BW film lasts the longest, right? My question is how long. Tmax100, Delta100. I hear two years you'll be safe. What helps film stay safe in all its technical terms, what are the temperatures?

-- Albert H. (ai312@freenet.hamilton.on.ca), November 02, 1997

Answers

Freezing is best, otherwise just keep it cold (ie fridge).

If it's kept in the fridge, a couple of years after expiration date TMX and D100 will be OK, which means "useable, with only small adjustments to your technique". You might find, if you did rigorous tests, an increase in fog level which would have the effect of decreasing film speed and contrast.

TMZ goes off much more quickly than TMX.

-- Alan Gibson (gibson.al@mail.dec.com), November 03, 1997.

RE: Response to Expiration dates

Faster films always go bad more quickly. The results of using B/W film long after the expiration date is similar to the effect of an airport X-Ray machine on the film.

Although film is not very sinsitive to heat (not NEARLY as it is to light), heat will slowly expose the film. This will fog the background and reduce contrast. I've heard that it will also INCREASE film speed, although this will be negligible.

Freezing the film will extend its shelf life into the next ice age for all intents and purposes, and referigeration is also very good.

One thing to note, cold film becomes brittle, and must be warmed up for a few hours before using, or else it will crinkle and have damage from static.

Here's a question I have for someone who may know the answer:

Film can be exposed by just about any form of electro-magnetic radiation. This includes light, heat, X-Rays, IR, UV, etc.

Can cosmic rays also slowly expose film over time, and would film life then be shortened in high altitude location like Denver, where exposure to Cosmic rays is much higher than at sea level?

-- Robert Litman (litman@goplay.com), November 05, 1997.

Yes, cosmic rays do fog film.

I read somewhere that some test strips (Kodak?), pre-exposed film used for moitoring development processes, are stored in disused mines until required.

Yes, don't put cold films directly into cameras: it will nbe brittle, and liable to snap. If it's been in the fridge, an hour or two at room temperature will do it. If frozen, leave it to thaw overnight.

Only put sealed films in the freezer, or you might get ice crystals forming.

-- Alan Gibson (gibson.al@mail.dec.com), November 06, 1997.