Preservation of the Daguerreotype Collection
Daguerreotypes can be easily damaged. Treatment involves a certain level of risk and should be done under the supervision of a professional conservator.
In 1985, the Library's daguerreotype collection was surveyed and recommendations for conservation treatment were proposed. The Brady daguerreotypes were treated in 1992. The remainder of the collection was treated shortly thereafter. New acquisitions are evaluated for their conservation needs and treated as resources become available. (See Glossary of Terms Used with Daguerreotypes for an explanation of the elements of the daguerreotype.)
The Library received the majority of the Brady daguerreotypes as a gift from the Army War College in 1920. When they arrived, the daguerreotypes were uncased and many did not have cover glasses. The plates were scratched and abraded. They were also discolored from previous cleanings.
The Library's conservators devised a new housing system for the Brady daguerreotypes in consultation with the Library's curatorial staff, photographic conservators from other institutions, and a contemporary daguerreotypist. A functional housing design was developed that also included a presentation mat. The package consists of an inner polypropylene sinkmat. The daguerreotype rests in the sinkmat, and is held in place with Mylar corners. A sheet of glass is placed on both sides of the package. This package is then sealed with Permacel J-Lar 910 tape. A face mat of acid-free matboard is affixed to the outside of the package. In this housing, the entire plate, front and back, can be viewed.
The conservation survey of the Library's cased daguerreotypes revealed two main problems: deteriorating cover glasses and unsealed daguerreotypes. The Library's conservators, in consultation with conservators from other institutions and Library curators, decided to clean and retain the original cover glasses, rather than replace the cover glasses with new glass. (New glass gave a distinctly different feel to the object and was only used when the old glass was cracked or badly damaged.) Since the daguerreotypes are stored in a stable environment, where the temperature and humidity levels are monitored, it is believed that little if any deterioration will occur. A piece of Mylar was placed behind the daguerreotype plate to limit the contact area of the sealing tape. The daguerreotype package was then taped together. The preserver was replaced around the sealed daguerreotype and the daguerreotype package was inserted into its case.