Cyanotypes – also known as sunprints –  are created using a photographic process developed by Sir John Herschel in 1842.

Two chemicals – potassium ferricyanide and ferric ammonium citrate – are mixed to create a light-sensitive solution.  This solution is applied to paper in a dark room.  A negative is then placed in contact with the dried coated paper, which is then exposed to sunlight or a UV lamp.  After exposure, unreacted solution is rinsed off with water.  The result is a vivid, prussian-blue cyanotype print.

Since this is a contact printing process, the cyanotype is the same size as the negative.