by Greta Bahnemann
Almost all archives possess some type of photographic collection. Many individuals typically think of “photographs” as plastic-based negatives and slides; but these photographic techniques are relatively recent inventions. Prior to the invention of cellulose nitrate film in 1903, photographic emulsions were made on glass supports. These glass supports are typically referred to as glass plate negatives. The term “glass plate negative” refers to two separate formats: the collodion wet plate negative and the gelatin dry plate. Both of these formats consist of a light sensitive emulsion that is fixed to the glass plate base with a binder.
Dozens of photographic techniques have been used within the past 150 years. Each photographic process possesses its own “unique deterioration characteristics” and each process’s degradation is accelerated by slightly different factors (Northeast Document Conservation Center, 1999, p. 1). Additionally, all photographic processes demand specific storage and exhibition considerations as well as training in the proper handling and care. Glass plate negatives are no exception.