Notes on cyanotypes
A cyanotype is a cameraless photography process that originated in 1842, not long after the birth of photography. It involves coating paper (or any other material) with a mixture of two chemicals – ferric ammonium citrate and potassium ferricyanide – and exposing it to sunlight or UV light. When the paper is rinsed in water it oxidises to create beautiful Prussian blue (not exactly cyan) images.
By placing interesting objects (leaves and feathers are always a winner but any object with a distinctive shape will do, making it the perfect lockdown project – there's no need to leave the house) on the paper in the sun, the paper exposed to the light will go blue, leaving a white silhouette of the placed object.
If this sounds technical or complicated, it's not, for I accomplished it with ease. Look online for packs of cyanotype or sun sensitive paper. On a sunny day, place the paper either outside in the sun or on a sunlit windowsill inside. Put the objects on the paper for 10-30 minutes, depending how sunny the day (if using flat, light objects like leaves or feathers, it's a good idea flattening them with a piece of glass against the paper; the images will turn out sharper and they won't blur the picture by moving). Rinse the print in cold water for a minute, then leave in a shallow tray of water for five. If you're into photography and will probably never have a darkroom, watching the image magically appearing as you rinse it is probably the nearest you'll get to the darkroom experience.
It's much easier buying pre-coated paper in packs, but if game why not try buying the two chemicals and coating your own paper or other material (I've seen examples online printed on shells).
Cyanotypes were invented by Sir John Herschel. He thought they had no artistic merit, and indeed the process was used by engineers up to fairly recently to produce architectural blueprints. Photographer and botanist Anna Atkins used the process to illustrate her herbarium. Although the intention was largely scientific, the results were beautiful, and her 1843 book, Photographs of British Algae: Cyanotype Impressions, is said to be the world's first photographically illustrated book.
On Flickr A cyanoytpe I did years ago of water pistols turned out pretty cool, like an X-ray.