Wet-plate (collodion) process is a photography technique invented by Fredrick Scott Archer and Gustave Le Gray in 1851. It was to replace the first practical photographic process, the daguerreotype. The process involved a soluble iodide being added to a solution of cellulose nitrate and coating a glass plate with the mixture. The tin-type (another type of method) was meant for casual portraiture for itinerant and amusement part photographers. The wet-plate process could also be used in a dry form. However, it is mostly confined to landscape photography. This plate was exposed in the camera. This process was beneficial to photographers because it provided enhanced amounts of clarity and detail.
Interesting Facts:
Although it was widely observed by photographers in the 19th century, it had a disadvantage, which was that the entire process, from start to finish, had to be done before the plate dried.
The world's largest wet process collodion glass plate negatives are still around to this day. They are held at the State Library of New South Wales.
The wet-plate process created sharp prints and it dominated the photography world for the next thirty years.