Ok, another thread like the one on Stop Bath use I guess.
Any wash aid is better with FB papers than it is with RC papers. That said, it does help with the emulsion itself to a tiny amount.
Emulsions are like ion exchange resins. In fact, they resemble a mixed bed resin, having both positive and negative charges. Gelatin, or rather the amino acids it is made of, likes to hold on to both positive and negative ions. It also likes to surround them with its coils and "embrace" them. Thiosulfate is a big negative ion, having both Sulfur and Oxygen bound together with a double negative charge. It is held on tightly. Complexed with Silver it is bigger and more tightly bound. In fact there are at least 5 different complexes of Silver with Thiosulfate and some of these are very huge.
What you need to do is remove them by water, and lots of it, or with a big dose of an ion, or to destroy the hypo itself. Paper holds onto this as well. The sizing agents that make paper work, are also liable to hold on to Hypo. HCA is a big dose of ions. It is like washing out an ion exchange resin with an inert salt. Thus, any inert salt will work. HCA uses Sulfite. Seawater would work, but I am not aware of any Sulfite present, just the usual mix of Halides. That is why regular salt will work.
Thus you have the sale of a rather inert chemical to remove Hypo when water would do the trick. You have more chemistry to dispose of, one way or another, and you still have to wash the film or paper to get rid of the HCA. Now, there is a test for residual Silver and residual Hypo, but none for residual HCA!
There is a simplified explanation of HCA. As to using it? I never have. I have had no problems in all of my years except for pictures made when I was about 8 years old. I did not wash enough. Of course back then, I had to be reminded to wash behind my ears.
And thank you John.
PE