dry processing

Dry processing in photography refers to methods that eliminate the need for liquid processing baths, allowing for the creation of prints without traditional wet darkroom techniques.1

One approach involves incorporating development and stabilization chemicals directly into the paper's emulsion within microscopic capsules. Upon heating the exposed paper, these capsules burst, releasing the chemicals to act on the silver halide. The solvent then evaporates, resulting in a dry print. This method is useful for creating proof prints and enlarging microfilm images.1

Another dry processing technique utilizes diazo compounds. These materials are sensitive to ultraviolet light and, after exposure, can form dyes or create an image through the formation of nitrogen gas bubbles when heated. These processes are often used for duplicating microfilm.2

The development of the dry plate in the 1870s, using a gelatin emulsion of silver bromide, was a significant advancement. It allowed plates to be prepared in advance and developed later, freeing photographers from the need for portable darkrooms and paving the way for handheld cameras and snapshot photography.34