silver gelatin print washing
The Vestal book with the exhaustive (and I do mean exhaustive) info on print washing was "The Art of Black-and-White Enlarging," published 1984. If there's more info about intricacies of washing silver gelatin paper somewhere in this world, I don't want to know about it. In fact it makes me glad to have a nice simple process like gum.
The chapter is some 16 pages long, with diagrams, curves, formulas, and lore of particles of filamentary silver, and black filamentary silver, and particles called colloid silver that wander from their sites -- just to sample one paragraph on page 2.
So I quote another paragraph: "Apparently the thing to do is to wash out all possible hypo, but only in conjunction with selenium toning or gold protective treatment... or sepia toning that converts all the image silver into silver sulfide..." If you want to know the why's & wherefores of that, they are given, but kindly spare me.
Oh, alright, since you insist, here's a snip from the 4th page: "Choosing your method. By 'method' I mean the whole sequence from print fixing through toning, washing-aid treatment and washing to print drying. All the steps are links in a chain... Your choice of fixing method, for instance, may be based on the way you prefer to dry your prints; and the way you fix may tell you what kind of print washer to get. It takes thought and some testing. It's nothing to rush into."
The next 12 pages include "Test Procedures" (with samples from 120 test strips). Also "Archival Print Washers," and "An Experiment with Hypo Elimination." Among others.
However, I did make up the Kodak HT-2 residual hypo test. We used it in class to test our wash of vandyke brown, and it performed just the way it was supposed to. That is, it showed a hefty stain after a short wash, then less and less until almost none after (maybe a 40 minute?) wash... Maybe Ryuji or whoever commented that VDB, et al, may clear differently from gelatin silver paper... and that's not only possible, it's likely -- Still, the VDB wash seemed a simpler, more "logical" or "transparent" progression and, at least as far as I know, lacking the complications of hypo in gelatin, baryta, et al.
Incidentally, Vestal mentions that new clearing, hardening, toning and fixing agents in the pipeline would make archival processing easier and surer... (Tho given his catalog of pitfalls, that's small comfort.) The "enemy " is hidden. In gum, if you get the orange out, you're in the clear... and I'm not sure that even residual orange is a killer (tho I daresay someone else hanging around here will have an answer to that, which may or may not be proven. My own interpretation of "the literature" on the topic is that it's dumb, uncertain and confused. For instance early writers call "clearing" the orange "fixing." And so forth.)
But, meanwhile, wasn't the original print washer question about negatives (????). Negatives are much easier/quicker to wash than paper, so it's quite possible none of this applies.
However, out of the kindness of my kind heart I'll put the formula for the hypo test following.