Cyanotype

Cyanotype produces a cyan-blue print by the process of an old monochrome photographic printing. The two chemicals used in the process of cyanotype are Ammonium iron(III) citrate and Potassium ferricyanide. These chemicals when mixed in water form a resultant of a photo-sensitive solution. This resultant is applied on a material like paper. When this is exposed with a negative to the ultraviolet light, a positive image is produced.

The ultraviolet ray reduces the ferric stage to a ferrous stage. The ferrous complex is then reacted with ferricyanide. The resultant is a viscous blue dye which is known as Prussian blue. The resulting solution consequently help in the cyanotype.

The development of the picture takes place by flushing it with flowing water. The water-soluble ferrous salts are washed away, while the insoluble Prussian blue remains in the paper. This contributes the picture its typical blue color. The simple and low-cost process of cyanotype enable the engineers to produce large-scale copies of their map drawings, referred to as blueprints.

To get the proper cyanotype the proper mixture of ingredients required to make the sensitizers chemical include:

10 grams of Potassium Ferricyanide K3[Fe(CN)6]

30 grams of Ammonium Iron(III) Oxalate (NH4)3[Fe(C2O4)3].3H2O

0.5 cubic centimeter of Ammonium Dichromate (NH4)2Cr2O7 (25% solution)

100 cubic centimeter of Distilled water

There have been some confusions with the discoverer of cyanotype. The British scientist Anna Atkins is credited for bringing the process of cyanotype into the genre of photography. Sir John Herschel, the English scientist and astronomer discovered the procedure of making the sensitizers chemical. Some hold the view that Herschel was the person to invent the cyanotype process.