On 01/12/2019 21:36, Nick Odell wrote:
One of the items in a job lot of out-of-date film turned out to be an
unopened box of Ilford sheet film which must have been manufactured
between 1942 and 1945. It's the oldest unexposed film I've ever come
across.

What type is it? I recall ageing FP3 being around post war in bulk. I
think by then almost all of the manufacturers were making safety film
from cellulose acetate. Useful timeline for Ilford product chronology:

http://www.photomemorabilia.co.uk/Il...hronology.html

I can't help comparing this to owning an unopened bottle of wine of a
bygone vintage: once it's opened, it's opened and all the mystique is
gone. It might have turned out to be a nice bottle of wine but it
might have been better never to know.

I'm asking uk.d-i-y for some scientific advice. Should I presume that
the base is celluloid, in which case what are the odds that the box
only contains a sticky gloop or crumbled powder? I've heard of ancient
movie film stock spontaneously combusting: is there any danger of that
and are there any specific precautions I should take?

If it is original celluloid as in cellulose nitrate then it should be
kept in a cold dark explosives bunker well away from your property. The
stuff gradually goes unstable with age and long term exposure to heat.

Old celluloid negatives of historically important news images have now
mostly been scanned to archival quality but the originals are kept in
small batches in carefully controlled conditions off site afterwards.
Some of them show slightly alarming signs of deterioration.

It generally just burns incredibly quickly unless confined or provoked
by impact when it may detonate. Basically it is sheets of gun cotton.

Glass plates are much more stable and pose no threat at all (apart from
sharp edges and breaking if you drop them).

If the odds are that the film is viable then I'll probably use it -
you can get some interesting effects from out-of-date film though the
oldest I've used so far only goes back to 1980 and the results I've
had with it have been pretty good. If the chances are pretty hopeless
I'll probably try and preserve the mystique and keep the box and its
secrets intact.

A museum might be interested in it as stock in an old photographic shop.
Wet chemistry developing and printing has become a minority sport today.


--
Regards,
Martin Brown