Thanks, Julio. This formula can get you to ISO 40 or so if you're careful (encroaching non-image fog is the risk if you push it too far), which is pretty darn close to what I think is the real ISO of the new Ferrania P30, of which I just shot my first roll.
PF, yes, that's a lot of the fun for me. Plus I simply enjoy being able to do things from scratch, and frequently do whether in photography, woodworking, or cooking. Not an absolute requirement -- I'm not a glutton for extra work. But knowing basic techniques seems to help everything -- what I've learned from these historic practices, whether dry plates, carbon printing, salt printing, or what-not, has helped my photography regardless of technology. Forced me to learn more about light...