20 May 2014
DF:
I have been using some very old paper for some time for "work prints" and have noticed fogging. The best way to salvage a fogged paper, as long as it is not to fogged, is to add 15ml/L of 0.2% benzothiazole (BZT). Process a print without any BZT as a reference, then add BZT to the developer and make another print and compare. Repeat this process until you see a change in the degree of fogging. This will not eliminate fogging, but will reduce the amount of fogging. Steve Anchell's book "The Darkroom Cookbook" has a little section on this process.
Hope this helps.
Regards,
Darwin