What is wet plate collodion photography?


 * Collodion is a syrupy solution of pyroxylin in ether or alcohol and was first used to keep surgical dressings in place.
 * In 1851, Frederick Scott Archer and Gustave Le Gray simultaneously discovered collodion could be used for photography.
 * When used for photography, the collodion is spread on glass or tin plates, dipped in silver nitrate and exposed to ultraviolet light to develop an image.
 * When used on clear glass it produces a negative image, known as ambrotype, and that negative can be used to make multiple prints.
 * When a black backing is added it makes a positive, one-off image that cannot be replicated.
 * Collodion on tin is often called tintype or ferrotype.

Source:http://www.abc.net.au/news/2018-01-09/collodion-photography-method-revival-in-hobart/9311632