Soda media really requires a proper cabinet to use. Even too high of humidity will fuck up your gun and cause it to not feed. Our soda blasting machine is a finiky bitch and we spend more time making it work right than actually blasting parts. It’s a big machine though, can fit a Triton V10 block on the turbtable easy, so it’s got alot of volume to absorb moisture.
Stick with an 800-1K grit oxide media. Walnut works good too, just set your blaster up for it as it jams easy. You can prework the paint by slathering paint stripper on it and just letting them sit to dry completely. buy a few cans of aerosol paint stripper to make it even easier. It breaks the adhesion and makes the blasting process go 1000x quicker. Piant blasts right off in sheets.