Collodion is a solution of nitrocellulose in ether or acetone, sometimes with the addition of alcohols. Its generic name is pyroxylin solution. It is highly flammable. As the solvent evaporates, it dries to a celluloid-like film. It was discovered about 1846 by the French chemist and writer Louis Ménard.
In 1851, the Englishman Frederick Scott Archer discovered that collodion could be used as an alternative to albumen on glass plates. This also reduced the exposure time when making the image. This became known as the wet plate Collodion or wet collodion method. Collodion was also grainless and colorless, and allowed for one of the first high quality duplication processes, also known as negatives. This process also produced positives, the Ambrotype and the Ferrotype (aka Tintypes).
The process was very involved and included the following steps:
All of this was done in a matter of minutes, which meant that the photographer had to carry the chemicals with him wherever he went.
Richard Norris, a doctor of medicine and professor of physiology at Queen's College, Birmingham, is generally credited with the first development of dry collodion plate in the 1860s. In 1894 he took out a new patent for dry plate used in photography.