Some Basics of Photograph Preservation
Causes of Deterioration
Photographic images often show signs of deterioration, which is usually the result of
- the chemical makeup of individual photographs and/or
- the environment in which photographs reside.
Select Stable Photographs
Black-and-white photographs are more permanent than color images, and is the medium of choice when long-term stability is an objective. Even among color images, however, variations in permanence exist. Kodachrome slide film is a particularly stable color film for long-term dark storage. The quality of photographic processing is also a factor in permanence. Proper photographic processing and thorough removal of chemicals during the final wash are particularly important.
Make a Safe Environment
Proper storage conditions are essential for photograph preservation. A modest investment in archival storage supplies and attention to overall environmental conditions greatly enhances the life of most images.
High temperature and humidity are damaging, as are fluctuations in temperature and humidity. A consistent relative humidity of 40 percent and temperature of 60 to 70 degrees Fahrenheit are reasonable. Exposure to light contributes to image degradation. Ultraviolet light, a major component of sunlight and fluorescent light, is especially harmful. Photographic copies rather than originals are best for long-term display purposes. Photographs are susceptible to damage from fingerprints, tape, glue, ink, rubber bands, paper clips, and various airborne pollutants such as dust and chemical fumes.
Chemically inert storage containers are a preservation necessity. Enclosures designated as “acid-free” are not necessarily safe for photographs. Any material that comes in direct contact with a photographic emulsion should pass the Photographic Activities Test (PAT). “Storage Enclosures for Photographic Materials,” an excellent technical leaflet published by the Northeast Document Conservation Center, details many of the issues in an easy-to-understand article and provides a list of product suppliers.
Metal shelves with a baked enamel finish are acceptable for holding photograph collections. Avoid the use of cabinets or shelves made of wood, particle board, or press board. Actively used collections should be stored in boxes rather than file cabinets as considerable opening and closing of drawers may cause surface abrasions on the photographic emulsions.
Duplicate Deteriorating Photographs
Make high-quality photographic copy negatives, preferable 4 x 5 inches, of photographs that show signs of fading or discoloration. Fewer photographic labs or studios offer this service due to the emergence of digital technologies, and scanning is rapidly supplanting copy photography. Make duplicate negatives that appear discolored, warped, wavy, or brittle; this process, however, is a highly technical procedure, so employ a conservation facility that specializes in negative duplication.
For More Information
- National Archives, Preservation
- American Institute of Conservation, Photographic Materials Group
- Conservation OnLine (CoOL)
- Northeast Document Conservation Center (not-for-profit conservation lab in Andover, MA)
- HFGroup ECSConservation (commercial conservation lab with a regional office inn Greensboro, NC)