Archived negatives have excessive shift. Ideas? Help?

[koraks]

What year did C41 film manufacturing change to formalin-free stabilizer? Was that date uniform across all manufacturers?

Likely not. The changeover revolved around improved dye couplers. Since this is typically highly protected intellectual property of the various manufacturers, they will have had different moments of introduction between brands but also between individual product lines. I couldn't put a date on it but I suspect it's likely to be in the 1995-2000 time slot. I have no evidence for this though; it might as well have been earlier.

 

[GBS]

Likely not. The changeover revolved around improved dye couplers. Since this is typically highly protected intellectual property of the various manufacturers, they will have had different moments of introduction between brands but also between individual product lines. I couldn't put a date on it but I suspect it's likely to be in the 1995-2000 time slot. I have no evidence for this though; it might as well have been earlier.

@koraks Thanks. that makes sense why it's hard to find. Seems like lab employees would've been aware. Still, I wonder if my yellowing negs were simply intended for formalin but got the formalin-free stabilizer. Seems like that would've happened more often to others, though. Anyway, thanks. As a precaution, I'll use formalin on the damaged ones as I come across them.