Kodak D-31 manual Molecular Sieves, Film, Format, Content

Very low humidities have, in the past, caused film to be brittle. However, film of current manufacture has not been found to exhibit brittleness or breaking tendencies under normal handling, even at relative humidities as low as 15%. Old film that is found to be brittle at low humidity should be reconditioned to a higher humidity before use. One day’s storage is usually sufficient for conditioning a dry 16 mm roll halfway to a higher ambient relative humidity; to bring it to full equilibrium requires about a week. In each case, both sides of the roll should be exposed to the air.

Rate of conditioning a typical safety film from 20% to 50% relative humidity at 21°C (70°F).

Low humidity affects the curl of silver-gelatin film, causing a slight contraction of the emulsion layer and resulting in a slight curl toward that side.

This is generally believed to be an advantage because the concave emulsion surface is better protected against abrasion. However, excessive curl may cause difficulty in focusing images in some microfilm readers. This can be avoided by conditioning the film to a relative humidity of 30-50% before use. The curl of diazo, TPS, and vesicular films is virtually unaffected by humidity.

Film handled at very low humidities may also develop a static charge as it passes through a reader or rewinder. This static charge will attract dust particles that can damage the emulsion by chemical action or physical abrasion. Therefore, it is important that any film handling area be kept clean. If film is kept in a dry storage area, it may be necessary to use the film in an office area of higher humidity to minimize static problems. However, as previously noted, large humidity differences may lead to conditioning problems.

Molecular Sieves

Molecular sieves are capable of absorbing most of the potential film degradation agents such as moisture, oxidants, solvents, and others when kept in close proximity with the films under confined storage.24 Therefore, Eastman Kodak Company recommends the use of molecular sieves with triacetate and polyester-based films to reduce the physical aging of films and increase the longevity of black-and-white images under confined storage. It also prevents ferrotyping (mold/fungal growth on films), as it reduces the moisture content of film.

Tests have shown that molecular sieves prevent vinegar syndrome associated with acetate-based films and micro-blemishes, and arrests the oxidation of silver images due to peroxides and ozone in the atmosphere. Using molecular sieves slows the rate of these degradation reactions under confined storage and thus extends the keeping and longevity of older film collections.

A single molecular sieve packet inserted into the existing flip-top boxes containing microfilm will last for five to seven years, under recommended storage conditions. Microfilm should be inspected periodically to offer an opportunity to replace the molecular sieves.

The sieves must be replaced at some interval, depending on storage conditions. The use of molecular sieves is cited by the American National Standards Institute (ANSI) as another procedure to reduce redox blemishes caused by high humidity conditions and oxidants in the air. For more information or to obtain molecular sieves (listed below), call Multisorb at 1-800-445-9890.

Molecular Sieves

Part No.	Film	Format	Content
41 ag 43	16 mm	3.5 grams	400
41 ag 47	35 mm	7.0 grams	200
41 ag 51	105 mm	12.5 grams	125

With or without molecular sieves, it is very important to follow current industry recommended practices for film storage, such as keeping film under proper temperature and relative humidity conditions. However, placing recommended amounts of molecular sieves inside flip-top boxes will extend the life of the films significantly. This adds additional protection by slowing the deterioration process.

6 D-31 June 2002