Cyanotype is photography related printing process in which we get monochrome images in blue tint. This process  was discovered by English scientist Sir John Herschel in 1842. Herschel used this process to reproduce diagrams and notes. It was Anna Atkins who introduced this method for photographic purposes in order to document ferns and other plant life. This process produces a cyan-blue print. Nowadays, engineers use this technique to produce blueprints of plans and other drawings. In this printing, a photosensitive solution is made by mixing potassium ferricyanide and ferric ammonium citrate. This solution is applied to paper and is exposed to ultra violet rays to obtain positive and monochromatic images in tints of blue.