Image Formats: Glass Plate Photographs

Artists have been rendering real life scenes through various visual media for millennia, but the creation of still photography by Louis Daguerre in 1837 allowed for the permanent capture of visual information. The daguerreotype process involved exposing a sheet of silver-plated copper to light using a camera, exposing it to mercury vapor, and then rinsing it in chemicals to remove the medium’s sensitivity to light. As new chemicals were discovered throughout the 19th century, the underlying photo medium and light sensitive compounds changed. One popular format for photographs was the glass plate, which had improved optical clarity and were more stable than competing paper-based photographs. However, glass plates are fragile and prone to breaking. Glass plate photographs used both a wet plate collodion process, which used a liquid nitrocellulose solution, and later a dry plate process, which used silver salts suspended in gelatin adhered to the glass surface. Wet plate photographs needed to be developed in a dark room soon after exposure and were popular from the 1850s through the 1880s. In contrast, dry plate photographs are more stable and could be developed long after exposure, making them the more popular photographic process starting in the 1890s and continuing into the era of film.