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 Collodion was also the basis of most wet-plate photography until it was superseded by modern gelatin emulsions. 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. Collodion process 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: Clean the glass plate (extremely well) In the light, pour "salted" (iodide, bromide) collodion onto the glass plate, tilting it so it reaches each corner. The excess is poured back into the bottle. Take the plate into a darkroom or orange tent (the plate is sensitive only to blue light) and immerse the plate in a silver nitrate sensitising bath (for 3–5 minutes) Lift the plate out of the bath, drain and wipe the back, load it into a plate holder and protect from light with a dark slide.