I own a media blasting business and have a bit of experience blasting.
media's use what works for you. you may have some trail and error but you will get the hang of it. when I started my business I bought every single media I could find (in every grit) and figured out what worked best for me.
sand....nope, never. doesn't matter if its free. stay away from silica based medias.
black sand/copperslag /black beauty ect. dirty, has trace amounts of arsenic. hard to clean up.
I use a lot of glass, most glass has basalt added as well. basalt has non active silica. we use it as or go to media I blast 100-200 50-100 30-60 and 20-50 grits. I like the 50-100 the best for its smooth uniform finish. very clean.
walnut. usually 70 grit. works well, doesn't remove rust.
soda, nice smooth finish. no rust removal
aluminum oxide. dusty. smooth finish, hard material so it digs well.
beads. smooth almost polished finish.
I do not use a syphon cabinet, I have a normal cabinet that we have modded to use a pressure pot on and a good dust system. we drain the spend media out of the bottom and either reuse or pitch depending on its condition. if I still owned a syphon I would go on ebay and look up tacomacompany for a hot rodded gun or convert your cabinet over to a real pressure pot if you have the cfm.
with you guys using a shop vac. make sure the cabinet is supplied with fresh air. makes a huge difference. with the vac attached to the cabinet, put some steel wool in the pipe so you can keep out big clunks.
blast pressure. I blast 90-100 on most stuff. really gentle stuff I will go 60psi.
here is my cabinet. LOTS of room
if you guys have any questions on blasting I would be happy to help. I love to debunk sandblasting myth's
