Well - it finally happened to me! After 45 years, I managed to damage a negative during processing – I think. While processing a 4x5 sheet of Ilford FP4, some very strange dark “lines” were produced. I used the description “lines” because that best describes the striations observed. These faults appear as broad, sweeping, dark brush marks running from one 5” side to the other at a slight angle of about 3 degrees. Some “lines” begin at the edge and run three quarter way across then stop with a very angular blocked appearance, as if there might have been a light shadow. Most of the effects were minimized by re-fixing a very long time (a couple of hours) followed by an additional thorough washing. I wish I could scan the darn thing, or make a macro and post it. Even then it would probably not be representative. The “line” can best be seen by looking at the emulsion side at a narrow angle to a bright light. It certainly seems like a deposit of some sort. I wish I had looked more carefully at the negative from the fixer. How can it be a deposit when I am so careful in the darkroom? Actually I have had several accidents but in this case I can think of nothing I have done to produce the observed effects. I processed this negative separately in a 5x7 tray of D76 (off the shelf but filtered and unused). Indicator stop bath and Kodak Fixer full strength, also fresh from the storage bottle. Washing was done in one of those little Kmart “organizer” metal baskets I described recently in another APUG thread. Final rinse was in distilled water with a very small amount Triton-X100 wetting agent (active ingredient in Kodak Photo-Flow. The “repaired” negative was washed in a fresh batch of the same concoction mixed in about half 97% isopropyl alcohol. While the lines can still be seen at the proper angle, they seem to be greatly reduced. Do you think something could have leached out (off) the baskets and onto the film, or what?