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Re: [ARSCLIST] Acetate tape discolours tape box

At 10:39 AM 10/18/2006, Bev Lambert wrote:

I have used the A-D strips and have a package, but the general consensus is that they do not work reliably on tapes. I don't recall all of the details that others have observed and someday I will pursue this with IPI, but their focus is film.

As to the date for nitrate film, several online references suggest that Kodak discontinued it in 1951 or 1952 and that it was discontinued worldwide by 1955.

I recall my mentor telling me years ago (he's been dead for years) that when he got back from WWII he threw out all his nitrate negatives as they had started to decay. For amateur purposes, safety film was introduced in the 1930s, I believe.

So, I would suspect that any amateur film (motion or still) from the late 1930s on would be safety film (I believe Kodak never made an amateur nitrate film, but could be wrong on this) and only pro motion picture films used nitrate into the early-mid 1950s. Of course, this is date of manufacture. Obviously films hang around for a long time.

It is my understanding that freezing makes nitrate essentially safe and stops the decay that turns it into nitroglycerine.



Oh yes I forgot to mention that IPI (Image Permanence Institute)
developed a method for detecting the stage of deterioration of acetate
based film.  I dont see why this cant be used with audio tapes as well.
If you contact them (www.imagepermanenceinstitute.org) they will give
you the necessary information.  There is a kit including 250 A-D (acid
detection) strips), instruction guide and a colour reference pencil.
They also sell a  Storage guide for Acetate Film publication. The
process involves putting a little blue strip into each tape package
-box, envelope whatever, leaving it overnight -they tell you how long
depending on the storage temperature- and then comparing the colour of
the strip to the colour bands on the pencil. The amount of colour change
indicates the level of degradation and therfore whether existing storage
conditions are adequate for preservation.
  As to why some more than others according to brand, its hard to say,
as many of the manufacturers are quite proprietory about their
formulations. So, other than the history of storage conditions and
  And for film from the 50s: that is most likely NITRATE, much more
scarey.  Especially moving picture film - by the nature of which it is
rolled tightly against itself, previously in non ventilated metal tins,
and those tins stored close together in small rooms, again without
ventilation..the chemical breakdown creates heat...its literally an
explosive situation. Nitrate is not a stable material, it breaks down
into nitric acid, &/or nitrogen gas!  If someone were to drop a tin of
deteriorated nitrate film in that storage situation, the result could be
an explosion, instantaneous fire igniting the rest of the collection.
Thats not to say all nitrate film is bad- but it needs to be kept under
carefully controlled and monitored conditions, and copied to a more
stable base before deterioration sets in.  Thats why the big
repositories of film in the US have built literally underground bomb
shelter type storage facilities.  You probably know this: the first
moving picture film is on nitrate and  even though they stopped
producing it when acetate was introduced, it was still around of course
and filmmakers used it. Nitrate has a beautiful asthetic quality they
felt they could not get in other types of film-of course its all black
and white. Still photographic negatives have the same history but dont
pose quite the threat because they are small and usually each is
separated by its own enclosure.

Also I neglected to tell you who I am.  I am not a specialist in film,
but had to find out about all these media to advise the archives I work
for on proper storage for their collections. You can find out more from
the Canadian national archives, now called Library Archives Canada, and
large repositories in the US such as Library of Congress and research
institutions such as IPI. They all have web sites with Preservation

Beverley Lambert, Conservator
Provincial Archives at The Rooms
St. John's, Newfoundland & Labrador, Canada
709-757-8057 Fax: 709-757-8031

Richard L. Hess email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.

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