the "wet plate" process
Developed by Frederick Scott Archer in England in 1851, the wet-plate collodion process replaced the more tedious daguerreotype process that had been popular through the 1840's. To take an image, the photographer must flow a chemical mixture over a clean glass plate creating a thin "film" that once sensitized in a bath of Silver Nitrate, becomes sensitive to light. The sensitized plate, while still wet, is carried to the camera where the subject, already posed, is ready and waiting. Dependant on light conditions, exposures may range from "instantaneous"-or as fast as the lens cap can be removed and replaced- to upwards of 20 seconds.
developing the picture
Once the image is taken, the plate must then be carried to a nearby darkroom where it is developed and fixed. When done, the finished product is a one-of-a-kind image on glass known as an ambrotype. This style of photography remained popular from 1852 to about 1880 when silver gelatin dry plates came into use.