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Discussion in 'B&W: Film, Paper, Chemistry' started by Woolliscroft, Jun 28, 2005.
Probably another dumb question, but is it OK to re-freeze defrosted films and paper?
I do it for paper all the time. Just make sure it's all wrapped up.
You can do it, but their vitamins will be lost.
Seriously now, why not ? Freezing them prevents ageing, so it will do it whether it's continuous or not...
I was just wondering whether there might be reticulation effects with film that would magnify with printing?
I have been re freezing my film for years now, with no problems at all, I normally take a couple of bricks of film with me on each outing and what does not get used, goes back into the freezer, I have never noticed any degeneration in the emulsions or problems after I have used them and then made prints.
If one was to take film or paper out of the freezer, then put it back while it was covered with condensation, could possible ice build up cause problems?
Yes, you need to make sure it is out of the freezer long enough for any condensation to disapate, before putting it back in the freeze, I keep all of my film in ziplock type bags, and they have a small silicone packet to absorb moisture, but taking it out, for 15 minutes and then putting it right back in the freezer, is probably not the best thing to do. Its kind of like bringing your camera in out of the cold, you will have condensation on the body that could cause problems.
When I worked in Singapore, Malaysia, Vietnam and Indonesia we looked into this issue fairly closely, for movie film and specifically for 'recans' and short ends. Recans have been loaded into the magazine in case they might be required, then returned to the can entirely unused. Short ends are better known - they are the partially used rolls of film.
In both cases the film has been packed into a bag and then into the can along with some very humid (high relative and absolute humidity) air. The question was: will this cause problems and do we need to use silica gel? We ran through the theory, studied the way in which the moisture moves around as conditions changed and ran a few tests (fairly large sums of money are involved here - not just the value of the film, but the risk of using film that is even slightly damp). Long standing practical experience shows that it is OK, of course, but we thought that it was worth a bit of investigation to see how close to disaster we were.
It isn't an issue at all with film that remains sealed in its original packaging - there is a certain, low, amount of moisture locked in and the conditions outside the sealed container are fairly irrelevant, within limits. There is an issue about the degree of sealing though. The air pressure in the container will change as the temperature changes, and this pressure change may be enough to cause the container to breathe a little. It will breathe in when the container is cooled. Fortunately the air inside a freezer or refrigerator has very low absolute humidity.
Anyway, without going into all the unpleasant thermodynamic details (furnished upon request) we were satisfied that there was no problem re-freezing in this instance, if the film is wrapped in the normal way with little air space in the bag - the bag folded closely around the roll of film. If a short end was wrapped loosely there could be a problem. Including a single pack of silica gel would not guarantee that there would be no problem in the case of a loosely packed film.
So, as long as the film is sealed (and there is very little air sealed in with it) and all the sealing and unsealing operations are done when the film has fully equalised to ambient temperature you can re-freeze film that has been opened in humid conditions. But you knew that already.
IMO, freezing is over kill. Films and papers are good
for a few years when kept at the usual room temperatures.
I've not seen any hard data, who has? I think though the
fridge should be good for another few years. Dan