Preparing film for long term storage in freezer?

[Ben Klesc]

For those wondering if it is really worth freezing over just putting in the fridge. Yes but it depends! If we are talking fresh acetate film no. If we are talking acetate film which has already degraded, than it’s absolutely essential.

Just taking a look at the graph. The average domestic fridge without humidity control is 60% inside. At 40 degrees f fridge temperatures you are getting an extra 20 years out of your old acetates.



Drop the temps to 0 degrees and you’ve just extended the film indefinitely. *Keep in mind degraded film is film which has already spent it's entire life at room temperature. Freezing is the only method which extends its life.



In my case I am freezing my films which have developed vinegar syndrome. Dropping to 0 degrees is a very good way to stopping vinegar syndrome over just using molecular sieves from Kodak. I hope to extend the life of my collection at least another 40 years while I have time archive them all and build my studio setup over the next decade.

[Ben Klesc]

This is all trial and error. Well I learned a very valuable and important lesson today about how freezers work.

If you are going to cold storage any archival material, never use a side loading freezer. Always use a top loading freezer. In the middle of the night one of the films slid a little, tapped the freezer door and popped it open slightly. When I woke up this morning my entire collection of 200 films was drenched including inside which had built up major condensation. The metal covers were soaked and ice crystals formed all over it. I had to walk them up one by one two flights of stairs to an open fridge to prevent frost from forming on the film. I will have to buy new bags, new archival tape, and relabel everything. I am drying off all film next to the dehumidifier for the next week before I seal it again.

This time I will also be using oxygen absorbers in the event that power is lost so frost won’t happen in a sealed bag. It turns out unlike silica moisture packets, oxygen absorbers never expire so it won't react badly to leaving them sealed in a bag for a decade until I can get to them. This was sort of a good thing that happened because now I will be using the ones that come with them. Museums that have cold storage have entire rooms that are kept at freezing temps. Definitely invest in a good chest freezer with four sides so gravity works in your favor, not an old beat up fridge meant for food. As a fridge ages it also loses its ability to maintain a proper seal and you will have increased moisture. Luckily no major damage occurred to the film itself.

[Ben Klesc]

Welp I'm back with a final update on the project.

I was determined to figure out on how I should approach silica gel packets and oxygen absorbers before I reseal and freeze them. I came to the conclusion after speaking with Indiana University film school.

DO NOT, I repeat, do not use oxygen absorbers sealed inside bags of film. It turns out OAPs do carry moisture inside of them that is necessary to sustain the oxidation reaction. I took a humidity gauge and sealed it in a bag with one packet, and it reached as high as 80% humidity. Also you cannot use silica desiccants with oxygen absorbers. “Desiccants reduce relative humidity to very low levels, which will adversely affect your absorber’s ability to carry out its mission.”

OAPs also do not work in freezing temps so to do its job it has to be left at room temps for at least 48 hours. So then what about desiccants? I looked into silica gel. Silica Gel will continue to absorb moisture even below the freezing point. However they do expire after one year, and I plan on long term storage 10+ years so that wouldn’t work.

So I decided to just bite the bullet, not to take the easy way out and bought a vacuum sealer with mylar bags to suck excess air out of the bags to prevent ice from forming. The ziploc brand vacuum bags with the holes in them don’t keep their seal over extended periods of time so this is vastly superior. I then purchased an upright commercial freezer, with Damprid moisture buckets that last around a year. I also dabbed petroleum jelly around the seals because they weren't tight enough straight out of the box.

*The freezer itself has manual defrost and not automatic. Very important. If I ever end up needing to defrost in a few years I would take film and put them into another freezer. It would be a wet mess otherwise and humidity central.

Humidity is water “dissolved” in the air, sort of like the way salt dissolves in water. Below freezing (32F/0C) liquid water turns solid: to ice. But water dissolved in air (humidity) is not liquid, it’s a vapor. It doesn’t freeze, it stays combined with the air. Interestingly enough, though, how much water can be carried as vapor in the air depends on the temperature of the air. Warm air can hold more water than colder air. As the air cools the moisture condenses out, as dew, or fog, or rain, depending on conditions. At freezing temperatures the air is actually pretty dry, even when it’s saturated. (Which is why dry air is often a problem in homes in cold climates.)

If I had to do it all over again I would have bought mylar bags specifically meant for vacuum sealing. I ended up using a textured plastic inserted into the bag to get it to work, and then used a block of wood to quickly shut it and iron it and it worked pretty well. Just more time consuming. I could get ten done in one hour. It involves taping canister shut with PH neutral tape. Vacuum sealing and ironing bag. Putting in staging area of fridge for two days. Then moving it over to the freezer.

[Osi Osgood]

This really is a n excellent series of posts and one of the very reasons for an 8mm forum in the first place.

[Ben Klesc]

This really is a n excellent series of posts and one of the very reasons for an 8mm forum in the first place.

Thank you for the kind words. When I started this project I actually thought there would be a lot more info already out there.

It turns out we are a very rare breed of people. I can say for certain the life of my color acetates which date back to the 1930s will be significantly extended. It will give me a lot more time now to invest in my 4K/6K scanning setup and build the shop.

All together counting I have around 70,000 feet of film. Once it's scanned it will be shared with the world. I plan on adding sound effects to the film. It's going to make a fun project once I can really get the ball rolling. Once I do get it rolling I will be happy to accept film in the mail and digitize other people's collections free of charge.

It really is an effort at this point to archive and save the history we have left. Acetates from WWII era are reaching the end of their life. Luckily the freezing should significantly prolong the and halt any further degradation of VS syndrome.

[Ben Klesc]

Here is a sneak peak of the project just taken with my cellphone over the projector screen.

That is 16mm Kodachrome from late 1930s. It still amazes me how well the old Kodas can hold up.

Full res: https://flic.kr/s/aHBqjzvSe2

[Ben Klesc]

Right now I'm debating a professional in the field who claims that freezing films causes significant damage, even though it is recommended by Rochester Film School (Image Permanence Institute), Indiana University, and Amherst College archives for nitrates and acetates. He informed me that "no one freezes film in the archival industry" and that freezing film "ruins the base of older more fragile films." When I informed him of the vault below he did not believe it existed.

He also claimed that film "continues to offgass" even in frozen temps (which I disagree with), and that sealing them will cause film to degrade even faster. This goes against most everything I have researched. The entire point of freezing is that it stops all further degradation and chemical breakdown prolong life centuries. It also allows you to store at higher humidity levels.

So the Library Of Congress does not freeze their films. They keep acetates at 40 degrees f. However they also control the humidity. The warmer it is, the lower the humidity has to be. Lowering the temps allow you to significantly increase moisture levels. It's very hard to keep above freezing cool temps and humidity low at the same time, outside of a large industrial vault. Which is why it's not recommended you try it at home. I also have gallons of Vitafilm ready at disposal.

More or less 20-30% humidity @ 40 degrees is just as effective as 50-60% @ 10-20 degrees. Good luck with that though.

So after the winter break when the college opens up again, I will be visiting them again to probe them on these further questions. Based on all of the literature I have read, and archival institutions I have visited I am not concerned.

Example of pro freezer vaults...

Indiana Film School (led by Andy Uhrich): https://blogs.libraries.indiana.edu/...XDyUfBPB9fpKOU

Amherst Film School: https://consecratedeminence.wordpres...4gCncyuLvafx58

*Amherst notes they freeze them because "our vaults are not humidity controlled".

[Ben Klesc]

This will be the final update of the year. A Happy New Year to everyone.

I spoke with Steve Greene, an archivist at the Library Of Congress. He told me this.

"Good plan to get these in cold storage. Freezing isn't particularly "controversial" in the moving image sector of Archives. Internationally, many film institutes freeze with vacuum sealing and molecular sieves: Denmark, Taiwan ... Any "risks" (particularly that of embrittlement of the film base) rapidly evaporate in comparison to the concerns caused by advanced vinegar syndrome. Also the concern about using neutral or buffered containers and adhesive carriers seems misplaced, considering the inherent vice of the chemistry of cellulose acetate, which creates its own acid. It is true that hermetically sealing film is probably counter productive. If you're planning for a film vault, the cost of specifying filtering systems (and media) that pass the air through molecular sieves (aka: xeolite media) is a minuscule addition to the fixed costs. Otherwise, your correspondent seems a bit out of the mainstream. Advice from non-film conservationists should always be welcome, never accepted uncritically!"