I have been experimenting with historical printing processes.
Cyanotype was the first non-silver process discovered in 1842, three years after photography was “discovered”
Cyanotype is another UV-sensitive contact printing process. The negative is the same size as the final print. Water colour Paper is coated in the sensitizer – a mix of 2 chemicals ferric ammonium citrate and potassium ferricyanide under a safe light, and dried. The negative and paper are clamped together or placed in a contact frame and exposed in sunlight (which can take as much as 20 minutes) or under UV light. The print is then developed in running water.