Cyanotype Process


The Cyanotype is a printing process that allows for tonal variations of a cyan blue colour due to the chemical process. This was invented by John Frederick William Herschel who was an astronomer and scientist. Cyanotype is the Greek meaning of ‘Dark Blue’ and it’s main principle is a photochemical reduction of Iron (III) salts that reacts with Potassium Ferricyanide forming the blue reaction.

For the purpose of this study the following question(s) were addressed:

  1. Would I be best buying a kit or individual solutions for this process?
  2. Am I going to have enough daylight for development or will I need an alternative light source, i.e. UV lamp?


I predict that exposure times will vary rather significantly dependent on the weather conditions and amount of day light. I believe that the process will need to be completed on a very sunny day with little or under a bright lamp. I imagine results will also vary depending on the amount on contrast in the inverted digital negative, the more contrast the better the outcome.



Historic Photographic Processes Book (Library Resources)

The Cyanotype process was invented by Sir John Herschel in, in 1842 and was the first permanent photographic process. Herschel also discovered ferric salts which reduced upon exposure to light, forming (ferric ammonium), which could then be used to combine other salts, thus allowing the cyanotype process. The cyanotype and kallitype was referred to as ‘Iron Printing’ due to this unique salt combination process.

Anna Atkins, the first female photographer, made a book in the study of British algae and botanical which included her cyanotype processes as representations.

The blue colour is the result of Ferric Ammonium Citrate and Potassium Ferro-cyanine to form Ferric Ferro-cyanide.

A small amount of ferrous salts that’s created by the reducing of the light, further reacts with an apposing amount of Prussian blue to create ferrous ferro-cyanide, which is a white insoluble substance. Once washed and dried thoroughly. After washing and thoroughly drying the print a gradual oxidisation with air occurs to form ferric ferro-cyanide which is Prussian blue. This provides explanation for darkening of cyanotypes after it is subjected to air for a considerable amount of time.

A cyanotype gives the impression of durability but cab be quite fragile. Alkaline substances can degrade or erode the image. Further light exposure can also fade the Image. A unique ability of cyanotypes, un-paralleled, in photography is if faded, the cyanotype can be ‘rested’ in darkness to allow air to ‘re-oxidise’ the Prussian blue colour. Usually created with negatives and the density of the negative is related to the paper used and its ability to hold the chemicals.

Printing is achieved with exposure to the sun or UV light. Exposure times vary from 3-30 minutes depending on the density of the negative and the brightness of the light source.

Processing is achieved by simply washing the print to remove any remaining yellow colour, which is ferri-cyanide (Prussian blue). [2]

British astronomer and scientist Sir John Herschel is credited with discovering blue printing, or heliography with iron salts, in 1842. Anna Atkins is also famous for her cyanotype nature prints of natural beauty consisting of objects from the landscape.

Atkin’s is a botanist and the first female photographer. She was taught the cyanotype process by Herschel and realised it’s photographic potential, later creating her own book, Cyanotypes of British and Foreign Flowering Plants and Ferns using the process and being known as the first book as photographic illustrations. Her later books included the Sun Gardens: Victorian Photograms. (1)


Anna Atkin’s:


Gail Erwin is another artist that specialises in the historical photographic technique of creating the Cyanotype, combined with also creating Van Dyke Brown Prints, painting, print making and hand paper making with the use of mixed media.

Her aim with the Vietnam Cyanotypes was to capture the contrast of the of the country, as the 19th century cyanotype seemed the correct medium.



Process Description:

  • Cover selected paper with Iron (III) salt and Potassium Ferricyanide under a dim light due to sensitivity.
  • The resulting yellow/greenish layer of sensitised material is dried off in the dark.
  • The dried material is then exposed under a negative (or other opaque material) under a strong light (Sunlight or UV light), in a printing frame for good contact between the negative and the material.
  • Determine light exposure time over a series of contact prints.
  • Transfer material into a water bath to complete the process with a result of Prussian Blue in the areas exposed to light and to dissolve any remaining mixture of sensitising compounds.
  • Full development of blue print can be aided by adding a small amount of Hydrogen Peroxide Solution to the bath.
  • Leave to fully dry and oxidise by exposure to air.



To carry out my own research and experiment with the technique I obtained the following materials from the following internet resources:

  1. Cyanotype Kit purchased from: Sliver print £30.00 [Online] Accessed:
  2. x2 Ilford HP5 35mm black and white film, ISO 400  £9.95 [Online]                          Accessed:
  3. x1 Ilford HP5 120mm black and white film, ISO 400 £5.22 [Online]                            Accessed:
  4. Bockingfords Water Colour Paper £7.99
  5. A4 Acetate £5.99


I followed the kit instructions for mixing and preparing the papers. For the exposure time I decided to experiment a little with the exposure times to accommodate for the variable weather conditions. My first cyanotype (Fig. 1) was exposed to the sun for ten minutes which appeared to develop well.

However, when I washed the print in tap water the image began to disappear and was hardly visible. I believe that this was the result of over exposure, requiring less exposure time for further experiments.

As I continued to experiment with my exposure time, I found that five minutes in the bright sun was adequate enough for exposing the print. During the was the blue image began to remain permanently, appearing very strong and contrasted. This appeared to be the case after each print that I did continuing with five minute exposures times, with on and off cloud at times, seemed to work well.

I have also experimented with tea toning my cyanotypes, I used my weakest image to experiment with for my first attempt. I found this effective in changing the paper colour, however it also made the blue stain go very dark and it faded further, possibly due to the wash stage. Although Fig. 7 has created a water colour painting aesthetic which I am growing fond of as it gives an impressionist feel reminiscent of a Turner or Constable painting.



I found this process to be fairly simple and straight forward, however, I did have some difficulty in experimentation with exposure times. However, on evaluation it is evident that each image got stronger in definition after each print. I thought that this process would be much more complicated than it turned out to be, surprising myself in my own ability to carry out experiments accurately and effectively. I have found it to be a very effective method for capturing detail and although restricted to the single colour of blue, it has very unique aesthetic and texture that can be utilised for certain styles and media’s. I have also found the addition of tea toning for an antique effect can also provide merit in a more classic scenario.











[1] BLACKLAW, L. (2007). New Dimensions in Photo Processes: A Step by Step Manual for Alternative Techniques. Oxford: Focal Press. (Part III, Chapter 7).

[2] FARBER, R. (1998). Historic Photographic Processes. 1st Ed. New York: Allworth Press. Chapter 5: pages 59-69                                                                                                                                                        ISBN No 1-880559-93-5

[3] GAIL ERWIN, (2016). Gail Erwin Photography. [Online] Available from:                                                   [Accessed: 08 May 2016]

[4] THE GETTY CONSERVATION. (2013) Cyanotype: The Atlas of Analytical signatures of photographic Processes. [Online] Available from: [Accessed: 15th January 2016]

[5] GETTY MUSEUM, (2016). Anna Atkins. [Online] Available from: [Accessed: 08 May 2016]


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