K3[Fe(CN)6] – potassium ferricyanide – exists as bright red crystals that are soluble in water and form a yellow solution. It was initially used in the production of Prussian blue dyes. Nowadays, potassium ferricyanide is widely used in blueprints (reproductions of technical drawings) and as a color-forming component in photography. It is also used as an electrolyte in the production of electrochemical devices, and to produce fuel in pyrotechnics.