Definitions

collodion

collodion

[kuh-loh-dee-uhn]
collodion, solution of pyroxylin in a mixture of alcohol and ether. Upon exposure to air, the solvents evaporate, leaving a thin, colorless, elastic film on any surface upon which the collodion has been spread. Collodion is the forerunner of the lacquer paints that are now widely used in the automobile industry.

Collodion is a solution of nitrocellulose in ether or acetone, sometimes with the addition of alcohols. Its generic name is pyroxylin solution. It is highly flammable. As the solvent evaporates, it dries to a celluloid-like film. It was discovered about 1846 by the French chemist and writer Louis Ménard.

Wet plate collodion photography

In 1851, the Englishman Frederick Scott Archer discovered that collodion could be used as an alternative to albumen on glass plates. This also reduced the exposure time when making the image. This became known as the wet plate Collodion or wet collodion method. Collodion was also grainless and colorless, and allowed for one of the first high quality duplication processes, also known as negatives. This process also produced positives, the Ambrotype and the Ferrotype (aka Tintypes).

The process was very involved and included the following steps:

All of this was done in a matter of minutes, which meant that the photographer had to carry the chemicals with him wherever he went.

Richard Norris, a doctor of medicine and professor of physiology at Queen's College, Birmingham, is generally credited with the first development of dry collodion plate in the 1860s. In 1894 he took out a new patent for dry plate used in photography.

Medical

Other Uses

  • Collodion is widely used to glue electrodes to the head for electroencephalography.
  • Collodion is used in theatrical makeup for various effects, such as simulating old-age wrinkles 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.
  • Celloidin 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 collodio-albumen dry plate processes which he would later adapt to his microfilm techniques.

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