The compound has widespread use in blueprints and in photography. Iron and copper toning involve the use of potassium ferricyanide. Potassium ferricyanide is used as a reducing agent to remove silver from negatives and positives, a process called dot etching. In color photography, potassium ferricyanide is used to reduce the size of color dots without reducing their number, as a kind of manual color correction. The compound is also used to temper iron and steel, in electroplating, dyeing wool, as a laboratory reagent, and as a mild oxidizing agent in organic chemistry.
See also: potassium ferrocyanide, Prussian blue