I have a student in my darkroom class who will be bringing in to develop a roll of Plenachrome 120 film that was in an old box camera he just purchased. Since this film is 50 years old or more, I expect it is fogged. Would it help to add some Benzotriazole solution? I have some on hand and the container says that it is used for paper, but could it help the film? We have no idea how long to develop the film in Xtol, but I expect we can't overdevelop it. We don't expect this film will yield much, but what the heck, we have to try. Janet Ness