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" 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; 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.
- Load the plate holder into the camera, withdraw the dark slide and expose the plate (can range from less than a second to several minutes)
- Develop the plate (using a 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 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 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.