First tries with solarisation
The cyanotype process — from the Greek cyan, or “dark-blue impression” — was invented around 1842 by the British astronomer and chemist John Frederick Herschel (1792–1871). The benefits of the format were evident from the start.
Making a cyanotype involves placing a negative image — which could be a photographic negative, or an object, as in a photogram — on treated paper or fabric. After an iron-based solution is brushed on, the paper is placed under ultraviolet light, or here of course in the direct sun, to develop.