Cyanotype - The Origins of Photography
The Cyanotype process was developed by the scientist and astronomer Sir John Herschel in 1842. He employed it to reproduce notes and diagrams (the technology would be widely used in architecture and engineering until the mid-20th century, hence the term “blueprint”).
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The process involves coating paper with a solution of iron salts (which are sensitive to UV light). Once the paper has dried in a dark room, objects (In my case mainly flowers, leaves, feathers or seaweed, either collected from my garden or found on walks) are laid on the paper, which is then exposed to light.
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After the timed exposure, the paper is washed in water to ‘set’ the image. The paper exposed to light turns blue. Where the object lay, and so not exposed to light, ensures the paper remains white.
A Cyanotype image of Cow Parsley from my garden
Additional processes can be applied to the paper before exposure. For example “Wet Cyanotype” involves re-wetting the paper with water or vinegar and sprinkling the paper with other materials, for example salt or turmeric – this increases the range of colours seen in the final image.
A Wet Cyanotype image of a Dandelion. This image included re-wetting with diluted vinegar and sprinkling with turmeric before creating the exposure.