Fogged Paper

From Silvergrain Research

What can one do with an old stock of enlarging paper is a common topic, for which various recommendations are passed around.

Frankly, you can give it away to someone who practices an alt-process that uses paper base and not the emulsion. The way fog centers are created on modern emulsions during long storage is different from how other kinds of fog occur, and there is really nothing you can do to make it work like a new stock.

Many darkroom books say you can salvage the fogged stock with addition of KBr and benzotriazole (BTA). In my experience, that never works unless the fog is very slight. I have many kinds of organic antifoggants besides BTA, most of which are much more potent than BTA, but none of them could selectively suppress fog while keeping the image unaffected. Those additions will slow down the development and may also require greater exposure, but when the image comes to the right density, fog will appear and you'll also see reduced highlight contrast.

Whether the old books provided erroneous information or the information got stale with the modern paper, I do not know. However, if you look around online discussion, many people seem to pass this suggestion without testing for themselves.