In my everlasting quest to find a universal b&w reversal recipe, I'm just beginning to dig into the use of sodium sulfate in the first developer.
As far as I know sodium sulfate is used as an anti-swelling agent. Now the rationale for this is: if I use it in the first developer then my emulsion can't swell much and so it receives the least mechanical insult in the following permanganate bleach.
Now a couple of questions:
1) what's the amount
2) how, on a molecular level, sodium sulfate acts as an anti-swelling agent
3) how does it interfere with the development process (I use Kodak d-19)
Thanks in advance, I can't wait to know...