I didn't use anything special in the sand. Just bought it from the local parts house. It was only about $8 a bag from them. I use glass bead in my cabinet for cleaning parts for powder coat.
If you watch the video shots of soda blasting online you may notice they really tape and cover up everything not being blasted. The soda is very fine and will get into everything not covered. They even completely tape off the interior in many of the pics. Takes time but not real expensive and the results look to be worth it.
Check Eastwoods catalog or website for some ideas on which media to use they break it down pretty well. By the way I'm a satisfied user of Eastwood products, not a schill for the company! 
Chuck in NH
Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.


MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire