Hi all, I'm reviving this thread because it discusses vinegar syndrome, the subject of my post. The admins can move it if necessary to the appropriate place.
I'm currently scanning some colour negatives that my father exposed in the 1960s and 1970s for retouching and archiving. Some of these (too many!) are cut into individual negatives - as seemed to be the norm back then. On these individual negs, there's a distinct line of tobacco-brown 'stain' (in positive) along the edges of the image area adjacent to the cut edges. The film is 120 format, Kodacolor X and Kodacolor II, and the former appear more affected by this (because they're older, or different process?). These have been stored in mostly glassine neg bags inside paper envelopes in UK domestic conditions, not particularly humid.
I wonder whether this could be the starting point of vinegar syndrome deterioration, or is it something else - environmental contamination perhaps?
Here's an example; note the discolouration along the top edge: http://s20.postimage.org/4okhy9afh/abington4.jpg