At London’s Great Exposition in 1851, also known as The Crystal Palace Exposition, a new process, the wet collodion process was showcased.
Collodion, invented in 1846 by C. F. Schonbein, is a transparent, sticky substance created by dissolving nitrocellulose in ethyl alcohol and ethyl ether. This substance dries into a tough, transparent skin that was used as a surgical dressing.
In 1851 Fredrick Scott Archer began using collodion on glass plates in photography as an alternative for egg whites (albumen).
The wet collodion process produced sharp images with exposure times as short as five seconds, an innovation which made photography more practical for mass consumption. The one downside to this process…it had to be completed immediately. The plate had to be made, exposed and developed before anything could dry out.
Photographers today may complain about the amount of gear they have to carry around but photographers using the wet collodion process had to carry around their camera gear and a complete darkroom in order to create their images.
Here’s how they did it:
- A mixture of collodion and potassium iodide is used to evenly coat a glass plate (Ambrotype) or a black enameled iron plate (tintype or ferrotype).
- The plate is sensitized by being dipped into a bath of silver nitrate.
- Next, it is exposed while still damp and then developed using a ferrous sulfate based developer, fixed using potassium cyanide or sodium thiosulfate, washed and finally dried.
All of this had to be completed before the emulsion was able to dry.
The wet collodion process creates a negative image. When glass was used the back of the glass was covered with black paper, felt or simply black varnish. This made the image appear as a positive. This image, the Ambrotype, was often covered with another piece of glass for protection and then put into a metal case.
The cheaper tintype also created a negative image but because the plate itself had a dark enameled coating it appears to be positive. These positives could be produced more quickly, placed in a paper frame and sold.
Ambrotypes were common from 1852 to 1890 but the cheaper Tintype was in use from 1855 to 1930.