Old Kodak Polyfiber Fogging and Treatments?

Forgive my formatting, This is my first post here, I’m hoping some might have some advice. The background: I recently came into possession of an open box containing around 200 sheets of old Kodak polyfiber Double weight F surface paper, my best guess is it’s a mid-90s stock, though I can’t find much info on it. I developed a couple of sheets throughout the box to test it and it’s rather fogged. Some sheets were fogged to about a 30% gray with no exposure, others were fogged less with strips of lighter fogging down the edges. I developed it in Ilford multigrade 1:14 for two minutes, fogging appeared after about 75 seconds, images would begin developing on exposed sheets around a minute, but I could never reach a DMax without base fog. So my question is, should I be using a different developer to reduce fog, or would adding KBr or Kodak Anti-fog #1 (benzotriazol) be helpful in reducing base fog to a manageable level? Thanks!

AFAIK KBr or Benzotriazole are of little use against serious age fog. You can try bleaching it back. Or use it for lith prints if it works for that, fog doesn't matter then. That the fog is uneven is the real issue, if it's just along the borders you can just print with a wide border though. Maybe sheets from further down in the box are better anyway?

That’s good to know, I wasn’t sure to what extent they could restrain fog. The fogging is actually less severe at the edges, which is odd and unfortunately the least convenient. I’ll keep testing the deeper papers to investigate though. If I were to try bleaching out the fog, should I overexpose the paper a bit to compensate? Lith is something I know nothing about atm though given the quantity of paper may be something I’ll be getting into shortly thanks for the help!

Oh man, I’m into fogged papers these days. I have 1000 sheets 5x7 multigrade III, of which I’ve done 500 so far.

What I’ve been doing is this:

a quite concentrated amount of benzorriazole. There is still some annoying fog, but basically muuuuch less than without benzotriazole. But it’s still present.

Once I’m done printing, I quickly bleach the worst ones and refix them. I then I pass them all into a Brown toner (viradon). This gives them a nice brown/oldies touch. In the end, the prints are nowhere perfect but they are all unique and quite easy to admire. The slight fogging gets toned, so it’s not just a gray fogged print that’s easy to hate anymore.
I accept the final prints as Being alternative prints, and in this regard, they become very good. Softish, brownish, easy to the eyes.

Look at it from an alternative printing perspective and you might end up with something very good. In my case, the combination of benzotriazole, bleach, and brown toner, saves the day. But note that this process of saving these papers is at a cost of much harder and longer darkroom work. Basically, the fogged papers are taking double the time to finish.

The goods finally arrived this week and I had a chance to give it a go. I made a 10% solution of KBr and a 2% solution of the benzotriazol (10g BTZ, 500ml water and 1 gram of NaCO3 to balance the pH). In one liter of multigrade, 30 ml of the BTZ solution was enough to significantly curb fog, but not completely (just as you said NB23). I added the KBr by the ml, and at four ml the fog was not noticeable even after five minutes in the developer bath. Upon experimenting with exposure, I’ve found that exposure times lengthened by about 1.5x and that the contrast was rather poor, but IIRC this is common in old paper? The BTZ really took the speed out of the developer though, DMax took nearly four minutes to develop in some of the images. I’m quite glad it’s at least acceptable as I didn’t want to tinker with ferrocyanates and bleaching quite yet
Now, polyfiber is not a paper with developer incorporated emulsion, could that be lending to why the fog is so responsive compared to expired modern paper?