Glass plates were used as supports for photographic negatives before the invention of cellulose nitrate film in the early 1900s. There are two types of glass plate negatives: the collodion wet plate, invented by Frederick Scoff Archer in the 1850s, and the silver gelatin dry plate, developed by Dr. Richard L. Maddox in the 1870s.
Alexander Corner, Calgary, Alberta. 1914-1918 Photographer: Oliver, W.J., Calgary, Alberta. 8”x10” glass plate negative Glenbow Library and Archives, UCalgary: ND-8-296
History of format
William Henry Fox Talbot patented the first negative-positive process in 1841, a paper negative called the calotype. The ability to create unlimited copies of a photographic image with light-sensitive paper was ground-breaking. However, the resulting prints lacked detail and sharpness when compared to earlier processes. The prints produced tended to be blurry, as they took on the texture of the paper. Glass plate negatives quickly replaced calotypes, as the quality of the prints produced by this improved negative-positive process was exceptional.
Machine Gun Section, 51 St. O Batt'n, Feb. 22nd. 1916. McDermid glass negatives. Glenbow Library and Archives, UCalgary: B19.
The collodion wet plate process was challenging as subject matter, processing materials and darkroom all had to be in proximity with one another. Flammable liquid collodion was first poured evenly onto a glass plate and then the plate was dipped into a silver nitrate bath. The plate was then placed into the camera, the picture was taken and then quickly processed in the darkroom before the emulsion dried.
The silver gelatin dry plates, which were coated with a gelatin emulsion of silver bromide, could be prepared and stored until the photographer was ready to take a picture. Once the exposure was complete, processing could be done when the photographer was able. Dry plate negatives were used from 1870s all the way through to the 1920s.
How the format was used
Glass plate negatives opened the world of photography to amateur photographers and other hobbyists because of the lower cost and simplicity of producing multiple copies from an original negative. Manufacturers mass produced the silver gelatin dry glass plates and photographic paper, enabling professional photographers to expand their businesses and focus on the art of photography.
Glass plate negatives tend to be more fragile than other historical processes and are prone to several types of deterioration; mechanical (broken or cracked glass, flaking or easily scratched emulsions), chemical (improper processing or the degradation of the emulsion layer) and environmental (glass corrosion from high humidity levels or water damage). Acids in the paper envelope that once held this glass plate negative (below) tarnished the negative’s emulsion, creating a reflective sheen in the darker areas of the image. The seam of the envelope can be seen down the centre of the photograph as the area under the overlapping paper seam reacted differently than the rest of the image.