he cyanotype was discovered in 1842 by the English astronomer, John Herschel. This photographic printing process produces shades ranging from cyan to Prussian blue.
It is to William Herschel, his father that we owe the discovery of the planet Uranus, the cyan planet.
The paper is coated with a mixture of two products, potassium ferricyanide, and ammonium citrate. These products are not toxic.
This emulsion is applied with a brush away from daylight.
Once dried in the dark, the sheet coated with photosensitive product is brought into contact with a silver or digital negative, as it is a contact print, the image obtained will have the same size as the negative.
Then we place the press frame in the insulator for a few minutes, or under the sunlight.
After exposure to ultraviolet rays, the sheet is immersed in water,
uv exposed parts turn blue
and those that have been masked dissolve.