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Collodion
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Collodion an inflammable, syrupy solution of pyroxylin in ether and alcohol, used as a surgical dressing or to hold dressings in place. When painted on the skin, collodion dries to form a flexible cellulose film. While it is initially colorless, it discolors over time.
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.
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Encyclopedia
Collodion an inflammable, syrupy solution of pyroxylin in ether and alcohol, used as a surgical dressing or to hold dressings in place. When painted on the skin, collodion dries to form a flexible cellulose film. While it is initially colorless, it discolors over time.
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:
- Clean the glass plate (extremely well)
- Flow the glass plate with "salted" (iodide/bromide) Collodion
- Immerse the plate in a silver nitrate bath (for 3-5 minutes)
- Expose the plate (can range from less than a second to several minutes)
- Develop the plate (using an ferrous sulfate based developer)
- Fix the plate (with potassium cyanide or sodium thiosulfate)
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 gum sandarac, alcohol and lavender oil.
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. When applied to the skin, it shrinks as the solvent (usually ether or alcohol) evaporates, causing wrinkles.
- 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.
- Collodion was used by Alfred Nobel in his development of blasting gelatin, a more powerful, flexible, and water resistant variation on his highly successful product, Dynamite.
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