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Author Topic: pliability of nitrte,acetate & polyester film stock
Matthew Bailey
Master Film Handler

Posts: 461
From: Port Arthur,TX
Registered: Sep 2000


 - posted 12-08-2001 09:54 PM      Profile for Matthew Bailey   Email Matthew Bailey   Send New Private Message       Edit/Delete Post 
I wondering if Mr. Pytlak can figure this out. What is the pliability
of fliexibility of nitrate,acetate & polyester film stock?
What solvents or proccesses are needed to restore pliability or flexibility to film stock that gets stiff or brittle with age
even under recommended storage & care conditions?

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000


 - posted 12-10-2001 04:44 AM      Profile for Leo Enticknap   Author's Homepage   Email Leo Enticknap   Send New Private Message       Edit/Delete Post 
There was a paper published by Charles Fordyce in the SMPE (as it then was) journal from 1948 with the really catchy title of something like 'Improved Safety Motion Picture Film Base Support'. It is basically announcing the launch of the 'high-acetyl' triacetate base that was introduced to replace nitrate, and contains quite detailed comparative data on the tensile strength of nitrate and the various types of acetate (e.g. acetate butyrate and acetate propionate) then in use. More recently, Dr. Michelle Edge of the chemistry department at Manchester Metropolitan University here in the UK has done a lot of comparative research on the chemistry of nitrate and acetate, with much of it having been published in the Journal of Photographic Science.

The Fordyce paper is very much a sales pitch, intended to convince the industry that with the new triacetate base, Kodak had overcome the problems or durability and brittleness that had prevented the widespread use of safety stocks up to that point. As we know with the benefit of 50 years' hindsight, it worked!

Of course this won't help you with polyester. If John P or anyone else knows of a similar study which compares the physical characteristics of all three using similar criteria (perhaps the Image Permanence Institute has done some research along these lines?), I too would be very interested...

I don't have the precise reference for Fordyce to hand - I have the paper in my files at home and will try to dig it out over the next few days. I'd be happy to scan it and e-mail it to Brad for posting as a download here, but am not sure if this would be an infringement of copyright. Brad?


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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 12-10-2001 09:05 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
The Fordyce paper "Improved Safety Motion Picture Film Support" was published in the October 1948 Journal SMPE, Volume 51, pages 331-349.

Polyester film support was introduced by DuPont in 1955: "Polyester Photographic Film Base", D.R. White, D.J. Glass, E.Meschter and W.R. Holm, Journal SMPTE, December 1955, Volume 64, pages 674-678.

When Agfa-Gevaert was heavily promoting the conversion of 35mm release prints from triacetate to polyester in the early 1990's, they had quite a few presentations and publications.

On March 8, 1994, I presented the results of a study of polyester release prints at the ShoWest conference. It noted concerns with static, print dusting, and the extreme strength of polyester prints. To address those concerns, Kodak developed Kodak VISION Color Print film, which it introduced in 1998.

Kodak's website has information on film base characteristics:
http://www.kodak.com/US/en/motion/support/h1/base.shtml
http://www.kodak.com/US/en/motion/support/h1/base.shtml#characteristics
http://www.kodak.com/US/en/motion/support/h1/base.shtml#other

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000


 - posted 12-10-2001 09:46 AM      Profile for Leo Enticknap   Author's Homepage   Email Leo Enticknap   Send New Private Message       Edit/Delete Post 
You must either have a reference library in your office of which I am highly envious, or a memory of which I am highly envious, or both!

To try and answer Matthew's original query, the only totally reliable known process for dealing with acetate elements that have already decomposed to the point of becoming brittle is to copy them. AFAIK, brittleness is not a characteristic of nitrate decomposition, although shrinkage certainly is. There is a debate going on in archive circles as to whether preservation resources should be channeled into preservation copying or in providing optimal atmospheric conditions to inhibit decomposition. There is no easy answer to this one, especially for collections of varying types of element in varying stages of decomposition.

For more information, see the following (click to go straight to amazon.com order page)

Henry Wilhelm with Carol Brower, The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures (1993).

and

Read, Paul & Mayer, Marc-Paul, The Restoration of Motion Picture Film (2000).


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