What is a cyanotype?
The cyanotype process is based on iron rather than silver and was developed in 1842 by the English astronomer and natural scientist Sir John Herschel.
Paper or fabric treated with a solution of potassium ferricyanide(III) and ammonium iron(III) citrate reacts photosensitively to sunlight and forms the dye Berlin blue (also Prussian blue, Parisian blue).
dye Berlin blue (also called Prussian blue, Parisian blue and iron cyan blue).
Found objects from nature are placed directly on the photographic paper and exposed to sunlight.
The result is a photogram: structures are emphasised and reduced to the essential.
How to store?
As with all photographic prints, the images should not be exposed to direct sunlight, otherwise they may fade.
A cyanotype will regain its original contrast if stored in a dark place for a few days.
Important: Cyanotypes need air to breathe and should therefore not come into direct contact with the glass of the frame (at least 1 mm distance).