2 NEED FOR PRESERVATION

THESE NEGATIVES were acquired by the National Archives after its creation in 1934. They are primarily collodion negatives, but the collections include some early gelatin plates and copy negatives. Before coming to the Archives, they had been stored in a variety of conditions, often in poor-quality enclosures within storage rooms lacking control of temperature, relative humidity, or atmospheric contaminants. At the Archives they were rejacketed, and reference prints were made available. For many years, however, the original negatives, rather than duplicates, were used to make prints for researchers. This practice resulted in frequent handling of the originals and placed the fragile glass plates at considerable risk.

Custodial archivists and conservators observed other preservation problems associated with these plates. These problems included flaking and softening of image-bearing binder and varnish layers, image discoloration, and development of crystalline or moist deposits on the glass support.

Of the plates involved in this preservation project, most remain in very good condition. All of the negatives in these series have been examined and duplicated, and most have been newly rehoused, topics addressed in later sections of this paper. The plates are stored in a specially renovated storage area equipped with a self-contained air-conditioning system. Approximately 10% of these negatives require special preservation measures, such as custom housing for broken or flaking plates.This project begain in 1983 and continues as resources are made available for its completion.

Knowledge of the constituent materials of permanently valuable archival records is important in determining proper long-term preservation measures. It is necessary to understand the process by which they were made, the materials used in their production, and the manner in which they deteriorate. This knowledge is expecially critical for the large group of historically significant negatives in this preservation project.

The following discussion of the approach to preservation of negatives pertains to a relatively large group of negatives made by the collodion process, all of which have significant historical and artifactual value. Preservation projects that consist of a large or small number of collodion or gelatin glass negatives may be approached similarly in small or large institutions. The resources required to carry out a project of this scope are significant, however, and must be justified by the value of the photographic records involved.