Cyanotype – A Brief Description

Cyanotype creates beautiful images using iron salts and sunlight. They are known for their bright blue color which can range from light blue to deep cobalt. It can be used to make both photographic prints and original art works. We use cyanotype mostly on paper but it can also be made on on glass, plastic, stone and cloth.

Who Invented it?

The process was invented by John Hershel in 1842 and was one of the first imaging processes. Herschel was an extraordinary man who made discoveries in astronomy, botany, and photography. His father, William Herschel discovered the planet Uranus and John extended this work with the discovery of many of the planets moons. John was trying to find a way to make copies of his astronomy notes when he discovered that iron salts could be treated to become light sensitive. When exposed to sunlight, or any UV light source, the salts formed a permanent iron dye with intense blue color. The resulting dye, known as Prussian Blue, has a color running from light blue to cobalt to almost black. He used his notes as a negative to print paper treated with the chemicals and the “blue print” was born!

How is A Cyanotype Made?

Cyanotypes are produced through a contact printing process where the image is formed by selectively blocking sunlight.

A full sized negative is used to produce the image – the negative can anything from physical objects to photographic film
Paper is coated with a solution of iron salts in a room with very dim light and allowed to dry
The sensitized paper is placed in contact with the negative and clamped in a printing frame
The frame is placed in sunlight for 10 to 60 minutes to produce an image
The paper is washed in water (in a darkened room) to remove unreacted iron salts, leaving behind an image
The print can also be toned with various substances (like coffee or tea) to produce different colors