A Mini History of Cyanotypes

A little bit ago, I thought I would play around with some cyanotype chemicals that I had stashed. The chemicals were a little old, which I think caused a bit of a problem in terms of coating the paper.

I know they're not perfect, but I still liked the strange color gradations and textures.

The cyanotype process was created by Sir John Herschel in 1842 as a means to create a permanent photographic image. Herschel was a scientist and astronomer, and he developed the cyanotype process by utilizing the light sensitivity of iron salts.

A piece of paper is coated with two iron-based chemicals— ferric ammonium citrate and potassium ferricyanide— and the paper is allowed to dry in a darkroom.  When combined with an organic substance, iron salts become light sensitive, and in this case, most sensitive to UV rays (sunlight).

The iron contained in this chemical mixture reacts to sunlight, oxidizing and breaking down, releasing carbon in the form of carbonic acid. Objects are then placed directly on the paper, and then everything is placed in direct sunlight. Exposures are a bit longer at around 15 minutes or so, and after the paper and object had been exposed to sunlight, a white image will appear where the object had been in contact with the paper. The white areas occur in places that had not been exposed to sunlight.

              

Anna Atkins, 1861

After exposure, the paper is rinsed with water, which removes the unexposed iron salts in the photographic chemistry. As the print dries, oxidation occurs, deepening the tone of the cyanotype and giving it the beloved "Prussian blue" color cyanotypes are known for. This vivid blue chemical mixture is called ferric ferricyanide. (Later, a similar process was used by architects to duplicate documents—hence the term "blueprints"!)

Anna Atkins was prolific in her use of cyanotypes to catalog the plant life she studied. Atkins created several books that presented plants and other wildlife specimens at their actual size, as they could be placed directly on the paper to be exposed.

         Cystoseira fibrosa, c. 1843-1853

       from Photographs of British Algae:

           Cyanotype Impressions, Part II, 

                            Anna Atkins

Anna Atkins' images are both scientific and elegant and they were used by other scientists as sources for their work and research. She made great progress for women in the fields of science and photography, which at the time was quite difficult.

Her work in the field provided crucial insight into the untapped uses of photography, proving that it was a valuable and versatile medium.

Delessaria sinuosa, c. 1843-1853

         from Photographs of British Algae:

            Cyanotype Impressions, Part V, 

                            Anna Atkins