CYANOTYPE

Sir John Herschel began by experimenting with sun prints (or photograms). These were one of the earliest forms of photography and involved laying an object on chemically-treated paper before exposing it to a light source.

Later, in 1842, he used paper coated with a solution of iron salts, sun exposure and a water wash to create the very first cyanotype – a white image on a deep blue background.

This method proved to be easier, cheaper, and more durable than the previous silver-based method.

It may not look like the type of photography that we are used to, but Herschel was able to use cyanotype printing to make copies of his notes and diagrams.

Did you know? The term 'blueprint' comes from the use of cyanotypes.

How do cyanotypes work?

When ferric ammonium citrate or ferric ammonium oxalate is mixed with potassium ferricyanide, it becomes sensitive to UV light.

These chemicals can be painted onto paper or fabric and left to dry in a dark room. Once dry, objects can be arranged onto the paper and placed in the sun.

The UV rays from the sun react with the chemicals on the paper to create the recognisable cyan-blue background. Where the paper has been covered with an object it will remain white. [positive and negative space]

Once the chemicals are rinsed off with water, fixing the print so it is no longer sensitive to the sun, you are left with a beautiful print.

How to create your cyanotype

1) Pick your specimens. Collect leaves or natural material from your garden or local green space, or find objects around your home.

2) in a darkened room, prepare your material by brushing the chemical [pale green] onto your paper.  Usually, you would let this dry, but we are time poor so we do a wet method and use the paper straight away

3) Arrange your specimens. A piece of glass can be placed over your specimens for a sharper image. Use clips to hold it all firmly in place.  if materials are bulky you may need to skip the glass, but try to avoid the specimens moving! 

4) Place in the sun. It can be a clear hot summer's day or a cloudy winter's day, there will still be UV rays that will help the chemical reaction. The amount of time it needs to be left in the sun, however, may vary depending on the time of the year. 10-15 minutes on a sunny day may be all you need!  The chemical will start to change colour from a bronze [skin colour] to a dark blue].

5) Once developed enough, take your print inside and keep it out of the sunlight. You will notice that the print looks reversed.

6) It is now time to rinse your print with water. This will wash off any solution and fix the image so that it will no longer be affected by the sun.

7) Leave your print to dry. you can put it through a peroxide bath to deepen the blue, but this will naturally occur as well over time.  Once dry you will be left with your beautiful cyanotype print.

DID YOU KNOW YOU CAN USE SEE-THROUGH TRANSPARENCIES AS WELL - TRY PRINTING PHOTOGRAPHS ONTO CLEAR ACETATE AND COMBINING WITH NATURAL FORMS... YOU CAN ALSO DRAW ON TRANSPARENCIES [OR PHOTOCOPY YOUR DRAWINGS TO IT] AND COMBINE THESE WITH NATURAL FORMS.