Bromoil is a printing process that turns a silver bromide print into an image made of oily ink. The print is bleached and hardened in a chemical bath. The gelatin then holds water in some areas and less in others. When the photographer applies greasy ink with a brush, the ink sticks most to the darker areas.
The process was proposed by E. J. Wall in 1907, and C. Welborne Piper worked out the practical method the same year. Its soft, painterly look made it popular with Pictorialist photographers in the first half of the 20th century. See also alternative processes.
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