Recurrent black smearing / streaking on last frames of Kodak 35 mm films (since ~2020)

It would seem that no-one here can be of any help in this matter as we have not experienced it but as you work for a lab and handle many films you might want to consider contacting Kodak

Good luck and if you do contact Kodak let us know what it says in its reply

Thanks

pentaxuser

It would be interesting to sacrifice a couple of rolls of film straight out of an unopened box of Tri-X carefully open the film cassette in the light and inspect the entire film for gouging of the emulsion, especially at the end of the film. I have not seen this, but I don't print every frame. IIRC Ilford does not use tape, but a mechanical lock.

While the opening post makes it clear that the issue is observed with different Kodak films, and different methods of developing the film, it not clear if the problem is commonly observed in different labs.

@Joerg Bergs, how does your lab get the film out of the cassettes, and how is the film removed from the takeup spool? Is this done by human hands, or by some kind of machine?

And is there anything different about the cassettes or takeup spools used by Kodak that would affect your process?

I have been out of the business for a long time but in the 70s as I recall stripping the tape I would see a faint glow from the adhesive could it be the edge of the tape laying on the emulsion?

If it can be confirmed that Kodak uses tape to attach the end of the film to the spool, but Ilford does not, then that could be a significant clue.

Linerider said:

as I recall stripping the tape I would see a faint glow from the adhesive could it be the edge of the tape laying on the emulsion?

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Yes, I have seen light when removing the tape from 120 film. When I took a medium format film class at a local university, the professor advised us to never peel off the tape because static electricity can produce sparks. However, light contamination would cause dark areas on the developed film, right?

But I can imagine the tape might pull off bits of emulsion if the sticky part accidentally contacts the emulsion during the removal process.

Linerider said:

I have been out of the business for a long time but in the 70s as I recall stripping the tape I would see a faint glow from the adhesive could it be the edge of the tape laying on the emulsion?

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I would breathe on the green tape to increase the humidity when I would tear the tape. This seemed to help. Never fogged film as I recall.

Linerider said:

could it be the edge of the tape laying on the emulsion?

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(Welcome to Photrio!) I'd be surprised if that extended all the way into frame 36; the tape is a little further towards the end of the film. IME the tape on Kodak film doesn't extend very far onto the film strip; an inch or so.

koraks said:

(Welcome to Photrio!) I'd be surprised if that extended all the way into frame 36; the tape is a little further towards the end of the film. IME the tape on Kodak film doesn't extend very far onto the film strip; an inch or so.

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I was thinking that if the tape was to allow some of the adhesive to sort of leak out of the end then the first wrap around the spool could get some on it, obviously only on the very last frame 36+.

Steve906 said:

I was thinking that if the tape was to allow some of the adhesive to sort of leak out of the end then the first wrap around the spool could get some on it, obviously only on the very last frame 36+.

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You might just be on to something with that theory. That's the best explanation I've heard so far.