
Better still is if you follow glass beading with shot peening. The shot will close the metal torn up by the grit/glass blasting; the peening closes the pores. As a side benefit, shot peening, generally speaking, improves the strength/durability of most parts it is used on.
A basic detergent or solvent cleaning followed by a "one - two" of glass beading followed by peening, particularly with cast aluminum, makes for a beautiful finish. Peening however, because of the greater weight of the media, takes a high powered system . . . . lots of psi and cfm . . . and unless you like changing media, you really need two blasters, you want to keep the grit out of and away from the shot. Different nozzles . . .
Avoid using sand, unless it is pure white. It contains iron which gets embedded into aluminum and then rusts. It also explodes on impact, turns to dust, has a short life. Penny wise pound foolish.
Lastly, hook up a shop vac to your media blaster system, it helps the Bernoulli effect of the nozzle in picking up the media (less clogs) but more importantly it keeps the cabinet clear of dust and you can SEE what you're doing. It also means that your face mask is more effective and has less work to do.
So, for most folks, it's best to drop your parts at a pro blasting shop that does shot peening . . . .
