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Thread: Film base

  1. #11

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    Quote Originally Posted by Emulsion View Post
    Another form of photographic base that could potentially be used in a camera is
    paper!

    -Superior archival properties
    -Can be scanned with new technology
    -Inexpensive

    Emulsion.
    Yeah, you are totally correct; I forgot about that!

    It WAS actually used by the Kinora amateur motion picture camera in the 1910's. (see here http://courses.ncssm.edu/gallery/col.../exhibit05.htm)

    The camera used a friction escapement, no perfs, and the resulting paper negative was oiled, contact printed onto another band of photo paper to make the positive and then cut out each frame with a die to make a circular flip book that mounted on hand cranked base with a stereoopticon-type viewer.

    If you think about it in those terms, paper IS probably the most stable base with a close second in nitrate...

  2. #12
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    Quote Originally Posted by Kino View Post
    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...

    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.
    Kino;

    Just as cellulose acetate has the vinegar effect, cellulose nitrate has the "nitrate" effect and for the same reason. Cellulose nitrate is (IIRC) guncotton, a close analog of nitroglycerine, but more stable.

    And finally, the film in a can is in an enclosed space. A stack of cellulose nitrate films can explode if one begins to burn or is overheated. After all, they are in an enclosed space, the can, and are in an oxygen poor environment.

    Nitrocellulose was designed to burn in the absence of oxygen and to explode in confined spaces. That is the nature of this beast.

    The generic chemical family is "nitroglycerine", "nitrocellulose" and "tri-nitro toluene". The first is a liquid at room temperature, the second and third are solids. All are similar in properties being flammable and explosive and somewhat unstable (to say the least).

    So, even if I could get a stable film base, I would not want to have it around or store it.

    PE

  3. #13

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    Quote Originally Posted by Photo Engineer View Post
    Kino;

    Just as cellulose acetate has the vinegar effect, cellulose nitrate has the "nitrate" effect and for the same reason. Cellulose nitrate is (IIRC) guncotton, a close analog of nitroglycerine, but more stable.

    And finally, the film in a can is in an enclosed space. A stack of cellulose nitrate films can explode if one begins to burn or is overheated. After all, they are in an enclosed space, the can, and are in an oxygen poor environment.

    Nitrocellulose was designed to burn in the absence of oxygen and to explode in confined spaces. That is the nature of this beast.

    The generic chemical family is "nitroglycerine", "nitrocellulose" and "tri-nitro toluene". The first is a liquid at room temperature, the second and third are solids. All are similar in properties being flammable and explosive and somewhat unstable (to say the least).

    So, even if I could get a stable film base, I would not want to have it around or store it.

    PE
    Not advocating the return by any means, but it does have the best record of flexible film bases, ever.

    Think of it as plastic gasoline in your camera...


  4. #14

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    Quote Originally Posted by DanielOB View Post
    ...As I can understand Acetate base is what we get with B&W films, 35mm to 4x5"...
    35mm and 120/220, not 4x5". While there may be an arcane exception or two, black and white sheet film today is coated on polyester base. There are also a few roll films on polyester, but not from the "big three" manufacturers.

    Until recently a few color sheet films were still on acetate, but most I'm aware of have been transitioned to polyester too.

  5. #15

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    I am trying to think of a single type of film still available off the shelf that is acetate and cannot.

    You can special order acetate from Kodak in motion picture emulsions, but you have to buy 100,000 feet minimum if there are no remaining stocks ...

  6. #16

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    Quote Originally Posted by ath View Post
    The firebrigade of Laxenburg / Austria investigating the possibilities to extinguish burning nitrofilm in 1965: http://video.google.de/videoplay?doc...arch&plindex=1
    Kind of like a motion picture version of Fahrenheit 451.

  7. #17

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    yum! Nitrate soup!

  8. #18
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    If I'm following this correctly, then, fp4+, hp5+ etc. are on a triacetate base in roll film and on a polyester base if sheet film? If there are advantages to polyester, why hasn't everything transitioned to it?
    Charles Hohenstein

  9. #19

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    Probably because of back-stock. Simon?

  10. #20
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    First, nitrocellulose is unstable to some extent and subject to attack by many agents. See this: http://sciencelinks.jp/j-east/articl...03A0122159.php for a minor comment on the fact.

    As for uses of acetate and polyester as film supports, there is a degree of dimensional stability gained with polyester, along with increased expense, so it is used on sheet films. The most prominent use was in dye transfer matrix films which must be exceedingly stable to changes in size. It is also used in the printing industry.

    There is a difference in static electricity build up, coatability, and tensile strength. Thus, you can coat on triacetate with a solvent wash and then the emulsion, but polyester requires pretreatment with a corona discharge before it will accept a coating.

    God forbid that a polyester coating jam in a coating machine let alone a high speed motion picture camera. I have seen high speed motion picture cameras with the sprocket gears broken off when the camera jammed while running estar based film. Same thing could happen in a film coating machine at high speed. The entire machine could be out of action until extensive repairs were carried out. The film just will not rip and therefore the inertia of high speed transport causes binds and kinks of 'an indestructable object' which then tears the machine up rather badly.

    PE

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