I'm about to get started experimenting with VDB prints and just received the kit from Bostick & Sullivan which includes a 250g bottle of sodium thiosulfate crystals. I've read plenty about the actual process but nobody seems to say much on how many times the fixer solution can be reused (if at all). Our lab uses only rapid fixer so I'd like to keep reusing/rationing this stuff until I can get some more. Lastly, would using hypo check in the fix contaminate anything for the print? If anyone can help, thanks!