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

[pentaxuser]

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

 

[mshchem]

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.

 

[runswithsizzers]

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?

 

[Linerider]

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?

 

[runswithsizzers]

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.

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?

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.

 

[mshchem]

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?

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.

 

[koraks]

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

(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.

 

[Steve906]

(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.

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+.

 

[John Wiegerink]

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+.

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

 

[brbo]

Checked closer and found a number of Kodak negatives with this problem!

All on BW Kodak films, not a single on Kodak C-41. My C-41 to BW ratio is probably 10:1, so it was easy to miss at first as OP said that all Kodak films are affected equally. In my case I'd expect at least some of C-41 to have this problem. Hmm...

I can't think of a thing that I do differently when handling BW film vs. C-41 that would cause this.

 

[calebarchie]

Checked closer and found a number of Kodak negatives with this problem!

All on BW Kodak films, not a single on Kodak C-41. My C-41 to BW ratio is probably 10:1, so it was easy to miss at first as OP said that all Kodak films are affected equally. In my case I'd expect at least some of C-41 to have this problem. Hmm...

I can't think of a thing that I do differently when handling BW film vs. C-41 that would cause this.

When was your C41 film manufactured? It certainly affects C41 as well and what is even more concerning is I may be starting to see the same issue on 120 too.

 

[Lachlan Young]

It's possibly a form of stretch marking from the film being pulled too tight, but not quite tearing.

35 exposures on a roll is considerably more sane and convenient.

 

[koraks]

35 exposures on a roll is considerably more sane and convenient.

I don't follow to be honest. It's officially a 36 exp. film. Many cameras like most of the EOS series will expose exactly 36 frames on a nominal 36 exp roll. Most film over the past decades has performed fine that way from the first frame to the last; there's already a safety margin in both the leader and trailer ends of the film. I don't see how it's reasonable to accommodate for what now starts to look like a manufacturing defect by rewinding early.

Let's call a spade a spade - it's a defect and it's not supposed to be there, regardless if it's frame 36, 1 or 18.

 

[Lachlan Young]

I don't follow to be honest. It's officially a 36 exp. film. Many cameras like most of the EOS series will expose exactly 36 frames on a nominal 36 exp roll. Most film over the past decades has performed fine that way from the first frame to the last; there's already a safety margin in both the leader and trailer ends of the film. I don't see how it's reasonable to accommodate for what now starts to look like a manufacturing defect by rewinding early.

Let's call a spade a spade - it's a defect and it's not supposed to be there, regardless if it's frame 36, 1 or 18.

7 strips of 5 fit on 8x10 much more comfortably than 36, and you aren't running the risk of ripping the film off the spool. Quite a few people used to aim for 30/ roll as it eliminated their chances of tearing the film off if they exposed a few extra frames in the heat of the moment. A 'defect' out by the tape and beyond the end of frame 36 isn't a defect, it's an artefact of how the film is cut, attached to the core and spooled.

The machine that does the cutting/ taping/ staking of the canisters is on pg.290 of Bob Shanebrook's book. Station 5 is where tape, film and spool are stuck together, and it's pretty obvious from the way it works that it delivers a tight nip on the end of the film. The substrates used will determine how much force needs to be used - and polyester base may need more than CTA, hence marking on CTA bases.

 

[koraks]

7 strips of 5 fit on 8x10 much more comfortably than 36

There's also arguments for 6-image strips such as scanners that accommodate this strip length. YMMV and all that. I don't think it makes much sense to argue that 7x5 is somehow better than 6x6 or any other configuration without taking into account specific user requirements and context.

A 'defect' out by the tape and beyond the end of frame 36 isn't a defect

The defect as shown is firmly WITHIN frame 36 as indicated by the manufacturer's edge imprint and thus within the area of the film officially intended for image-making.

The machine that does the cutting/ taping/ staking of the canisters is on pg.290 of Bob Shanebrook's book.

The book predates the recent expansion of confectioning at Eastman Kodak and thus it's not certain that the presently used equipment works the same as the equipment shown in the book. It's entirely plausible that a new conceptual design will involve new failure modes.

 

[brbo]

When was your C41 film manufactured? It certainly affects C41 as well and what is even more concerning is I may be starting to see the same issue on 120 too.

It's not that hard to understand that OP is looking for input on Kodak film produced at about 2020 and later. And I went and had a look at my films that met that criteria. I couldn't find (yet?) a C-41 roll with the defects I'm seeing on my Kodak BW.

 

[Lachlan Young]

It's entirely plausible that a new conceptual design will involve new failure modes.

I've processed plenty of Kodak 135 film (BW and colour) in the same time period (some even shot to the end of the roll) and not seen the same defects, even on Tmax 3200 which can be pretty sensitive (I've seen others, including canister lip tensioning problems on Kentmere 400). However, I am not using an RT machine and always break open the canister for loading reels, so I am not tensioning the end of the film hard. If the length of the film has been shortened even by just a little, systems that rely on that bit of slack at the end of the roll are going to produce problems.