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  1. #21
    StoneNYC's Avatar
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    Quote Originally Posted by OzJohn View Post
    Well it's a crook day when you don't learn something new. I've not, until now, heard of vinegared film and I've always understood acetate film to be very durable. If this happens to processed negatives as well as unprocessed stock, does it not cast some doubt upon the generally accepted archival properties of film? OzJohn
    I think this is film stored improperly in hot and humid locations that can degrade it, and digital hard drives degrade MUCH sooner, 10 years from now tons of corruption and lost images on the same drive, if you COPY the files, and make multiple backups theoretically they will sustain longer, if disaster doesn't strike (like an EMP hitting the US... ). This is 45 year old film, not well stored... still probably "USEABLE" and would expose an image I would guess, I might try cutting a piece and sticking it my crappy back that I never use except for experiments such as this... but, again, why bother, if I can't use the entire roll...

    I shall endeavor to move forward, not be stuck in the past...

  2. #22
    AgX
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    Quote Originally Posted by OzJohn View Post
    Well it's a crook day when you don't learn something new. I've not, until now, heard of vinegared film and I've always understood acetate film to be very durable. If this happens to processed negatives as well as unprocessed stock, does it not cast some doubt upon the generally accepted archival properties of film? OzJohn
    This is part of the long going discussion, not necessarily here at Apug, about longevity of photographic films. However here at Apug discussing acetate versus PET film base the discussion is rather about the mechanical effects, light-piping etc.

    I should add that the type of storage is of influence. Storing film base totally vented (eg. a piece of sheet film in pasper envelope in cotrast to rooled film in tin tight can) is regasrded as beneficial.


    Concerning smell, I have came across acetate cine film stock badly smeling, however not of acetic acid.
    Film is made from various compounds, part of them just evaporate. This is thus not necessarily a sign of vinegar syndrom.
    Last edited by AgX; 03-11-2013 at 04:31 AM. Click to view previous post history.

  3. #23
    AgX
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    Quote Originally Posted by Photo Engineer View Post
    Don't forget that sheet film does not have to travel over 35mm or 70mm camera parts.

    Also, don't forget that there is the vinegar smell in processed film and raw film stock. The latter is far worse I think.

    PE

    As long as there is no liquid acid involved but vapour only, I assume the corrosive effect negligable under practical circumstances.

  4. #24
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    Quote Originally Posted by AgX View Post
    As long as there is no liquid acid involved but vapour only, I assume the corrosive effect negligable under practical circumstances.
    Do you suspect there would be MORE of an issue deeper in the roll? or actually less deeper in the roll? If I pull out a few feet, and inspect the film for liquid acid of any kind, and don't see any, do you think it could be deeper in? or would the closer contact with oxygen on the outside be more of a risk?.

  5. #25
    AgX
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    I expect more decay in the midst of a packed volume of film. But this is hard to answer from a desk-perspective, and rather should be answered by someone who encounters such films as a routine business, thus as a cine restorer.

    Both, the decay of nitrate as of acetate film base is considered as a self-amplifying process, thus the existance of decay products cranking up further decay.

  6. #26
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    Properly stored acetate-based film should last 50 to 100 years without turning to vinegar. It needs to be kept cool and dry. Not necessarily frozen but below room temperature, at least. If stored in proper conditions using vapor absorbing molecular sieves, acetate film should last 100 years or more. It's only when film is stored under bad conditions that it goes bad.

    Polyester (PET) film stock doesn't have the vinegar problem but it's got its own set of issues.
    It's thinner, which might throw off camera mechanisms that depend on thickness or diameter of a roll. It pipes light through the edges which might cause halation and flare. It's also very strong, virtually impossible to tear. If it gets jammed up in camera mechanisms or projectors, it can cause damage. The camera or projector sprockets won't tear through the sprocket holes like they will on acetate.

    The benefit of poly film, for us at least, would probably be increased longevity. Assuming good storage conditions, it should last 100 to 150 years or more.

    Archivally speaking, film, on its worst day, can last longer than a hard drive on its best day.
    Randy S.

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  7. #27
    AgX
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    The thickness and the lightpiping are characteristics of materials now in use. These are well chosen by the industry with a certain application in mind.

    It would be no technical problem to produce PET base with other characteristics if economical.
    The longevity of PET base is considered much longer than those 150years. But I must admit that longevity studies are tricky.


    How many projectors have you seen torn apart due to the use of PET-based film?

  8. #28
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    I have heard of cameras and coating machines damaged by PET films.

    But, most importantly, once started this process keeps going. So, taking pictures and processing the film won't halt the degradation and thus you will eventually lose your pictures. I would not waste time on this one.

    PE

  9. #29
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    Quote Originally Posted by AgX View Post
    How many projectors have you seen torn apart due to the use of PET-based film?
    Oh, my God! I've got war stories!
    Reader's Digest version: I, personally, have had to rebuild two projectors that were damaged when polyester film got jammed up in them. $2,000-$3,000 worth of repair, each. (Not including lost revenue due to down-time.) I have had to replace several sprockets, rollers or other small parts due to jam-ups. I was told about one of the first incidents of a jam-up with polyester film at my company where the platter system was pulled over on its side by the projector motor. Over 2 miles of film was dumped on the floor.

    If you keep your projectors clean and working properly and, if you pay attention to your work, polyester film presents few problems. But, if you screw up, you can really have a mess on your hands.

    A lot of the newer projectors that were produced had carbon fiber drive gears that were designed to strip out in case of a jam. Replacing the gears is less costly, compared to replacing the whole mechanism. Intermittents (AKA: Geneva movements) must be made of steel and, if you blow one of those up, you're S.O.L!

    Quote Originally Posted by Photo Engineer View Post
    But, most importantly, once started this process keeps going. So, taking pictures and processing the film won't halt the degradation and thus you will eventually lose your pictures. I would not waste time on this one.
    Good point!
    I didn't really think of that.
    No sense in using film that's already over the hill. It will only pick up speed.
    Randy S.

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  10. #30
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    I have not met till now the decomposition of support of film in the undeveloped film.
    Cases of vinegar syndrome for films I have met at the National Film Archive of Romania.
    Decomposition worst case I've seen from support at some magnetic tapes of 35 mm.
    Magnetic tapes were kept in plastic bags and then placed in metal box 300 m.
    The smell of vinegar when they opened the dreaded plastic bags.
    The vinegar syndrome, support of triacetate have various stages of decomposition, finally reaching the film can no longer be used.
    In the case of films undeveloped affected by vinegar syndrome, I think the most important result is the development process.
    Acetic acid formed upon decomposition support (more or less) is a weak acid, but surely will interact with the developer.
    A wash, or better, a solution of sodium carbonate (3-5 g / l) could solve problems acetic acid formed.
    After the solution of sodium carbonate, wash the film and then put it in developer.
    The method of prevention of vinegar syndrome is aeration of film.
    Roll of film (developed) unfolds periodically at low speed.
    For undeveloped films I suggest you find a way to expose them to the air (in a darkroom) for a few minutes or more.
    I do not know how advanced the decomposition of the triacetate (support) you are.
    Acetate suport degradation is autocatalytic reaction.
    Acetate suport degradation is infectious. Infected air from deposits of films may initiate or exacerbate degradation of films - vinegar syndrome.
    Airtight films have a higher risk of accelerating the decomposition of suport of acetate.
    Proposals to keep control vinegar syndrome:
    Maintaining a proper environment leads to improved chemical stability. Low temperatures and dry air reduces the degradation rate.
    Support infected acetate will degrade increasingly faster. Stabilization of degradation -vinegar syndrome - involves improving storage conditions.
    Removal of acetic acid, a byproduct of degradation, decrease the degradation and limits and risk of infection.

    George

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