My Cyanotype Process Explained
24 October 2020
I thought it’s about time I talked a bit about the cyanotype process – it’s a photographic printing technique that does not use a camera and was introduced in 1842 by John Herschel. A year later Anna Atkins created a series of books using the cyanotype process to document plants.
The cyanotype image is made by applying ultraviolet sensitive chemicals to paper. This is exposed to sunlight to develop and then washed in running water to fix the image.
There are various formulas for creating the cyanotype solution but they all involve mixing various quantities of two chemicals: ammonium citrate and potassium ferricyanide. These are in powder form and prepared by combining with distilled water and storing away from light. I use a formula at the moment from my go to reference book which is called Cyanotype. The Blueprint in Contemporary Practice by Christina Z. Anderson
I apply the combined chemicals to alkaline free watercolour paper – I had been using Fabriano Artistico 300 gsm watercolour paper until recently but I have just changed to Arches 300 gsm watercolour paper as the coating on the former had changed. I always use hot pressed paper as I like a very smooth surface but a lot of people use a textured surface – just depends on your personal preference. Once coated the paper has to dry in a darkened room before it is ready to use.
To create the imagery I use a combination of digitally prepared and printed transparencies of vintage sundial diagrams, birds and insects. I then place this transparency onto the prepared paper and add real flowers or plants.
I place this on a flat surface outside in the sun and put a piece of glass on top to hold everything firmly in place.
Anything that stops the light reaching the sensitised paper will appear white when developed and everything else will be blue.
The sun provides a convenient source of UV (ultraviolet) light and exposure times vary according to intensity and orientation of the sun, amount of cloud and ambient temperature. Exposure times can vary from 30 mins upwards. This can be calculated scientifically using a stepwedge test but you soon get a good idea of timings comes with practise using a particular combination of chemical formula and paper.
Once it has been in the sun for the required amount of time the image is developed by holding the paper under running water for at least 6 minutes. It is a great feeling to see the image appear. It takes up to 24 hours for the paper to dry completely and only then can I add the gold metal leaf detail.
I apply the gold metal leaf detail by hand. It’s a delicate process which involves applying a water based glue which dries until tacky – approximately 10 minutes and before applying the gold metal leaf, rubbing away any excess. I then apply a clear shellac varnish to prevent the gold metal tarnishing. If I’m not careful this is a point where the whole image can be ruined which is very annoying.
I love this technique as there is a certain amount of serendipity about the process so you never quite know what to expect. Sometimes the resultant image is no good at all but that’s just how it goes!
If you want any more details about how I make the work just contact me and I’ll try and help!