It is worth noting that the other formulas that arrive at p-aminophenolate via one of the 4-aminophenol derivatives (paracetamol, metol etc) all produce different salts, Na or K acetate in the case of paracetamol, for instance. I think while there may be very slight differences caused by these different salts, it is of rather academic interest at the dilutions the developer is used at. Put differently, I do not see much of an influence that isn't offset by a gain in affordability or ease of preparation. They all behave essentially like Rodinal. It is however important to get the final hydroxide balance correct. Some formulas have way too much hydroxide in them, and this causes severe fogging. It is also necessary to use potassium based chemicals for at least the sulphite or hydroxide (preferably both), otherwise the solubility of the aminophenolate is insufficient. There are many instances of only sodium being prescribed. These formulas are 20% deficient in active developer, and die quickly (+- 3 months). I am not sure why their longevity is not the same, but I can definitively say that my method produces long-lived parodinal. Any questions, PM me. I'd be happy to help.
Originally Posted by Ian Grant
As for adding table salt to Rodinal: I wouldn't do that. The iodide content is far too high (and possibly varies wildly from product to product), and iodide is a stronger restrainer than bromide. So one can expect unpredictable results. If one must, then start by using AR grade NaCl, so at least you can benchmark with that first.