Cyanotype Chemistry - Potassium Ferricyanide

Cyanotype is an antique photographic printing process discovered in 1842, known for producing rich, Prussian blue monochrome prints. A UV-sensitive iron compound coats fabric or paper, and exposure to sunlight develops the image — it's the same chemistry behind the term "blueprint."

Cyanotype has a wider range of tones, but it's limited to blue, while SolarFast comes in 14 different colors. Both are sun-activated and share similar exposure techniques.

Cyanotype is non-toxic and doesn't pose a significant health risk, though you should still avoid ingesting, inhaling, or getting the chemicals on skin. It's safe for kids with adult supervision and makes a great classroom activity.

Yes, cyanotype prints are archival. That said, yellowing can occur if prints are exposed to phosphates or alkaline environments, such as certain detergents.

Since cyanotype is transparent like a dye, printing on a colored surface has an additive effect — for example, yellow fabric produces a green print, and red fabric produces a purple print, instead of the usual blue on white.