Cyanotypes I— A Short Introduction
Cyanotype is an alternative photographic process that creates images in intensive Prussian blue (“cyan” = blue). I’ve been making cyanotype prints on and off for years and in this two-part series, I will show you what I’ve learned along the way. The first part of the series is a short introduction to the basic process allowing you to emulate it at home. Wherever possible I will link to additional resources. The second part of the series will cover artistic approaches I found particularly remarkable. Let’s get to it!
First things first: the cyanotype process was invented in 1842 by Sir John F.W. Herschel (1792–1871) who used the word “cyanotype” to refer to all photographic processes that resulted in the typical Prussian blue color (also called “Berliner Blau”). Only a year later, his acquainted botanist Anna Atkins (1799–1871) created the first photo book about British plants combining cyanotype with organic photograms. A photogram is an image created without a camera by placing an object (here plants) directly onto light sensitive material. Atkins went on to produce a number of important early cyanotype publications and her style has remained extremely popular ever since.
The traditional cyanotype process is simple, cheap, safe, and very similar to the development of black and white photographs. A paper is coated with photosensitive chemicals and placed underneath a negative image or an object. Then it is exposed to UV-light, washed and dried afterwards. Newer versions of the process exist but tend to be more complicated and involve toxic chemicals. In this article, we will stick to the traditional one.
Chemicals and Coating
The photosensitive solution necessary for cyanotypes is essentially a mix of two chemicals, green ferric ammonium citrate and potassium ferricyanide. Both can be ordered online, pre-mixed solutions by different brands are also available. The chemicals can be stored in a cool and dark place (solutions in brown glass bottles), for a long time. Generally, all chemicals in this article are safe to use but still take precautions and be careful. While many variations exist, a standard formula is to dissolve 10g ammonium citrate in 40ml water (solution A) and 4g potassium ferricyanide in 40ml water (solution B), top up both solutions with water to 50ml each.
You can rest solutions A and B for 24h or mix them immediately (ratio 1:1) into the clear yellow-greenish final solution which is photosensitive. From now on, work in the dark or under red light. The coating of the paper is no rocket-science. Simply use a soft brush to apply the solution to the paper and make sure that the surface is well covered and dries properly, for instance by using a hairdryer.
Choosing the correct paper for your print requires some experience but to begin with a relatively thick watercolor paper of around 200g or more is the best way to go. Because it is later repeatedly washed, thicker paper is more durable and easier to handle. Also, cyanotype not only works well on paper but on many different surfaces, such as wood, cotton, and porcelain.
Exposure
When the paper is dry and you have an image at hand, both can be placed into a contact frame. There are different ways to get an image (a negative, digital negative or a photogram) but the basic printing process remains the same.
Aside from its particular blue color, cyanotype is typically associated with the sun because the coated paper reacts with UV-light. The logic behind this is simple: UV-light falls through the glass of the frame onto the paper where it reacts with the chemicals. All parts covered by the object will be exposed to less or no light, the chemicals will not react and later can be washed out, leaving beautiful contrasts to the parts that have been exposed.
In terms of exposure times, I found 20 min to be a good rule of thumb for strong light, e.g. sunny summer days, but of course this depends on your image and the intensity of the light source. If you cannot or do not want to depend on the sun, you might want to consider building an exposure unit — essentially a UV-light in a box. It requires some effort but for the cyanotype enthusiast it can well be worth it. Nerd fact: Use UV lamps with a high 395–405nm spectrum. Finally, please take precautions when working with UV-light as it damages your eyes and skin.
Washing and drying
A good wash is crucial to stop the print from developing. After the print has been exposed, gently wash out all residual chemicals under running water. Washing is also important because here the image will show its true colors. Literally, because the print will take its typical blue color, and figuratively because insufficiently exposed details will be washed away. For basic prints, a couple of minutes of washing will do but for more ambitious projects it can take 30 minutes or longer.
Over time, the print will naturally oxidize and give you more pronounced and dense colors. You can speed this up by bathing it in a 0,3% hydrogen peroxide solution. Afterwards, wash the paper again and let it dry thoroughly. Consider a UV-protective varnish as the final step because cyanotypes are prone to fade over time.
Voilà! You have made a cyanotype print — well done!
Last but not least, this was a basic introduction to the cyanotype process and not a fixed set of rules. Feel free to experiment in any way you want. The second part of this series will present distinct artistic approaches to demonstrate the versatility of cyanotypes.
tldr:
You need
- green ferric ammonium citrate
- potassium ferricyanide
- hydrogen peroxide solution
- paper, ca. 200g
- UV-light (sun, lamp, or UV-box)
- a brush
- an image (flat object aka photogram or digital negative)
- a contact frame
- running water and brown glass bottles
too short, want more:
- Christopher James (2016) — The Book of Alternative Photographic Processes. Free chapter on cyanotype here.
- Christina Z. Anderson (2019) — Cyanotype. The Blueprint in contemporary practice.
