Ambrotypes were used c. 1851 – 1865. It was a successor to the daguerreotype and was also a direct positive image on glass.
Ambrotype of an unidentified couple (back). Glenbow Library and Archives, UCalgary: PA-2395. Anita Dammer photo.
Ambrotype of an unidentified couple (front). Glenbow Library and Archives, UCalgary: PA-2395. Anita Dammer photo.
Ambrotype of an unidentified man (back). Glenbow Library and Archives, UCalgary: PA-678-5. Anita Dammer photo.
A clean glass plate was coated in a thin layer of collodion, then dipped in silver nitrate. This plate was then exposed in the camera while the plate was still wet. The photographer manually controlled exposure time and lighting. Then the photographer developed the photograph in a developing solution and let it dry. This wet plate image was grayish white and could be viewed as a positive just by backing it with dark material or painting the back with black varnish. Before painting with black varnish, the image could be hand coloured. Another plate of glass was added to the emulsion side for protection and was originally sealed to the first plate with balsam resin. Once sealed, the ambrotype was mounted to a frame and put in a protective case, much like daguerreotypes.
History of the format
The ambrotype was introduced in the 1850s as a successor to the daguerreotype. It was patented in 1854 by James Ambrose Cutting, from Boston, Mass. The image quality was inferior to the daguerreotype. However, it was cheaper and easier to produce. The ambrotype is also known as a collodion positive. In the 1860s, the tintype, a newer photographic process, replaced the ambrotype.
Burgess, N. G. (1856). The Ambrotype Manual: A Practical Treatise on the Art of Taking Positive Photographs on Glass, Commonly Known as Ambrotypes. 2nd ed. New York: D. Burgess. Retrieved from https://link-gale-com.ezproxy.lib.ucalgary.ca/apps/doc/ALFWEB658071478/NCCO?u=ucalgary&sid=NCCO&xid=00c2691f
How people used the format
Since the ambrotype used the wet collodion process, it was best suited to photo studio work. Photographers with a travelling darkroom could, however, create ambrotypes in other locations. Ambrotypes could not be used to make acceptable reproductions due to their limited density range. Therefore, each ambrotype is original and unique.