Still, there is a case for using old paper. Of course, old paper runs the gamut from light to heavy and dense fog but, more ominously, from inconsistencies like spots or uneven fog, mottle, etc.
But...if you have a packet that is consistent, up to medium fog, you can make prints that are virtually the same as from fresh paper. It will take more work, however.
First, you develop with either potassium bromide or benzotriazole. Use a 10% solution of the PB or a 1% solution of the BZ. Initially, add about 50ml per liter of working solution of developer. I know that that is a lot but you need a lot. For tests, make certain that you leave a portion of the paper completely unexposed by either placing a coin (hold it down during exposure) or other heavy, flat, opaque material. This is done to be able to judge whiteness in the unexposed part.
After fixation, look carefully at that unexposed part. Chances are that there STILL will be grey fog, albeit less so than if restrainer was not used. Now, the final stage: you need weak Farmers Reducer (single solution) in order to make that fog completely retreat back to whiteness. The benefit of Farmers is that it attacks the lighter parts a lot quicker than the darker parts, so your dense blacks will usually stay delightfully dense.
Much experimention and testing is needed here. You learn quickly that you have to have a denser print when you do this, so that after the reduction with Farmers you are back to normal with that slight addition to contrast that the reduction emphasis on the lighter densities achieves. - David Lyga
