Re: expiration dates on film boxes

----- Original Message -----
From: "Shannon Stoney" <sstoney@pdq.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, October 13, 2005 10:30 AM
Subject: expiration dates on film boxes

> I've been thinking about Dan's idea of the "end of the
> silver era" hypothesis about inconsistent results with
> TXP. I just looked at the two boxes of TXP that I have.
> One was bought at a local camera store and has an
> expiration date of 2/2008. I used this film a couple of
> weeks ago in New Orleans and it performed perfectly. The
> other came from BH PHotovideo and has an expiration date
> of 3/2006. It seems that this box from BH is two years
> older than the other box! I have not used this film yet.
>
> That got me wondering: how is film dated? How long is it
> expected to last? That is, when a sheet of TXP is
> absolutely fresh, right out of the factory, how much into
> the future is it dated? And why would the camera store
> have much fresher film than BH?
>
> --shannon
>

   Kodak's expiration dates seem to be very conservative.
The idea is that the film will perform about the same as
fresh film up to that date even if not stored well. My
experience is that most film lasts well beyond the
expiration date. I have recently been using up some 4x5 film
that is probably at least 15 years old. Some shows some fog
but some does not. The fog is cured by adding a little
bromide to the developer. The main change in most film is
the accumulation of fog. While this has a practical effect
of lowering speed (as does adding bromide or benzotriazole)
contrast seems not to change too much and I generally give
more exposure than the ISO speed calls for anyway. The films
I have been using are Plus-X Pan, T-Max 100 and T-Max 400.
   Unfortunately sheet film does not have edge markings.
Where these exist they are useful in telling if problems are
due to exposure or development errors.
   If you have any of the misbehaving film left I suggest
making a test with it and with a sheet of the newer film.
Develop them together and see if there is a difference.
   If there is none of the old stuff left unexposed try
developing one sheet of your exposed films along with a test
sheet of the newer film. That will at least eliminate the
development technique.
   BTW, I am not enthusiastic about development by
inspection. Some people seem to have success with it but
I've never found it useful. For one thing you really can not
compensate for exposure by changing development. Development
changes contrast. If you vary the development to try to
compensate for an exposure error you will get either too
high or too low contrast. Overexposed negatives are not much
of a problem because modern film has tremendous overexposure
latitude but the ISO method gives just about the minimum
exposure for reasonable shadow detail so there is very
little latitude on the underexposure side.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com