Cyanotype is one of the oldest photographic processes. Ferric ammonium citrate and potassium ferricyanide, mixed in low light, coated onto paper or fabric, exposed to UV, washed in water. The result is Prussian blue — deep, cool, slightly unpredictable.
Coating
The paper is coated by hand with a foam brush. This introduces variation — slight ridges, uneven edges, areas where the solution pools slightly before being spread. These become part of the image.
Exposure
I print outside when the light allows. London in winter means slow exposures, flat light, sometimes half an hour to get the shadows to hold. In summer the same image might print in four minutes.
The variables
Temperature, humidity, the age of the sensitiser, how long the paper sat before exposure — all of these shift the outcome. No two prints from a hand-coated edition are identical. The edition number records that these prints came from the same negative and the same process, not that they are the same object.
Washing
The print is washed in cold water for several minutes. The unexposed areas dissolve away. The image appears slowly, coming up from white to pale blue to deep Prussian as the chemistry clears.
This is the moment I still stop to watch.