Beyond the Book: Photographs - General Overview

Meghan Ryan, Special Collections and Cataloging Librarian, National Louis University

While photographs are not uncommon items to come across in library or archival collections, their intricate chemical composition requires special care beyond the typical preservation environments for libraries and archives. An understanding of Photo processes is an essential step to assess preservation needs. If these needs are not met, deterioration of the image is likely to occur over time. Luckily, there are a few ways to take action to slow down the process of photograph degradation.

In her book, Photographs: Archival Care and Management, Mary Ritzenthaler explains that basic photographic principles are key to understanding how to care for images in your collection. She describes basic concepts such as polarity, base, and process. The base provides support for a light-sensitive emulsion for most images (with the exception of Daguerreotypes and the plain paper process) and is typically made of metal, glass, film or paper, although Ritzenthaler notes that ceramic, leather, and cloth have been used. The emulsions are typically albumen, collodion, and gelatin, and the “most common light-sensitive materials are silver salts (26).” The process refers to the physical developing of an image when light-sensitive emulsion is exposed to a light source.

Identification of the types of images that one may have in their collections will assist with finding the right preservation environment and storage procedures. The Image Permanence Institute has created a guide to photograph identification for processes, and includes common use dates, key identifiers, and descriptions, along with other useful information. Additionally, the North East Document Conservation Center (NEDCC) also has a guide to photograph identification of distinguishing characteristics with examples included.

While preservation environments can vary for each process, there are a few general guidelines. Relative humidity is the “single most important agent and the key to the preservation of photographs” as well as higher temperatures, which can cause chemical reactions to occur more rapidly, resulting in degradation (Hunter pg. 291).  Other contributing factors to deterioration include light, pollution, and improper handling. In poor storage enclosures, where the outside environment is allowed to bypass protections, many of these factors can impact the life of the photograph.

Whether at a larger institution, or a smaller institution with fewer resources, there are actions that can be taken to counter potential threats to a photograph. The NEDCC suggests that temperature should be set at 70 or below, while relative humidity should be kept between 30-50%. In addition to proper environmental conditions, protective enclosures are critical to maintaining photograph collections and there are many to many to consider. The NEDCC put together an informative and robust guide that describes the options for various materials and the importance of using enclosures that have passed the Photographic Activity Test (PAT).

There are other low-cost measures that can be taken, as Mary Ritzenthaler describes various actions (207):

•    Evaluate and improve handling procedures
•    Incorporate preservation assessment procedures into existing archival functions
•    Monitor environmental conditions and prioritize needs
•    Improve housekeeping practices
•    Review and improve exhibition and loan policies
•    Initiate a regular inspection plan for all photographic materials to identify preservation needs
•    Isolate unstable film and potentially contaminated photographs and provide appropriate segregated storage
•    Develop an emergency response plan

The topic of photograph preservation is expansive, and each institution has its own unique collections. Photographic preservation is not a one size fits all preservation strategy.

References and Resources:

Hunter, Gregory. Developing and Maintaining Practical Archives.  Neal-Shuman Publishers, Inc., 2003.

Image Permanence Institute

Northeast Document Conservation Center

Ritzenthaler, Mary Lynn. Photographs: Archival Care and Management. Society of American Archivists, 2006.

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