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COLD STORAGE

COLD STORAGE

A low cost modular based vault construction

This article in the Image Journal was based on a presentation given by Morten Jacobsen of Dancan International as a guest speaker at the EBU Training Seminar dealing with Film in Television Archives held in Sarajevo, on 14-15 April 2000
I have probably seen more film archives on Planet Earth than anybody else, and it is amazing to see that all the brave words and recommendations generated by their organisations, FIAF, FIAT/IFTA, AMIA, Seapaava and more, are in many countries merely words, words and words. And on top of this Kjell Kolstadt from NRK in Oslo has rewritten the old EBU Technical Recommendations to R101-1999. TV Stations face devastating environmental requirements, which range from room temperature to very cold and dry conditions. That is a challenge for the brains at the top floor. When it comes to reality then there is only one law, money. We have now ended the cele-bration of the first 100 years with film and the audience is still clapping. You, the archivists are just left with a splitting headache!
Because it is you that handle the film and have the smell of the day to cope with, which is very similar to that of the salad dressing at dinnertime.

Why is it that this very fragile medium has had so little attention, and what can be done?

A fundraiser is certainly not an archivist and an archivist is not a fundraiser. You have no need for an archivist if you don’t have the funds to keep him busy. It’s as simple as that, and the archivist is still waiting while his films rot away. He sees it, he smells it. Any film archive should have a fundraiser. He is the most important person you can hire. His skills must be very politically orientated. He must be in the habit of walking on polished floors.
Let us begin by looking at this graph to visualize what we are talking about.

Mr. Archivist
please enter the data from your own vaults and get a prediction of expected life of new films. Very discouraging isn’t it? Or are you the happy person?
Of course this does not account for everybody, the happy guy with sophisticated film vaults will just smile and say: ‘ha, ha, come and see my archive’. There is a tendency that the colder the climate the better the vault. Is that because the industrial nations are mostly in colder climates? Yes it is. The richer the country the better the situation, but that should not prevent an archivist from improving his situation.

Power consumption
To maintain a temperature of 50C and a humidity of 30% RH (Relative Humidity) in a vault you need a lot of electricity. Let us work on an example.
The vault is 25 meters x 25 meters = 625m2.
The height is 4,5 meters and the total volume is 2812m3.
Power consumption estimated 90,000 kWH per. year with an outside temperature ranging from 00C to 200C.
This is in Denmark where it never really gets hot or cold.

Compact shelving
In a vault of the above size you can store 13000 features and even more when you increase from 5 to 7 shelves. That is more than double what you can obtain with fixed non-movable shelving.

Power consumption is 7 kW per feature film per year.
Is that cheap or is it possible? Consider your own data and remember that we are in Scandinavia.

The keynote is INSULATION
Whatever climatic condition you live in, even at the North Pole, you have to insulate. You cannot maintain any cli-matic control without insula-tion.

Build your vault like kids build with Lego.
Any room designated as a vault area can be modified for the purpose. It is easy, it is fast and it is cheap.

This is a Mineral Wool Sandwich Element. It is non-flammable according to DIN 4102.

If you want even better insulation then a combination of polyurethane foam coated with high-density mineral wool sheets could be your choice. It is thinner, since polyurethane has a high insulating value, and can be used in vaults where space is more limited. To the right polyurethane foam.

The panels show a profiled tongue and groove system, the so-called ‚snap-in connection system’ that guarantees that the following requirements can be met:

1.interrupted thermal conduction
2.vapour-proof
3.easy to assemble
4.high stability

Look at this corner where the walls meet. The yellow area is polyurethane and at the two pieces of angle hold it together. It is glued with an adhesive sealant system.

How to hold the roof in place

Very simple. Any structure can hold it and this is just one example.

Adapt, reuse, and alter any existing archive
There is absolutely no reason to construct a new building to build a film archive. Adapt the existing premises and save money. Now the technical side.

Scroll compressors

This technology is the latest and most promising. It combines the efficiency and reliability of semi-hermetic technology with low noise levels and significant size advantages. Energy consumption is reduced with glacier compressors by 10% compared to other compressor systems. The noise level is very low and requires no sound proofing to neighboring offices.

Centrifugal fan unit cooler

The cooler is connected to the compressor, which is in the technical room behind the wall. It is definitely an advantage to have the technical room with the compressor, dehumidifier and air cleaner in a room adjacent to the vault and fully insulated in order to minimize distances from the different machines. Everything in order to reduce the electricity bill.

Even air distribution bags
A very simple and cost efficient way of distributing the conditioned air is with air bags. They are simple to mount and prevent hot or cold spots in the vaults.
If they get dirty then you simply replace them with new bags.

High tech heat exchanger

The air-cooled condensers are equipped with a high performance coils and the casing is made in galvanized steel sheet and gray enameled galvanized steel. It must be placed freely to avoid short circuit of air.

Air humidity

We now have cooled down the air to the wanted temperature and are left with a major problem, which is air humidity. We need some basic technical information to understand the phenomenon of humidity, which surrounds us, but cannot be seen, although we certainly feel it.
The ambient air always has a certain content of invisible moisture, i.e. water vapor. There is an upper limit, saturation point, to how much water vapor the air can pick up at a certain temperature. If the moisture adsorption capacity of the air is half used only; the relative humidity is 50%. If the air is entirely saturated, the humidity is 100%. When the temperature goes up, the air can pick up more moisture and the saturation point is shifted to a higher value. Should, instead, the temperature go down, there would be a surplus of moisture, emitted to the surroundings by the air in shape of water. Water vapor condenses.

Well known sights are the dew in the grass, the cold mist on a soft drink bottle, the ‘condensation’ on a cold-water pipe, etc.
The air humidity outdoors is mostly very high. The annual mean value for Paris, for instance, is about 80%. A relative air humidity of 50% feels comfortable to humans. Sometimes the raw chill in the winter is caused by the high relative air humidity for that time of the year.

Why is humidity that important?
The perception of indoor climate is governed mainly by two factors, temperature and humidity. Human beings are sensitive mainly to temperature. Relative humidity is less important. The reverse is true for almost every inanimate object, i.e. relative humidity is of much greater importance than temperature.

Humidity is an important consideration in film and television archives.
Dehumidification methods

There are two main methods for dehumidifying air at atmospheric pressure, i.e. condensation and adsorption.

Condensation
occurs when air is cooled to a temperature below its dew point. Cooling of the air can be achieved by compressor refrigeration. This method works well above 150C and 40% RH.

Adsorbtion
entails the binding of moisture to a hygroscopic material. Latent heat is liberated and the temperature rises. The method works with equal efficiency in all air conditions. Various sorbents are available such as lithium chloride and silica gel, which is employed for dynamic dehumidification.

The continuous process


Air to be dehumidified is blown axially through a rotor whose structure forms narrow air flutes. The walls of the rotor structure are impregnated with lithium chloride or silica gel that adsorbs moisture from the air. The rotor turns very slowly (10.r.p.h). Hot air is blown in the opposite direction through a small sector of the rotor and heats the rotor material and its salt. The adsorbed moisture then evaporates and is evacuated with the air.

Basic version
The process air from the vault comes in and the rotor adsorbs moisture and sends it out to the right as dry air, and back to the vault. That is the operating sector. It uses 270° of the wheel. As the wheel turns slowly it passes the lower 90° section of the wheel and here the air, which is moist, is heated up to 100° C in the reactivation heater and the moist is taken out of the wheel and thrown away as wet air. On larger units you can recover the heat and save 30-40% depending on operational conditions. End of dehumidification.

Air purification and or energy recovery.


The fact is that if you have your vault in an area with high pollution from burning of oil related products like petrol in cars, diesel in lorries and buses and so forth, you have to clean the air. It is called air scrubbing.

The coin has two faces.
On one side you have in your vault a number of films that are suffering from the ‘vinegar syndrome’ for one and they also contain a quantity of residual chemical from the development and treatment.

On the other side you have the polluted air outside.
So, you have to import air from the outside to keep a high level of clean air inside, but the air you import is not clean. You take it to be clean but it is not. Then you mix it with the circulated air. You have to remember that the imported air is in most cases warm and humid and you need energy to cool it and dehumidify that air. That is money spent unnecessarily. Why not re-circulate your air 95% instead of 75%. Think of your energy bill.

The air purification system
This can simply and easily be integrated in the machine room or even in the vault. Think of it, you can also incorporate molecular sieves or silica to adsorb the vinegar from the films and all is done without importing air from the outside.

Pressurising the vault
Talking dark talk? No not at all. It is necessary in order to avoid dirty air penetrating the vault. It is only a few bars above normal level. Consider this when insulating – that is why insulation must be tight in corners and at doors.

Considerations in the vault
Let’s consider that we have built you a nice new vault, which has either been constructed in an existing building, a warehouse you own, and a warehouse you rent, or even in your present vault.

Optimizing space
Shelving is shelving, but quality differs and so does price. Do you wish to have fixed shelving prepared for movable shelving or are you going to take the step right away? Be careful when choosing that there is no wood involved in the construction. Only powder coated steel is acceptable.

This picture is out of a brochure. When you roll the shelf stacks together then you will obtain exactly the opposite of what you should. The films will be locked in a closed environment and the constant ventilation in the vault does not reach the film. You maintain a microclimate due to the shelving and that you don’t want.

Ventilated shelving
There are some manufacturers that have started manufacturing shelving with its sides perforated, and that is the right way to do it. If it were complicated then I would choose the shelves to be perforated, because that is efficient and sufficient. Commonly used in supermarkets.

Ventilated film cans (Create a draft)
It goes hand in hand with theory that films should be ventilated. The Image Permanence Institute and Manchester Metropolitan University stress this point. As we deal with triacetate film we have to fight the ‘vinegar syndrome’ and you simply have to get rid of the vinegar and other gases in the film can. As acetic acid fumes are heavier than air you will have to ensure that the ventilation is near the bottom of the can. Either as holes that can be punched in any can after manufacturing (you can order film cans with holes) or there are a number of ‘socalled’ ventilated cans where the lid has been lifted 1mm so it rests on dots. That is also good, but as mentioned before the fumes are heavier than air. A really ventilated film can must have 4 holes or slots near the button. Two in the front, two in the back. Then you create a draft.

Move all films to the new vault immediately
Why? Because, ‘time out’ is another new phrase in your vocabulary. It is a very important factor to consider from now on. Well described by IPI.

FILM HANDLING
Now, as your films are safe in your new vault, the real work begins. Whatever I told you up to this point is ‘only money’, not time.

Re-canning

Begin with the negatives. They are the most important assets in any archive. Most feature film copies can be ordered from the studio again, but perhaps you are the archive that holds the one and only copy of a given title.

Does the film smell of vinegar?
Your very first reaction when you open a can is the smell, and the smell of vinegar is of course obvious and even if you have caught a cold you can smell it or can you? Vinegar develops long before you can smell it. That is the danger. You simply have to test every single roll of film. If you have 20 rolls in the can, test them with AD-Strips or Danchek.

The AD-Strip gives a reading in 24 hours. Danchek gives a reading in 2 hours.

Follow the instructions given by the manufacturers.
Do not forget to enter the data into your computer. It might not have it designated, but that is the easy part. (It will turn out to be valuable statistics)
If you have films you want to monitor more closely there is the Danchek Control Eye. (www.danchek.com)

Get rid of magnetic tape on acetate base.

It is not argued any more that the 16, 17,5 and 35mm perforated tape, on acetate is the biggest problem. It includes magnetic striped acetate films as well. All tape can be recorded onto another format and it is not a loss. It is a loss if you keep it because the ‘vinegar syndrome’ is contagious.

Spend money on a new core (Bobbin)

The yellow thing you see on the platter is usually made of wood and polystyrene or there may be none at all. Polystyrene is considered among the group of bleeding plasticisers and guess, nobody wants that in his archive. There is a beginning spirit to manufacture cores in polypropylene and that is definitely a step on the way. (Dancore will be manufactured with the same stabilisation technology as Dancan)

Film cans
You have now come to the crucial question of which film can to choose. Should it be another metal tin where the metal is still considered a catalyser for the ‘vinegar syndrome’ or could you move to the coated ‘Kodak’ type metal tins? That is a step forward or should you keep your cardboard, which are just as good as a molecular sieve that has to be changed when saturated?

Or, should you consider changing to plastic.
There is a choice of plastic qualities available from recycled polypropylene to straight from the sack polypropylene or should it be a polypropylene with additives, just like a package of ‘antioxidants’ which protects the can from the free radicals, the peroxides and so forth. (www.dancan.dk/papers)

Discard plastic bags in the can
Thin polyethylene or polypropylene plastic bags has been used for decades to wrap around the film when delivered from the laboratory. It is a habit that is difficult to get away from. First of all the quality of the bag is unknown (not stabilized) and it prevents the film from breathing. There are of course different ‘schools’, different opinions on the use of plastic bags. If, however, the film can is inferior then it might prove better, but if the film has the ‘vinegar syndrome’ then it should certainly not be packed so well.

Discard paper information
All kinds of printed information should not be kept with the film. Clean the box for that and do not forget the 35mm printing step vedge.

Separate sound and picture?
This is first of all a hint to Television Stations. They have for the past 50 years kept their picture and soundtrack in the same box. It was a practical thing to do in the sixties, but it does not count to-day. I know it is a hell of a job to do it and the database will have to register that fact. (The is an alternative which is packing the soundtrack in a specially formulated thick plastic bag (Danbag) with a quantity of silica of the blue gel type. This changes color when saturated and needs to be changed. This is a temporary solution, but keeps the vinegar confined)

Conclusion
Taken local climatic situations into considerations then you have to decide where to begin. If you feel it is more important to reduce the humidity level, well go ahead and do it. You can always add more equipment at any time when money permits and make sure there is room for it right now.

Need help?
If you need assistance in planning and building a new cold storage vault for your film, I am your man!

Morten Jacobsen
Dancan International Sales
Box 308
1501 Copenhagen V
Denmark

Write or email to:

Phone (+45) 40 50 41 80 – Fax (+45) 29 54 88 11

More lectures (papers)
Check it out
Handling actively degrading film – Tools and Products

Addendum
The Gamma Group has published

The Vinegar Syndrome
Prevention, remedies and the use of new technology
The publication has been edited by Enrica Serrani (Cineteca Comune di Bologna)

cineteca.segreteria@comune.bologna.it

Morten Jacobsen
was born in 1938 in Copenhagen, Denmark.
His interest in film started early, and in his teens he used 8mm, Super 8 and 16mm.
In the swirl of his youth masters like Dreyer and Eisenstein made impressions and film clubs widened his horizons, leading to Youth Festivals in Berlin and a prize in 1962 , when the wall had just been built.
Then came a taste for the professional scene, at a time when a cameraman was often a guy picked from the street. Morten moved up to 35mm format and began to make short films.
New ventures came along, such as an encounter with products like brand new plastic film spools and cans from Australia. The Seventies were booming.
Tooling for square film cans led to a range of 16mm Dancans.
In the Eighties, Morten developed an interest in 35mm and film archives and added more tools to his range. Then came the Nineties, the period where the “Vinegar Syndrome” became hot and Danchek was invented. Research projects in England and numerous papers presented in Europe and USA followed. To-day he is considered a specialist in film storage and is always willing to let others benefit from his experience.