The collodion wet plate process, also known as the wet plate collodion process, was a popular form of photography during the mid-19th century. Frederick Scott Archer invented it in the early 1850s, and it quickly became the dominant form of photography until the late 1870s when dry plates were introduced.
The process involved coating a glass or metal plate with a thin layer of collodion, a syrupy solution made from nitrocellulose and ether. The plate was then placed in a silver nitrate bath, making it light-sensitive. The coated plate was loaded into the camera and exposed while still wet.
After exposure, the plate had to be developed immediately before the collodion dried. This time-sensitive process required photographers to carry all of their equipment with them, including a portable darkroom.
The resulting images had a unique, soft-focus look due to the imperfections in the collodion and the rough surface of the glass or metal plate. The process was also prone to other imperfections, such as lens flares and light leaks.
Despite these limitations, the collodion wet plate process produced some of the most iconic images of the 19th century. Photographers like Mathew Brady and Alexander Gardner used the process to document the American Civil War, and portrait photographers like Julia Margaret Cameron used it to create beautiful, artistic portraits.
The collodion wet plate process eventually fell out of use with the development of dry plate photography and film. Today, it is mostly used by historical reenactors and fine art photographers who appreciate the unique look and process of this old form of photography.