Collodion
Collodion is a flammable, syrupy solution of nitrocellulose in ether and alcohol. There are two basic types: flexible and non-flexible. The flexible type is often used as a surgical dressing or to hold dressings in place. When painted on the skin, collodion dries to form a flexible nitrocellulose film. While it is initially colorless, it discolors over time. Non-flexible collodion is often used in theatrical make-up. Collodion was also the basis of most wet-plate photography until it was superseded by modern gelatin emulsions. History. In 1846 Louis-Nicolas Ménard and Florès Domonte discovered that cellulose  nitrate could be dissolved in ether. They devised a mixture of ether (ethoxyethane) as the solvent and ethanol as a diluent that rendered cellulose nitrate into a clear gelatinous liquid. Collodion was first used medically as a dressing in 1847 by the Boston physician John Parker Maynard. The solution was dubbed "collodion" (from the Greek κολλώδης ("kollodis"), gluey) by Dr. A.A. Gould of Boston, Massachusetts. Wet-plate collodion photography. In 1851, Frederick Scott Archer, an Englishman, discovered that collodion could be used as an alternative to egg white (albumen) on glass photographic plates. Collodion reduced the exposure time necessary for  making an image. This method became known as the 'wet-plate collodion' or 'wet collodion' method. Collodion was relatively grainless and colorless, and allowed for one of the first high-quality duplication processes, also known as negatives. This process also produced two types of positives: the ambrotype and the tintype (also known as ferrotype). The process required great skill and included the following steps: All of this was done in a matter of minutes, and some of the steps in (red) safelight conditions, which meant that the photographer had to carry the chemicals and a portable darkroom with him wherever  he went. After these steps the plate needed rinsing in fresh water. Finally, the plate was dried and varnished using a varnish made from sandarac, alcohol and lavender oil. Dark tents to be used outdoors consisted of a small tent that was tied around the photographer's waist. Otherwise a wheelbarrow or a horse and covered wagon were used. Dry collodion plates. Richard Hill Norris, a doctor of medicine and professor of physiology at Queen's College, Birmingham (a predecessor college of Birmingham University), is generally credited with the first development of dry collodion plate when in 1856 he took  out a new patent for a dry plate used in photography in which the emulsion was coated with gelatine or gum arabic to preserve its sensitivity. Another method, using tannin, invented by Major C. Russell in 1861, followed and in 1864 W.E. Bolton and E.J. Sayce mixed silver bromide with collodion, so that by the mid-1860s the wet-plate process was being replaced.