Cyanotypes are one of the oldest photographic printing processes in photography. What makes it unique is its shade of cyan blue. The word ‘cyan’ comes from the Greek meaning dark blue substance.

The technique was invented in 1841 by the astronomer and scientist Sir John Herschel. Cyanotypes were traditionally used for reproducing the technical drawings of architects and engineers. It was the botanist Anna Atkins who used the cyanotype printing process in 1843 to create an album of algae specimens. Her book ‘Photographs of British Algae: Cyanotype Impressions’ is considered the first photographically illustrated book.

The cyanotype process uses a mixture of iron compounds, which, when exposed to UV light and washed in water, oxidise to create Prussian Blue images.