The cyanotype process was invented by the English polymath Sir John Henry Herschel in 1842. Herschel was an astronomer, chemist, mathematician, and natural philosopher, who was particularly interested in the scientific applications of the emerging medium of photography. As well as inventing the cyanotype, he also discovered the use of sodium thiosulfate as a permanent photographic fixer, which both Daguerre and Fox Talbot adopted in place of previous, less reliable methods of fixing. Herschel was a close friend of Anna Atkins, one of the first woman photographers and a pioneer of the cyanotype process. Like many early photographers, Atkins was also interested in science - in her case botany - and used the cyanotype process to make a remarkable series of photograms of British seaweeds and algae.
The process produces striking prussian blue images which can be toned in various colours, but despite its simplicity and low cost, it has never been as widely used as processes with a broader tonal range such as the salt print. However, it remained in use well into the twentieth century as a means of reproduction: architectural blueprints, for example, were made with cyanotype chemistry. In more recent times, the cyanotype has been rediscovered by contemporary artists and explored in relation to its historical context as well as the expressive possibilities it offers.