Collodiumlagen

Collodiumlagen, also known as collodion emulsion, is a photographic process that uses a solution of nitrocellulose dissolved in ether and alcohol to create a sticky film onto which light-sensitive silver halide crystals are suspended. This wet collodion process, invented by Frederick Scott Archer in 1851, was a significant improvement over earlier methods like the daguerreotype and calotype. The collodion itself acts as a binder, holding the silver salts to the glass plate or film. Before exposure, the collodion plate must be kept wet, hence the "wet plate" designation. The plate is then sensitized in a silver nitrate bath immediately before being placed in the camera. After exposure, it must be developed and fixed while still wet. The resulting image is sharp and detailed, with a wide tonal range. Common variations of the collodion process include the ambrotype, which produces a positive image on glass, and the tintype or ferrotype, which creates an image on a dark metal plate. The collodion process was widely used throughout the mid to late 19th century before being largely superseded by dry plate photography and later, roll film.