[pure-silver] Re: old film
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 27 Apr 2007 13:46:04 -0700
----- Original Message -----
From: "Shannon Stoney" <sstoney@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, April 27, 2007 1:01 PM
Subject: [pure-silver] old film
Hi, I have a couple of boxes of old film. One box is dated
12/2005 and the other 03/2006. It is 4x5 sheet film. It
has not been refrigerated all of that time; most of the
time it was in a cabinet, but in the air conditioning.
What happens to film as it ages? Does it get more
sensitive, or less? Or anything?
--shannon
I am assuming this is B&W film. Film loses some
sensitivity amd sometimes also contrast, and gets foggy. The
fog comes from a continuation of the "ripening" process the
emulsion undergoes during manufacture. Modern films have
substances in them to reduce or eliminate this effect. Fast
film is more subject to degradation than slow film.
The expiration date on film is the date the film is
expected to deliver the same quality as new film, however,
its not a sharp cut-off and film is usually good well beyond
this date. This film should be virtually the same as new
film. I've used film which was ten years out of date with
good results and some film that was twenty years out by
adding some anti-foggant to the developer and shooting at
about half the rated speed.
Refrigerating film slows down the chemical processes in
the emulsion and extends usable life. However, fast film is
also subject to fogging by cosmic rays and cooling does not
reduce this effect. I will point out that there is some
controversey as to whether the cosmic ray effect actually
takes place.
Very high storage temperatures can cause fogging but
normal room temperatures usually are OK for film life far
beyond the expiration date. Unless your film has been
subjected to very high temperatures in storage it should be
the same as new.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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