Collodioncarbon

Collodioncarbon is a photographic material that uses a collodion binder for light-sensitive silver halide crystals. It was a significant development in the mid-19th century, offering a more stable and reproducible alternative to earlier wet plate processes. The collodion, typically a solution of nitrocellulose in ether and alcohol, was coated onto a glass plate, and then sensitized with silver nitrate. This created a fast and sensitive emulsion capable of capturing sharp images.

The term "collodioncarbon" specifically refers to the use of collodion in conjunction with carbon printing. Carbon printing itself relies on the light sensitivity of dichromates. When a pigmented gelatin or albumen layer is exposed to light through a negative, the exposed areas become hardened and insoluble. Subsequent washing removes the unexposed, soluble material, leaving behind a permanent image formed by the pigment suspended in the hardened binder. In collodioncarbon processes, the collodion acted as a support or binder for the light-sensitive elements, influencing the fine detail and tonal range achievable. These processes allowed for rich, permanent prints with excellent detail.