Cyanotype process - ghollyp/uvled GitHub Wiki
Cyanotype is a photographic printing process discovered by John Herschel in 1842 as an easy and cheap way to copy his notes. The process was used to reproduce technical, engineering and architectural drawings and diagrams. The copies are called blueprints even today. Many photographers, for example Anna Atkins, used cyanotype to create photograms and large format contact prints.
The process is based on light sensitivity of ferric salts, namely Potassium ferricyanide and Ammonium ferric citrate.
The recipe
| Stock solution A | |
|---|---|
| Distilled water | 100 ml |
| Ammonium ferric citrate | 25 g |
| Stock solution B | |
|---|---|
| Distilled water | 100 ml |
| Potassium ferricyanide | 10 g |
The sensitizer solution is obtained by mixing Solution A with Solution B in 1:1 ratio. It can be applied on any receptive surface as watercolor paper or fabric and let dry in dark place. The foam brush can be used to apply thin and even coating of sensitizer on the paper.
After the exposure the picture is developed by rinsing under running water for a few minutes. Developed picture will darken after drying out after some time. The darkening can be accelerated by adding little bit of 3% hydrogen peroxide to the developing water.
Click here for more information about cyanotype in Czech language.