This section explains how to store raw film stock and exposed but unprocessed film. This chart summarizes optimum storage conditions.

Raw Stock in Original Package
Temperature
In general, the lower the temperature at which a film is stored, the slower will be its rate of sensitometric change during aging. For periods up to six months, motion picture raw stock should be stored at a temperature of 13^oC (55^oF) or lower during the entire storage period if optimum film properties are to be retained.

Raw stock should be stored at -18^o to -23^oC (0^o to -IO^oF) if it must be kept longer than six months or if the film is intended for a critical use that requires uniforrn results. Sensitometric change cannot be prevented by such storage, but it will be minimized.

IMPORTANT: After removing a package of raw stock from cold storage, allow it to warm up to room temperature (70^oF +/- 5^oF) before opening the can. This will prevent telescoping of the roll during handling because of cold-induced looseness between the layers and will prevent moisture condensation and spotting of the film.

Radiation
Do not store or ship raw stock near X-ray sources or other radioactive materials. Some scanning devices used by postal authorities and airlines may fog raw stock. Take special storage precautions in hospitals, industrial plants, and laboratories where radioactive materials are in use. Label packages of unprocessed films that must be mailed across international borders: "Contents: Unprocessed photographic film. Please do not X-ray."

Gases and Vapors
Gases (such as formaldehyde, hydrogen sulfide, sulfur dioxide, ammonia, illuminating gas, engine exhaust) and vapors (from solvents, mothballs, cleaners, turpentine, mildew and fungus preventives, and mercury) can change the sensitivity of photographic emulsions. The cans in which motion picture film is packaged provide protection against some gases, but others can slowly penetrate the adhesive tape seal. Keep film away from any such contamination-for example, closets or drawers that contain mothballs-otherwise, desensitization of the silver halide grains or chemical fogging can occur.

Relative Humidity
Since a small amount of vapor leakage through the closure of a taped can is unavoidable, give motion picture films additional water-vapor protection if they are to be kept longer than a month in an area having high relative humidity (70 percent or higher), such as home refrigerators or damp basements. Protect unopened rolls by tightly sealing them in a second plastic container or can.

NOTE: It is the relative humidity, not the absolute humidity, that determines the moisture content of film. Relative humidity is best measured with a sling psychrometer. In a small storage chamber, a humidity indicator, such as those sold for home use, is satisfactory.

Handling
Storage rooms for motion-picture raw stock should be designed so that accidental flooding from storms, water pipes, or sewers cannot damage the product. Store all film at least 15 cm(6in.)off the floor.

Construct and insulate rooms that are artificially cooled so that moisture does not condense on the walls. If the building itself is not fireproof, install sprinklers. As indicated, control of relative humidity below 70 percent is not critical as long as the film cans remain sealed. Maintain the temperature as  uniform as possible throughout the storage room by means of adequate air circulation so that sensitometric properties remain consistent, roll to roll.

Do not store film near heating pipes or in the line of sunlight coming through a window, regardless of whether the room is cool or not.

Unprocessed Film before and after Exposure
General Concerns
Once you open the original package, the film is no longer protected from high relative humidities that can cause undesirable changes. Exposed footage is even more vulnerable to the effects of humidity and temperature. Therefore, process film as soon as possible after exposure.

Temperature
Protect film in original packages or loaded in cameras, cartridges, magazines, on reels, and in carrying cases from direct sunlight and never leave film in closed spaces that may trap heat. The temperatures in closed automobiles, parked airplanes, or the holds of ships, for example, can easily reach 60^oC (140^oF) or more. A few hours under these conditions, either before or afer exposure, can severely affect the quality of the film. If processing facilities are not immediately available, store exposed films at -18^oC (O^oF).

Gases and Radiation
Keep films away from the harmful gases and radiation mentioned earlier.

Relative Humidity
When handling motion-picture film in high relative humidities, it is much easier to prevent excessive moisture take-up than it is to remove it. If there are delays of a day or more in shooting, remove the magazine containing partially used film from the camera and place it in a moisture-tight dry chamber. This prevents any absorption of moisture by the film during the holding period. Immediately after exposure, return the film to its can and retape it to prevent any increase in moisture content over that picked up during actual exposure. Moisture leakage into a taped can is more serious when the can contains only a small quantity of film. When these circumstances exist, seal as many rolls as possible in a second moisture- resistant container.

Handling
Handle the film strand only by the edges to avoid localized changes in film sensitivity caused by fingerprints. Folding and crimping the film also introduces local changes in sensitivity. Keep the surfaces that the film travels over clean to prevent scratching of the film's base or emulsion.

A more detailed discussion of long-term storage may be found in The Book of Film Care, KODAK Publication No. H-23.