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Craig Keenan: A blog on Cyanotypes

Posted on July 5, 2017

Craig Keenan: A blog on Cyanotypes

Cyanotypes; A brief history of discovery, process and application.

(si ane, tip noun Etymology: cyan- + -type : blueprint)

[Craig Keenan // @craigiskeenan]



In 1842 mathematicianastronomerchemist, and experimental photographer Sir John Herschel discovered the process of cyanotyping. A cost effective means of reproducing notes and diagrams. He aimed to find a new chemical process for reproducing photographic images that was more affordable than contemporary silver based processes.  A friend and colleague of his, Anna Atkins, later used the technique to produce the worlds first photographically illustrated book, Photographs of British Algae: Cyanotype Impressions. A remarkable woman who paved the way for how we engage with photography today.

The process works on the same basis as a photogram or contact print, where a UV light sensitive emulsion is prepared and then applied to a porous substrate like paper.

Once the substrate has dried, objects or a negative may be directly applied and then exposed to UV light (the sun.)

After the desired exposure time is up, the paper is then stopped and fixed simply by rinsing and resting in water. Due to the nature of the chemicals used to make the emulsion, the final result is Prussian blue or a Cyan, hence the name.

The process caught on and became the most popular way of reproducing engineering and architectural diagrams and information, before the invention of the photocopier. And has in later years become an artful practice. A means by which someone can produce beautiful reproductive and photographic results, with a relatively simple set up.




I find this process is great way to engage with digital and analogue practices, combining the best of both worlds and doing away with the farcical debate: Which is better, analogue or digital photography? I find the only limiting factor (the fact that the results are exclusively monochromatic blue) actually quite freeing as it shapes the way I choose and frame the subject I'm working on.