As I knows there are two differnrt film bases: Acetate and ???
Film base can aslo dictate how long the neg will survive....
Can anyone say more about kind of film bases found in 35mm, roll film, and 4x5" film.
I am interseted to learn kinds in current productrion and what differnce they make. Particularly I would like to learn more aboult Ilford and (former) Agfa APX films.
Thanks for your time
Originally Posted by DanielOB
I don't know anything about their relative keeping properties though.
There are three types of film base that have been commonly used.
(1) The first is Cellulose Nitrate. This is HIGHLY flammable and has long since been discontinued.
(2) The second is acetate. Acetate deteriorates over time and gives off acetic acid (vinegar). Most still and motion picture camera film is acetate. Film archives all over the world battle to conserve acetate film base.....a significant issue.
(3) The third type of film base is mostly used for 35mm motion picture prints. The film that is projected at most cinemas is polyester or Estar. Acetate is easy to tear whilst polyester/estar is almost impossible. There are problems with polyester as it is so strong that it can damage the projector mechanism if a problem occurs....it doesn't easily snap. There are also coating and static electricity issues with polyester. The film manufactures have overcome the latter two issues. Polyester is reputed to have far better archival properties than acetate.
Hope this helps.
Thanks guys for your time. As I can understand Acetate base is what we get with B&W films, 35mm to 4x5". I have particular interest in Ilford Delta, HP-5, and Pan-F, and AGFA 35 mm films (I still have a lot of them).
There is Diacetate and Triacetate. The older diacetate, used mostly in non-professional films during the nitrate era, was more prone to vinegaring than the more recent triacetate base.
* Mono acetate
Only the Triacetate and polyester are still made in any meaningful quantities.
Nitrate base has the best record for longevity; over 100 years.
Polyester currently has the vote for best archival properties; all forms of acetate suffer from vinegar syndrome eventually.
Originally Posted by Kino
I have been told that the nitrate base was plagued by yellowing and brittleness. Many of the films cannot be viewed or projected except in glass holders or one frame at a time.
The yellowing is release of NO2 and N2O4 which yellows the image and also etches silver.
Of course, they are very explosive and become more so with time. Storage in an inert atmosphere more or less fixes the problem, but who can do that outside of a museum.
Not really unless they have been stored in exceptionally bad conditions; some prints or negatives MIGHT be plagued by this, but I never saw that problem more than once or twice in my 13 years of handling Nitrate at the LOC and we had 130 million feet of the stuff...
Originally Posted by Photo Engineer
Now, ferrotyping and silvering are pretty common, as are spoke set and other physical problems, but those come from out gassing of the base for the most part.
The original negative to "the Great Train Robbery" (1903) by Thomas Edison, D by E.S. Porter, is still easily run through a modern contact printer to make new prints from it.
The film stock itself is not explosive, it is inflammable, burns rapidly and gives off hydrogen, oxegen, nitric acid and phosgene (to name a few gases), but the explosive nature comes only when ignited in a confined space where the gas can accumulate in an oxegen poor environment.
Once the film burns enough to liberate enough oxegen to cause "over flash" it explodes.
Please note that the base will burn under water; you cannot put it out once it starts burning...
There have been reports of spontaneous combustion at temperatures as low as 120 F in tightly sealed containers, but the film does not "sweat nitroglycerin" as I have heard rumored.
Another form of photographic base that could potentially be used in a camera is
-Superior archival properties
-Can be scanned with new technology
The firebrigade of Laxenburg / Austria investigating the possibilities to extinguish burning nitrofilm in 1965: http://video.google.de/videoplay?doc...arch&plindex=1