What is Cyanotype?
[[File:Anna Atkins algae cyanotype.jpg|thumb|Cyanotypie, Dictyota dichotoma, by Anna Atkins]] [[File:John Frederick William Herschel - Lady with a harp 1842.jpg|thumb|Sir John F.W. Herschel: ''Lady with a harp'', 1842]] [[File:Cyanotype photogram on linen by Kate Cordsen. 2016 at Florence Griswold Museum.jpg|thumb|315x315px|Cyanotype photogram on linen by Kate Cordsen. 2016 at Florence Griswold Museum]] '''Cyanotype''' is a [[photography|photographic]] printing process, which produces prints that are blue. [[John Herschel]] discovered the process in 1842. [[Engineer]]s used the process well into the 20th century as a simple and low-cost process to produce copies of drawings, referred to as [[blueprint]]s. The process uses two chemicals: [[Ammonium ferric citrate|ammonium iron(III) citrate]] and [[potassium ferricyanide]]. [[Category:Photography]]