On Mon, 2 Dec 2019 09:18:05 -0000, "michael adams"
mjadams25@ukonline wrote:


"Nick Odell" wrote in message
.. .
One of the items in a job lot of out-of-date film turned out to be an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.

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 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you can get some interesting effects from out-of-date film though the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.

Thanks,

Nick

According to

http://www.hse.gov.uk/pubns/indg469.pdf

quote

Cellulose nitrate was used for 35 mm photographic roll film and
photographic sheets up to about 1940, but it continued to be used
for popular (amateur) formats and aerial photography up to about
1950

/quote

So that cellulose nitrate, about which there are all these
problems was only in use until around 1950. So there is no
real basis for comparison based on experience when using
out of date post 50's film stock which is polymer or acetate
based,

quote

it can start to decompose and become unstable at temperatures
as low as 38 °C, giving off large quantities of poisonous gases,
which could cause an explosion. Warmth and humidity (moisture)
accelerate this decomposition;

/quote

So that if its ever been subject to high temperatures
or humidity at any time during the past 70 years then
it may have started to decompose. While at a guess unless
it was stored under optimal low temperature conditions
throughout, it will probably have started to deteriorate.

quote

How can I tell if my cellulose nitrate film has degraded?
Visual evidence and smell can be used to identify cellulose
nitrate film or negatives that are degrading

/quote

" and smell."

So that possibly without actually opening the box it should
be possible to make a pinhole in the box, in a suitably darkened
environment and have a sniff at a distance, bearing in mind that
any fumes may be toxic.

And given that cellulose nitrate and possibly any gases thus released
are highly flammable this would probably be best attempted out of doors
on a cold night using a torch or portable lamp etc. as a source of
illumination.


michael adams

Thanks, that's very useful. Needless to say I shall not interpret
"Portable Lamp" as one of the paraffin variety :-)

Nick