Cyanotype is a non-silver photographic process. It works on the principle that certain iron salts are sensitive to light. When the iron salt, in this case ferric ammonium citrate, reacts with potassium ferricyanide it forms insoluble ferric ferricyanide, also known as Prussian Blue. The density of the colour can be controlled by exposure time, the type of light, and the time of year if exposure is by sunlight. Cyanotype prints are made by contact printing. A good quality paper or cloth is coated in low light with the emulsion, and air dried in the dark. A negative the same size as the final image is placed on the dried sensitized paper, sandwiched under glass and exposed to the sun (or UV light). Exposure can be judged by the colour changes – when the colour reaches blue-grey exposure is complete. To develop the print, wash in water until the unexposed areas are clear of emulsion. The colour of the print is then intensified by dipping it in a bath of dilute hydrogen peroxide for 30 seconds.
Exhibitions:
2002 Momento Mori, Australian Centre for Photography, Sydney, Australia
2002 BOULEVART 5UV Radio Adelaide Windows, Adelaide, Australia
2001 Camera Obscured, Central Art School Gallery, Adelaide, Australia