Potassium Ferricyanide for Cyanotype
Potassium ferricyanide is one of the key components of the cyanotype process, one of the most well-known historical techniques within alternative photography.
When dissolved in water, it produces what is known as solution B, which is then mixed with solution A —prepared with ferric ammonium citrate— to create the photosensitive emulsion.
This mixture is responsible for the chemical reaction that, after exposure to sunlight or ultraviolet light, produces the characteristic blue image of cyanotype.
Preparing Solution B
A common working formula is:
Solution A
25 g ferric ammonium citrate diluted in 100 ml distilled water
Solution B
15 g potassium ferricyanide diluted in 100 ml distilled water
The final emulsion is obtained by mixing equal parts of both solutions just before application.
Application of the Emulsion
Once prepared, the emulsion can be applied to different surfaces using a brush, sponge or roller.
Common surfaces include:
After application, the surface should dry in a dark place before exposure.
Development and Blue Appearance
After exposure, the image is developed simply by washing with water.
During this process, the characteristic blue image appears and intensifies as it oxidises.
Related Products
This product corresponds to component B of the cyanotype process.
To prepare the full emulsion you will also need:
You can find more products, kits and chemicals for alternative photographic processes in our cyanotype and solar chemistry section.
