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The Cyanotype Process
Transcript of The Cyanotype Process
Sir John Herschel (1792–1871) Invented the Cyanotype Photographic Printing Process
Herschel, an Astronomer and engineer, invented the cyanotype process as a way to duplicate engineering drawings. He wanted a simple but effective process that could be done quickly and easily. He wasn't looking at photographic image quality, simply a way to duplicate drawings with manually coping them.
Anna Atkins (1799-1871)
Anna Atkins produced the first published book of photographs using the cyanotype process. The book, entitled British Algae and published in 1843 contained cyanotype photograms of Algae (seaweed) from around the coasts of Britain
Even the cover was a cyanotype image of hand written text, probably written in black Indian Ink on thin tracing paper
The process made it possible to create multiple perfect copies of a technical or engineering drawing (more commonly known as Blue Prints) quickly and simple without he aid of complex equipment.
The process eliminated the the common problem of mistakes being made by technicians re-drawing copies and the cyanotype process is stable and lasts a long time particularly when stored in the dark.
The Cyanotype Process
: 25 grams Ferric ammonium citrate (green) and 100 ml. water
The cyanotype is made up of two simple solutions:
: 10 grams Potassium ferricyanide and 100 ml. water.
Don't worry Ferricyanide is not the same as Cyanide and
Cyanotype is an ultraviolet (UV)* sensitive contact printing process that requires, as do most of the non-silver processes, a negative the same size as the final print. Of course you can use transparent, translucent, or opaque objects to make cyanotype photograms as Atkins did. The main source of UV is the Sun.
How Cyanotype Works
*UV Light is invisible to the human eye and is what causes sunburn if you spend too long in the summer sun.
The raw chemicals first need to be mixed with distilled water into two solutions, A & B.
The solutions are then mixed together to make the active light-sensitive solution C.
Solution C is light yellow in colour and is painted onto paper and allowed to dry before use. The paper must be kept away from sunlight.
You can lay a selection of 2D and 3D objects on the surface of the paper in order to create an image.
Then the paper is laid out in the sun for upto 30 mins (depending on the time of year) until the background turns a dark green/grey.
The cyanotype print is washed in water to develop the image.
A copy of an early edition of this book is in the Museum of the History of Science in Oxford
Finally the print needs to fully dried.