Fogging and Black and White Films

[JPSuisse]

Hello all

I'm going through a batch of Tri-X right now that expired in 2011. (I thought I would use some of it to test Tri-X with ACUROL-N. See the other thread about that...) The first 2 rolls look totally normal when looking at the base...

With all the talk about fogging, I have to admit that I have never had film with fogging on it. One color film, an AGFA roll, I even let be developed 8 years after I shot it and it completely looked normal when scanned! I do have some slighty expired Neopan 1600 and suspect this might be fogged...

When does this effect really start for say a fast speed film like ISO 400? I store all my film (not particularly carefully) in the fridge (not freezer) but live around the same latitude as Toronto. Does film fog less quickly up here?

Cheers, John

 

[waileong]

X-ray fogging can occur if the machine is not film safe or the film is high ISO like 1600.

Cosmic radiation can happen to 20-year old film. See http://www.rangefinderforum.com/forums/showthread.php?t=119713&highlight=cosmic

 

[Fotohuis]

Fogging of =>iso 400 film will start around 5 years past expiration date. It depends how the film was stored.
So I should not be worried about your 2011 Tri-X (400) films in the fridge.

In case of heavily expired films you can use HC-110 which is containing Benzotriazole to suppress the fog.
Or add 0,1% Benzotriazole to the developer or use Potassiumbromide (KBr) 0,5%-1% instead.
A stable 1% Benzotriazole solution you can make by dissolving 1g Benzotriazole /100ml IPA (Iso Propyl Alcohol).

Slow speed films are fogging very slowly. In case of APX-25, Efke 25 and freezing them you can use them at least 20 years over expiration date. Slow speed films are also picking up cosmic radiation on a minimum level were ultra high speed films (=>iso 1600) you can throw away 5 years over expiration date.

 

[Steve M.]

It really isn't possible to pin down how long it will take, as it depends on how it's stored. If it's stored in the freezer, it will be good for quite some time. If it's kept in a home in Florida w/o A/C in the summer, it won't last long.