As a contractor at the Smithsonian Insitution Archives, I work with the photographic collections stored in our cold vault. Among the various photographic formats found there are a particular type of glass plate negatives; gelatin dry plate negatives.
Invented by Richard Leach Maddox in 1871, gelatin dry plate negatives became the most popular form of negative in use from 1880 to 1900. Maddox developed a technique to fix a light-sensitive gelatin emulsion to a glass plate. Previously, photographers used the collodion negative process, which often required them to create portable dark rooms or prepare negatives on site. Gelatin dry plate negatives utilized different sensitizing, fixing, and development solutions that provided faster exposure times, less toxicity, and a significantly easier and less cumbersome production process. With the invention of lightweight flexible film, photographers stopped regularly using the gelatin dry plate negative process, although it is still sometimes used today for highly specialized photography , such as the creation of precise astronomical measurements.
A large number of the Smithsonian Institution Archives' holdings of glass plate negatives (which number circa 20,000) are kept in a special storage facility referred to as the cold vault. The temperature and humidity are controlled and kept low, so when working in the vault it is important to bundle up!
I have been working over the last year to improve the preservation of the glass plate negative collections in the cold vault. The glass plates have been rehoused in specially designed conservation boxes that provide essential support and padding.
While gelatin dry plate negatives tend to have an excellent shelf life, their glass composition makes them fragile. When I discover a broken negative, I piece it back together, digitize it, create metadata for the image and stabilize it in a sink mat.
The gelatin dry plate negatives in the Archives' collections are a rich historical resource and it is a privilege to know that the work I do to stabilize and rehouse them will preserve the negatives for future generations. Be on the look out for my upcoming post that will highlight another photographic format held in the cold vault: lantern slides.
- What Does a Photograph Archivist Do?, The Bigger Picture blog, Smithsonian Institution Archives
- Putting It All Together: The Assembly and Rehousing of Glass Plate Negatives, The Bigger Picture blog, Smithsonian Institution Archives
- Unlocking the Vault, The Bigger Picture blog, Smithsonian Institution Archives
- Accession 11-006 - United States National Museum, Division of Graphic Arts, Photographic Collection, 1860-1960, Smithsonian Institution Archives