Prolonging the life of unexposed film

Discussion in 'Film and Processing' started by colin_o, Aug 13, 2013.

  1. It's my understanding that the two main things that damage unexposed film are heat and radiation. If stocking up
    on film is becoming more common, then these two factors need to be taken into consideration, so that using film
    past the expiry date on the box does not become a worry. Protecting against heat can be achieved by storing film
    in a fridge or ideally a freezer. But protecting against radiation is not so straightforward. Ideally film would
    be stored far underground, but this is not generally possible. In addition to cold storage, should film also be
    stored in those lead-lined bags that are/were advertised to protect film against airport x-rays? Or would they be
    ineffective against the kind of background radiation that is normally present?
     
  2. Those bags are worthless. The damage comes from cosmic radiation, which is extremely high energy and can pass through many meters of lead (or, depending on the particle, the earth itself). The chance that such a particle will be absorbed by your film is small. More likely is that it gets absorbed by something nearby, which releases a shower of lower energy particles that do get absorbed by film. That causes the fogging.

    Unless you've got a giant salt mine, I think trying to protect against radiation hazards is likely futile.
     
  3. Thanks for the reply Chad. You say that cosmic radiation can pass through many metres of lead making the lead-lined bags useless for cosmic radiation, but do you think they would have any benefit in protecting film from the lower energy particle showers you mention, or would the bags be equally ineffective against these particles?
    Also of related interest is this publication from Kodak that I just came across:
    Film Storage and Handling
     
  4. SCL

    SCL

    Forget about radiation, it is in, on, and around everything and everybody to some extent, and ...the primary issue for film is/was large X-ray machines at airports - which historically delivered short bursts many times what one gets each day. Just keep the film in a fridge, or if you are really paranoid you can rent storage space in former missile silos out west about 300-400 ft below the earth's surface....(just hope there isn't a large granite substrate nearby) :)
     
  5. All you can really control is temperature. For the most part, colder is better, although a few films do NOT like freezing. Many batches of Ektar 25 are destroyed by freezing, crystals form.
    So a freezer is generally better than a refrigerator.
    Be SURE to leave the film in the original vapor-sealed containers. Humidity causes condensation which is deadly.
     
  6. I'm not that paranoid about radiation, but if the simple act of storing film in a lead-lined bag had a definite advantage, then I would have done it. If not (as it seems), then I won't be worrying about it and Ziploc bags will do.
     
  7. SCL

    SCL

    I've known some people who actually take off their luminous dial wristwatches when they shoot, worried that the radiation will affect their film.
     
  8. I wouldn't worry about radiation from watch dials. Radium (which was the primary source for luminous dials) was discontinued from use sometime around 1960. The glow of older watches diminished as the radium 226 alpha emission caused the phosphors to degrade. Later watches used tritium, but they were better sealed and the tritium's fairly short half life means most of them are not giving off much radiation. Most luminous watches today have a phosphorescent coating that glows after light exposure.
     
  9. Lead lined bags MIGHT stop low level radiation, but they make it more likely that a high energy cosmic ray will be absorbed near your film which will do some damage.
    Missile silos won't work. they aren't deep enough and they don't have the right materials.
    Chad was on the right track with the salt mine suggestion. Sodium and chlorine have no common radioactive isotopes so a few hundred feet of sodium chloride is an ideal way to protect film (or anything else) from radiation. A coal mine would be a terrible choice. Radioactive carbon 14 is plentiful in coal.
    The one practical way to deal with radiation is to only store low speed film for very long periods. Radiation sensitivity is ROUGHLY proportional to light sensitivity. I've successfully used K-64 that was frozen for 25 years. Fogging of the blue sensitive emulsion was just beginning to become evident. I've used 320 speed instant film that was frozen for 25 years and it was noticeably fogged.
     

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