Curious - how long can exposed film be left undeveloped?

No bad press: only same recommendation made by Ilford.
If we've recommended prompt development, it's because we appreciate PanF50+.
Ilford times are OK for common overcast.
10-15% less development times / less agitation for condenser enlarger testing.
Sun scenes are a different story, and not common with PanF.

Just to add some personal experiences,

I shot a roll of the old Tri-X in a Fujica Drive half frame camera, and then lost it for over a decade until we replaced our couch. Developed it and to the eye the negs were perfect. I've had similar with Ilford FP4 and HP5 films that I've found in old cameras. Kodak verichrome Pan seems to lack any kind of awareness of the passage of time. It always seems to work even 60+ years old. A few yeas ago I was given a camera with a roll of Verichrome Pan shot in the early 60s and got perfect negatives out of it. My "go to" regimen is Ilford ID-11 stock for 7 minutes with inversions every minute....on the grounds that if you cannot get an image of some sorts with that, then there was no latent image to be obtained in the first place.

As people say, Pan F is well known for not liking being stored between exposure and development. Colour films also fare worse than B&W but I *have* had a lab get some colour images from C41 film exposed some 42 years before processing.

At the very end of 1993 I inherited a bunch of cameras from my grandmother, some had film in which I developed in 1994 and 2000. they'd been shot in the 1960s again, some could be dated to 1963 as they contained my uncle and aunt moving into their first house together. Not perfect but usable negatives from all the films except the E4 slide film which came out very dark. No lab could scan it, and I eventually got images from it in 2020 during the pandemic using a very bright and diffuse lamp designed to combat seasonal affective disorder as a backlight.

Agulliver said:

Just to add some personal experiences,

I shot a roll of the old Tri-X in a Fujica Drive half frame camera, and then lost it for over a decade until we replaced our couch. ..

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You found it in the couch? You couldn't feel that when you sat on the couch?

Huss said:

You found it in the couch? You couldn't feel that when you sat on the couch?

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Lucky that the couch wasn't vacuum cleaned during that decade, otherwise that film roll could have been sucked up and clogging the tube...

Huss said:

You found it in the couch? You couldn't feel that when you sat on the couch?

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It somehow fell inside the mechanism of a reclining couch, and only revealed itself when I took it apart for disposal! I was quite surprised as I'd long ago assumed I'd accidentally thrown the film out. And thankfully the recliner mechanism didn't damage the canister.

Agulliver said:

It somehow fell inside the mechanism of a reclining couch, and only revealed itself when I took it apart for disposal! I was quite surprised as I'd long ago assumed I'd accidentally thrown the film out. And thankfully the recliner mechanism didn't damage the canister.

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Good you disposed that couch decently instead of just dumping it in the environment, which proved to be rewarding after all!

These days I am sure the kittens would find any such film cassette anywhere in the house, and play with it. They do like rolling them around the floor.

Another anecdote, I bought a Brownie 620 box camera in 2021 and it had a film in it, probably from the 60s. Again Verichrome Pan. Turned out nicely when I developed it, appeared to be a teenager taking photos of their collections of toy cars and model boats. No luck tracing them however.

koraks said:

Depends...
With PanF+, the notorious film when it comes to latent image (in)stability, the advice is to process ASAP, as in within a few days or so. Don't let it sit for weeks. A film like Kodak TMAX100 I think you can pretty safely store away exposed for a month or two and not notice the difference unless you do critical analysis on it. With color film, there's generally slightly less slack, but even that is mostly designed to work well if you take it on a really long holiday and only develop it after weeks. I never really encountered problems even with the occasional roll that was stuck in a camera somewhere for a couple of months.



The image just fades; overall loss of density, the shadows going first. Color film will shift.

I guess we all know those examples of the roll of film forgotten inside a camera and developed after 10/20/30 years exhibiting serious problems. But apart from this, I never experienced latent image stability as a problem.

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I unintentionally left a colour negative film undeveloped for several weeks (I had forgotten about it) and when it was processed the actual colours had shifted, especially where the image should have been green/yellow actually printed grey just like a mono film, changing the filtration made no difference. The other colours, reds and blues had also shifted but could be corrected with filtration but not both at the same time!

It is a number of years since I have used Pan F, possibly even before it was renamed Pan F+ and I was not aware that there could be a problem, perhaps this changed when the emulsion was changed to the + version. I recently saw a note from Ilford in a newsletter I subscribe to and it stated Pan F should be developed within 4 weeks from exposure.
What conditions would make a greater difference was not mentioned, but excess heat has to be a prime contender.