JPD, thank you, but my question is very specifically about the formulation in the new edition of The Darkroom Cookbook - the high proportion of 28% Acetic acid caught my eye and I'm curious. I use 15 g/l Citric acid stop for printing and half-strength SB-1 Acetic acid stop for film, both one-shot, and have no plans to change that practice.
Pentaxuser, the Cookbook's stop bath, which I believe is a Bill Troop formulation, claims a capacity of 40 8x10 per liter, which is a lot more than a non-buffered stop could do. There's no mention of dilution for use so the implication is to use as-formulated. It's pH is stated to be higher than a simple acetic acid stop (though still low enough to be effective), and because of the buffering it holds pretty close to that pH until nearly exhausted. He also claims it's very quick-acting, as little as 3 seconds, which he says is faster than something like the standard indicator stop (the SB-1 formula with indicator). The same amount of 28% Acetic acid will make 2.5 liters of SB-1 and give approximately the same capacity, so I also wonder what the real benefits of the buffering would be. If my film spends 10-15 minutes being developed, what does it matter if it stops in 3 seconds versus 10?
I'm hoping one of the chemists on Photrio can enlighten me.