Humidity Control

Control of relative humidity is required for preservation of permanent records.

Air Conditioning

Properly controlled air conditioning of the storage area is definitely recommended for the optimum long-term preservation of permanent records. The air should be filtered to remove dust, cleansed of gaseous contaminants, if present, and controlled to the desired relative humidity and temperature. Slightly positive air pressure should be maintained within the storage room or vault. Film should be conditioned to this environment and then placed in containers.

Where air conditioning is not available and high humidities are likely to be present, the humidity of the storage area can be lowered by electrical refrigeration-type dehumidifiers. These are readily available and inexpensive. The storage space should first be vapor-sealed by covering the walls with asphalt or aluminum paint or, better yet, paper-laminated aluminum foil or other water- vapor barriers. Painting the storage area is suggested, but follow the painting precautions.

A humidistat set at the desired level of humidity should be used to control the dehumidifier. The humidity level should be checked frequently with a reliable hygrometer, such as a sling psychrometer. For added protection against short-term moisture effects, such as dehumidifier failure, tape the containers as described in the following section, “Moisture-Tight Containers.”

Dehumidifiers using desiccants should be used with caution. They may create a danger of fine dust particles getting on the film and causing abrasion when the film is used. Also, when some chemical-desiccant particles are trapped in rolls of microfilm, they may form bleached spots. Therefore, inert desiccates should be used, and it is essential that the system be designed so that particulate material cannot enter the storage area. The use of molecular sieve packets is recommended, as this is an efficient desiccant. Chemically pure silica gel may also be used as a desiccant, provided that filtration is used to remove particle layers larger than 0.3 micron. See ANSI/PIMA IT9.11-1998 and ISO 18911- 19985 or their latest revisions.

Moisture-Tight Containers

If humidity control of the storage area is not possible, the storage of film in moisture-tight containers is required to maintain the film’s humidity limits. The film must be conditioned to the required humidity before being sealed in the container. This requires the temporary use of an air-conditioned cabinet or room, or an electrical dehumidifier. Smaller quantities of film can be conditioned for two or three weeks in a desiccator containing activated silica gel, and then removed and quickly sealed.

Only properly sealed metal or glass containers are considered moisture- and gas-proof. They are preferred when long-term air conditioning is not practical, when gaseous impurities may regularly be present, or when low-temperature storage is used.

Plastic boxes, such as Kodak Microfilm Plastic Storage Cartons (CAT No. 108-6867—16 mm; CAT No. 841-8741—35 mm), can be used as protective containers in controlled areas. They provide satisfactory protection against short-term problems of moisture or gaseous impurities, such as might occur with floods, dehumidifier failures, smoke from a fire, or moisture released by insulation (upon exposure to heat) in certain fire-resistant safes and cabinets.

With both metal and plastic containers, all materials (including any gaskets and protective paints or lacquers) must be non-corroding and free of peroxides, reactive fumes, and exudations during storage. Closed containers with friction- type or threaded twist-on lids may require no other seal, but should be tested for imperviousness.

If the container is in an area having the prescribed humidity and known to be free of harmful gases, taping is not required. If these conditions are not met, taping will provide satisfactory protection.

Plastic boxes or cans are preferable, as they provide more insulation in case of fire.

D-31 June 2002

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Kodak D-31 manual Humidity Control, Air Conditioning, Moisture-Tight Containers
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D-31 specifications

Kodak D-31 is a color negative developer that has garnered attention for its unique set of features tailored to meet the demands of both professionals and enthusiasts in the field of photography. Designed primarily for use with color negative films, Kodak D-31 is known for delivering impressive results in terms of color reproduction, contrast, and image sharpness.

One of the standout characteristics of Kodak D-31 is its flexibility in processing various types of color negative films. This developer can be used for a range of ISO sensitivity ratings, making it versatile for different photographic situations. Whether capturing landscapes, portraits, or street photography, D-31 ensures that the vibrant colors and subtle tones of each scene are accurately represented.

The technology behind Kodak D-31 incorporates a balanced mixture of color-forming agents and stabilizers that contribute to its reliability. The developer uses a carefully controlled chemical composition that ensures consistent performance with minimal grain, which is a critical factor for photographers who demand high-quality prints. The result is images that display fine detail and smooth transitions in color, which can be particularly important in post-processing and printing.

Kodak D-31 is designed for easy use, featuring a simple processing workflow that can be followed even by those new to film development. The Developer can be used with standard tanks and is compatible with both manual and automatic processing equipment. This ease of use makes D-31 an excellent choice for educational settings and home darkrooms, as it allows users to focus more on the art of photography rather than the technicalities of the developing process.

An additional advantage of Kodak D-31 is its ability to deliver consistent results across different batches, which is essential for those looking to maintain a cohesive portfolio. Photographers can rest assured that each roll developed will yield similar results, thanks to the high degree of control in the chemical composition and the assurance of quality that Kodak has provided for decades.

In summary, Kodak D-31 stands out as a reliable, versatile, and high-performance color negative developer that is well-suited for a variety of photographic applications. Its thoughtful formulation offers photographers the ability to capture and reproduce color with precision, making it a preferred choice for both hobbyists and seasoned professionals alike. With its blend of technology and ease of use, D-31 continues to be a valuable tool for anyone looking to explore the rich world of color film photography.
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