Microfilm Hazards

Digital archiving has replaced microfilm as the standard for document preservation. Though once the preferred method for archiving, microfilm has proven to be prone to numerous issues that negatively impact the documents that the film was intended to preserve. Detailed here are the most common hazards associated with different types of microfilm. Though many of these issues can be delayed with proper care, they cannot be prevented entirely. Even if you have not noticed any of these issues in your own collection, you should act now to preserve your precious documents. Once begun, these issues only become worse over time.

NITRATE FILM (nitrocellulose): Nitrate film was used up to the late 1930’s. In the United States, only 35mm film was produced with a nitrate process. Most nitrate film has already been replaced because of the dangers associated with it. There is not much microfilm of this type still around.

WARNING: Nitrate film is a serious Fire Hazard and should not be in your collection. Nitrate film is chemically volatile and can spontaneously ignite. Once ignited, nitrate film is extremely difficult to extinguish and can continue burning even when submersed in water. This type of film poses a serious hazard not only to the content on the film but also to the rest of your collection and to your building and its occupants. Motion pictures and x-rays also once used this type of film, and many of both have been lost to fire. Combustion of nitrate film was responsible for the 1926 Dromcolliher cinema tragedy, the Cleveland Clinic fire of 1929, the 1929 Glen Cinema disaster in Scotland, and numerous projection room fires. Nitrate film caught fire so regularly that all projection rooms were required to be fireproofed. There are regulations regarding the use and transport of nitrate film. If you have this type of film in your collection, you should contact your fire department immediately to inquire about having it safely removed.

ACETATE FILM (cellulose triacetate): From the late 1930’s through the 1980’s most microfilm was manufactured with cellulose triacetate. It is by far the most common type of microfilm.

Vinegar Syndrome: As cellulose acetate film ages, it is subject to chemical decay. The degrading film secretes acetic acid, the main ingredient in vinegar. This acid gives off a vinegary odor and damages the film and its contents. The process causes the film to become brittle. The film can shrink, causing a separation of the gelatin emulsion from the film base, known as buckling or channeling. Crystal deposits and bubbles filled with liquid may also appear on the film. Eventually, the film becomes so brittle that it will shatter under even slight tension. Though certain storage condition can slow the onset of vinegar syndrome, there is no known practical way to stop it entirely. All microfilm of this type will degrade in time.

picture of microfilm affected by Vinegar Syndrome

Redox: Short for “reduction-oxidation”, redox is the result of chemicals in the microfilm oxidizing over time. It presents as yellow, orange, or red blemishes on the film. These blemishes can make the images on your microfilm unreadable. Redox is a common problem with cellulose acetate film. Poor storage conditions greatly increases the chance of redox. Storing microfilm in a cool environment with low humidity and keeping the film away from metals and chemicals are good ways to help prevent redox.

Tearing: Acetate film is prone to tearing. The film base is made from cellulose. Though it has the appearance of plastic, it is actually more closely related to paper. Like paper, this type of film has a molecular structure that consists of straight polymer chains that are easy to break. Though this type of microfilm is easy to splice when broken, a tear that goes beyond the edge of the film is likely to ruin any image it transects.

PRESERVATION STANDARD FILM (silver halide): Modern preservation standard microfilm uses a silver halide process on polyester film. This type of film eliminated many of the problems inherent with cellulose acetate film. The polyester base does not tear readily like cellulose, and silver halide is not subject to vinegar syndrome. Though much higher quality than other types of microfilm, this type of film has proven to have problems of its own.

Silvering: As the gelatin emulsion on this type of film degrades, the silver compounds on the film can move, causing them to reflect light differently. The images can develop a silvery appearance or become dark. Silvering becomes worse over time and can greatly affect the quality of the images.

Oxidation: The gelatin emulsion on this type of film deteriorates with age leaving the silver compounds exposed. The silver oxidizes quickly and becomes tarnished, much like silverware. This tarnishing causes the images on the film to yellow and fade over time.

Fungus: Preservation standard microfilm is particularly vulnerable in warm climates with high humidity. These climates create ideal conditions for certain types of fungus. These fungi will eat the gelatin that is used to bind the silver halide to the film, causing the images on the film to be destroyed.

Prevention: The key factor with most issues related to microfilm is storage conditions. Microfilm lasts longest when stored at a low temperature with low relative humidity. Optimal storage conditions are between 35-40 ºF at 30-35% relative humidity. However, even under ideal conditions these issues are not completely preventable. Though proper storage can slow the effects, all microfilm deteriorates over time. Digital conversion remains the best solution for permanently preserving your collection. The earlier your microfilm is converted to a digital medium, the better quality you can expect from your digital images.

Preservation: AMERICAN DIGITAL MEMORIES is dedicated to protecting the history of our great nation. Your local history is American history, and we would like to help you keep it safe. We will scan your 16mm or 35mm microfilm and optimize every image to ensure quality preservation. We specialize in making quality digital conversion simple and affordable with a quality product that will last.