What is Cyanotype? 

Cyanotype is an alternative photographic process that produces a Prussian-blue print. It was invented by John Herschel in 1842. The process involves using a photosensitive solution, when exposed to ultraviolet light, undergo a chemical reaction and produce a blue pigment. They are often known as sun prints or blue prints. 

How to Make Cyanotype / Sun Print? 

To create a cyanotype, a same amount solution of ammonium citrate and potassium ferricyanide is mixed together and applied to a surface such as paper or fabric. The treated media is then dried and stored in the dark to prevent premature exposure. Before exposure, place any photo negative or any objects on the surface and place a clear sheet glass or plexiglass on top and expose in the sun. After exposure, remove all the objects and wash the paper or fabric in water. The areas that were exposed to UV light become a deep blue, while the covered areas remain white. 

In my current art practice, I use pressed flowers or plants that I collect from my neighborhoods to make botanical cyanotype prints.