On Mon, 2 Dec 2019 09:40:28 +0000, nightjar wrote:

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One of the items in a job lot of out-of-date film turned out to be an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.

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you can get some interesting effects from out-of-date film though the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


It is not as straight forward as simply looking at the age. Eastman
Kodak first sold photographic film using cellulose diacetate (aka safety
film) as a base in 1912. Originally only in smaller formats, but by the
1940s, there is a fairly good chance that most photographic film would
be acetate. However, the only way to be sure is to look for the marking
'Safety Film', which should be on the box.

Movie film is easier. Because cellulose diacetate did not meet the
performance standards of the film industry, that continued to use
cellulose nitrate (celluloid) until the introduction of cellulose
triacetate in the early 1950s. OTOH, 16mm and 8mm home movie film has
always used safety film. Eastman Kodak chose 16mm as a size specifically
to prevent 35mm nitrate movie film being split for use in home movies.

Whether or not it is degraded will depend upon how well it has been
stored. The big killers are heat and humidity. Under the right cool and
dry conditions, acetate film can last up to 150 years, but 50 years is
more likely if stored at room temperature and much less if it has been
stored in the wrong conditions. If acetate film smells of vinegar,
degradation has begun.

Aha! I hadn't noticed before, where the label is almost worn out on
the corner are the words "Safety Base."

That's very useful further information too. Thanks!

Further investigation obviously needed here...

Nick