Cyanotype

The cyanotype process was invented by Sir John Herschel in 1841. This simple process produces a continuous tone image of Prussian blue using a sensitizing solution.

It was first used to record herbarium specimens without the use of a camera. The specimens were placed directly against sheets of paper coated in the sensitising solution and exposed to light.

 The process was also used in the 1920's to reproduce technical drawings. Most commonly in engineering and architecture to create blueprints.

There are so many variable factors that effect how a cyanotype print turns out, that it can be a great challenge to reproduce the same result time after time. Variables such as the humidity, temperature, brushing the emulsion on the paper, how you wash the print, to your mood on the day. There are a multitude of intricacies one must remember and document for repeatable results. 

My process for cyanotype

The flower is photographed and a inkjet negative transparency is produced.
Cyanotype Stock A solution (25g Ammonium iron(III) citrate to 70ml water) + Stock B solution ( 10g Potassium ferricyanide to 80ml water).
Proportions of the Stock A + B are mixed together to produce a photosenstive solution that is brushed onto 300gsm watercolour paper in a darken room.
The transparency negative is placed on top of the paper and exposed to sunlight for a 30+min duration.
The watercolour paper is washed until the highlights are cleared.
It takes a further 2 to 4 weeks for the paper to be fully dried.

Botanica colour

All my alternative prints (cyanotype) start from a colour photograph.