Коллодий: Құрамы, қолданылуы және тарихы

Flammable, syrupy solution of nitrocellulose in ether and alcohol

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 Collodion was also the basis of most wet plate photography until it was superseded by modern gelatin emulsions.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.

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.

Non flexible collodion is used in theatrical makeup for various effects. When applied to the skin, it shrinks as the solvent (usually ether or alcohol) evaporates, causing wrinkles and is used to simulate old age, or scars. Collodion is used in the cleaning of optics such as telescope mirrors. The collodion is applied to the surface of the optic, usually in two or more layers. Sometimes a piece of thin cloth is applied between the layers, to hold the collodion together for easy removal. After the collodion dries and forms a solid sheet covering the optic, it is carefully peeled away, taking contamination with it. Collodion is a pure type of pyroxylin used to embed specimens which will be examined under a microscope. While in Paris, René Dagron became familiar with the collodion wet plate and collodion albumen dry plate processes which he would later adapt to his microfilm and Stanhope production techniques. Collodion was used by Alfred Nobel in his development of blasting gelatin, a more powerful, flexible, and water resistant variation of his already successful dynamite. Some types of nail polish also contain collodion.