Ron - the commercial chemistry was sulfuric from the start. The powder sulfamic version was also from the start, but in low-volume retail
do-it-yourself kits. There were minor tweaks and temporary options to both. They offered a higher speed version of pro for certain machines.
I still have quite a bit of the pro chem on hand, more than I need for my remaining stock of frozen paper. Had a friend in here yesterday who
used to run a process line that required a 200 gal tank of the sulfuric bleach on hand. He gave up on Ciba after to had to have a lung removed.
I don't do commercial lab work, so even for big prints used just small volumes one-shot, ran the drums outdoors, etc. It was less noxious in this
mode than RA4 in my opinion. The amateur sulfamic version was slightly less nasty, but icould still mess up someone careless, just like