I'm not sure that sodium benzenesolfonate came from Agfa - the book states it was proposed by one of russian scientists as an agent preventing oxigen diffusion into the stock solution of Rodinal. It was stressed about diffusion, but not oxidation. And for me this makes the point - if there is no diffusion, there is no oxidation. But from practice it is also an anti-oxidant.
Originally Posted by Ian Grant
I mixed two batches with benzenesolfonate and without and there is huge difference:
1. First batch was without it, and when I got right NaOH content, I've added water to make 1 liter. It was light in color before water, and became much darken when I added. Obviously, water contained a lot of oxigen, which oxidized pAP, and I had color change.
2. Second batch - I added benzensulfonate, and after adding the water to make 1 liter, there is no color change.
One of my friends told me that he noted shelf life difference for rodinal made with benzenesolfonate and without from his previuos experience.