Grain increase in outdated film

[Oldtimer Jay]

Hi All,

In a post over on Photo Net Scott Pickering and I both commented that when comparing prints from frozen, outdated Panatomic X, to prints shot with fresh film in the 70s, grain is much more noticable. Fog, ISO and tonality are not at all issues but grain is. Another poster in that forum commented that he noted a substantial increase in grain in FP4 as it got further and further past its eexpiry date.

Perhaps PE or other highly knowledgable folks could comment on this phenomon and what causes it. Obviously I would be delighted if there was some way to correct for it but I have tried numerous developers and feel that even though there is probably no way to fix it I would at least like to understand it.

Thanks in Advance,

Jay L.

 

[George Papantoniou]

This is a typical effect of film being frozen for a long time. In the freezer, the silver halide gets too cold and tends to gather in groups in order to keep warm (think about penguins in the antarctica). So, the grains get bigger...

A practical solution to this problem would be to pull the film from its cassette before exposure and warm it up with a hair dryer. This will make the silver halides get warm and happy and have them run around (they will actually think that spring has come) so when they're exposed and developed they will not be found gathered in large groups. Another solution is to have a polar bear released on the surface of the film, that will scare the halides and make them run around, in order to produce the same effect.

You see what happens when no serious person responds to a difficult question ? I happen to notice it and start saying stupid things.

 

[Ryuji]

There are a lot of studies on emulsion, but researches on granularity and researches on aging are both less common than researches on sensitometry. So I don't have a very good answer to that.

However, if you put a gun on my head and ask for my best guess, I'll tell you the following.

One possibility is the difference in development. In the old days of Panatomic-X, most skilled darkroom workers made rather thin negatives and printed them very carefully. With old emulsions, thinner negatives gave better granularity and also better resolution. This is also true of modern negatives but not as pronouncedly so. So many young darkroom workers prefer to see dark, robust negatives. Sort of like the difference between the old world wine and the new world wine.

Another possibility is due to subthreshold fogging. Due to slow chemical changes and also radiation, emulsions can build up fogging, but slow emulsions, especially if frozen, have a long period of time before the fog becomes visible after development. The subthreshold fogging creates a very tiny silver speck in the emulsion that can change the way latent image center is created on the grain. And the size and the location (within a single grain) of the latent image can have a large influence over the rate of development and the size of the developed grain. The best way to test this factor would be to test for high intensity reciprocity failure. You would've had to test it before and after aging and compare if there's any changes with sensitivity when the film is exposed with very narrow (1, 10 or 100 microseconds) pulse of light.