Collodion

Alfred Stieglitz by Frank S. Herrmann

1860 Anonyme Un vétéran et sa femme Ambrotype

Alice Liddell as Pomona by Julia Margaret Cameron

Rev David Leavitt

Collodion is a flammable, syrupy solution of nitrocellulose (also known as cellulose nitrate, flash paper, gun cotton, and guncotton) in ether and alcohol. There are two basic types of collodion: flexible and non-flexible. The flexible type is often used in medical applications, while the non-flexible type is used in photography, particularly in the early process of making photographic plates.

History

Collodion was invented in 1846 by the English chemist Frederick Scott Archer. Archer discovered that collodion could be used as an alternative to egg white (albumen) on photographic plates, leading to the collodion process, which significantly reduced exposure times in photography. This discovery was a major advancement in the field of photography during the 19th century.

Uses

Photography

In photography, collodion is used in the wet plate collodion process. This involves coating a glass plate with collodion, sensitizing it in a bath of silver nitrate, and exposing it while still wet. The process must be completed quickly before the collodion dries, hence the term "wet plate." The result is a highly detailed negative image that can be used to produce photographic prints. This process was widely used until the late 19th century when it was gradually replaced by dry plate photography and eventually by modern film.

Medicine

In medicine, collodion is used in its flexible form as a topical medication. It is applied to the skin to hold dressings in place, to protect wounds, and to treat certain skin conditions such as warts, eczema, and ulcers. When applied, collodion dries to form a flexible, protective film over the area.

Composition and Safety

Collodion is composed of nitrocellulose dissolved in a mixture of ether and alcohol. Due to its ether content, it is highly flammable and must be handled with care, especially in environments where sparks or open flames are present. Safety measures include storing collodion in a cool, well-ventilated area away from sources of ignition.

Current Status

While the use of collodion in photography has largely been replaced by more modern techniques, it still enjoys popularity among enthusiasts of historical photographic processes. In medicine, collodion remains a useful tool for its protective and adhesive properties.