I have been going through my considerable stockpile of 35mm film to test various acquisitions, and I recently tested some expired Kodak Vision 320T film. It is an ECN-2 negative film and was allegedly cold stored before (and during) my acquisition. It's probably about ten years old or maybe more.
Per the attached thumbnails, you can see that the top edge of the film seems more exposed than than the rest of the film. It also seems to have a somewhat different color balance. I am trying to figure what would cause this.
One thought is that perhaps the top edge has lost less speed than the rest of the film. Another thought is that perhaps one of the layers may have lost sensitivity along the top edge (eg yellow). It could be a processing error, but the same problem showed up on separate films developed with separate, freshly mixed batches of developer (although the other chemistry including the ferricyanide bleach was shared).
It does seem that the film has lost speed - it was exposed at its rated speed (effective speed 125ASA using an 85B filter).
I wonder if the phenomenon shown would be mitigated if I reduced the EI of the film to say 64ASA with the filter or even 32 ASA. I guess the only way to find out is to run the test.
Meanwhile any thoughts would be greatly appreciated.