A Cyanotype is a photographic printing process that results in a cyan-blue print.

The process was popular in engineering circles well into the 20th century. The simple and low-cost process enabled them to produce large-scale copies of their illustrations & written notes. For this reason a Cyanotype is commonly called a blueprint, and was often used for reproducing architectural plans and diagrams.

The process was widely used for photographic prints, recording life of the time however by nature Cyanotypes fade easily.

Two chemicals are used in the Cyanotype process: Ammonium iron(III) citrate Potassium ferricyanide.