The traditional way of making a cyanotype print is to coat paper with a light sensitive solution. Keep the coated paper (or material) in the dark till dry. Objects or negatives can then be placed on the paper to make a print as the area that is shaded with the object, or the black of the negative, will protect the paper from exposure. After the paper is exposed to sunlight or a UV light it will change to a blue-grey colour. Length of exposure will vary, but 6 mins in daylight is a reasonable time to start with. Excess solution is then washed off in water and the work hung up to dry with plastic pegs.
To make the light sensitive solution two chemical solutions are mixed separately:
1. 25 grams Ferric ammonium citrate (green) in 100 ml of water.
2. 10 grams Potassium ferricyanide in 100 ml of water.
The two solutions are then mixed in equal parts to create the third solution, and it is this that you coat the paper with. It takes some practice to get it right – too thin a coat will not work, and too thick a coat will wash off.
It is a good idea to wear a mask when mixing the dry powder, and gloves while you are working with both powder and the solutions.