Sand is the worst thing to use in a sand blaster. I got my abrasives from Harbor Freight, but pick it up, don't have it shipped. I didn't want a barrel full, just 5 - 50 lbs. at a time. I read one needs 7 cu. ft. per minute of air at 90 psi to blast well. Check your compressor output, and adjust output to get adequate pressure at the end of the hose. I had a gauge with fitting to plug in the end of the hose before plugging in blaster. Blasting sheet metal hardens the surface (shot-peening), but steel frames are ideal candidates. Glass bead is wonderful, but expensive & needs to be recovered. ALWAYS wear a respirator, not a dust mask. When a surface is properly blasted it is mechanically & chemically clean, but rust begins as soon as you stop blasting. Prime it right away. Take off heavy dirt & grease before blasting. Most common abrasives will eat metal, so keep moving & don't overdo it. The surface will be etched, not smooth. Primer levels it out. Most blasting media eventually wear out (breaks down). Don't expect 20 lbs. to be a "lifetime" supply. On a brazed frame the bronze is softer. Don't blast joint areas as much as all steel areas. On alloy frames I'd use chemical stripper instead.
That's what i know about blasting, in a nut shell. (You can buy ground walnut shells to blast with.) I saw plastic media results. One could blast the paint off an aluminum soda can without distortion, but it's expensive. The net is a great place to research industrial topics like blasting.
I hope this has will be helpful to someone.
There are lots of shade tree types who will argue with several points here. At work we always followed these rules to get consistent results with minimal hassle. And keep your powder dry!
