In all cases where we are using film past its expiration date, the only safe approach is to try a roll OF EACH
PRODUCT and evaluate it before shooting the rest of that product. The stability of film products is different for different
products.
Having said that, here are some general guidelines. The expiration date for many products is about 2 years after
manufacture. Refrigeration will preserve the the chemical properties of film for 2 to 4 times longer than at room
temperature. If you bought fresh film and refrigerated it, the chemical properties should last 4 to 8 years
instead of 2.
Freezing will preserve the chemical properties for something like 8 to 16 times longer than at room temperature.
Frozen film can be expected to maintain chemical properties for 16 to 32 years.
Unless you have access to a salt mine, background radiation cannot be stopped by any process that any of us can
afford. Background radiation causes fog and grain increases in the shadow areas. All films are sensitive to
background radiation ROUGHLY in proportion to film speed. That is, an 800 speed film would be roughly 32 times as
sensitive as a 25 speed film. This is very rough since the current Kodak 800 speed film is about 1/4 as sensitive as
the generation from 8 years ago. All these discussions of keeping film in a refrigerator or freezer should only apply to
low speed films (200 or slower). With high speed films, the background radiation will degrade the film regardless of
the storage temperature.
FWIW, I've shot K-64 that had been in my freezer for 20 years with good results. I don't shoot 800 speed film that has
only 6 months until expiration.
