The cyanotype is a very early photographic process invented by Sir John Herschel in 1842. The Herschels were an illustrious family. Sir John’s father was Sir William Herschel, first president of the Royal Astronomical Society and discoverer of the planet Uranus in 1781. As well as contributing to the early development of photography, Sir John also carried on his father’s astronomical work and was himself President of the Royal Astronomical Society on three occasions. John’s Aunt (William’s younger sister) was Caroline Herschel who also became an accomplished astronomical observer and discovered many new comets.
The cyanotype method is quite simple in principle; two chemicals (Potassium Ferricyanide and Ferric Ammonium Citrate), when mixed together become sensitive to UV light. A sheet of paper is coated with the mixture and the objects to be photographed placed on top, usually held in place by a sheet of glass. This is then exposed to UV light from the sun which causes a chemical reaction to take place in which the blue dye Ferric Ferrocyanide is produced. After washing in water, the exposed parts of the paper are seen to become a rich prussian blue. Those parts of the paper underneath the objects are shadowed from the UV rays and show as white and/or a paler blue. More recently, a modified method has been developed called the Wet Cyanotype process. This involves adding various liquids and powders to the coated paper before exposure to the sun with the intention of creating interesting textures and colour changes in the final image. The most effective of these modifiers I have found to be soap bubbles and vinegar. Others include salt, turmeric and lemon juice. What follows is not meant to be an encyclopaedic description of every aspect of making cyanotypes, rather a summary of what I have learned so far.
To get started, you will need the following materials:
- Watercolour paper
- Garden spray
- Distilled white vinegar
- Cyanotype chemicals
- Protective gloves
- Container for mixing chemicals
- Syringes for measuring chemicals
- Tray(s) for making soap bubbles and washing final print
1. Reasonably good quality artist’s watercolour paper such as that supplied by Windsor and Newton or Daler Rowney and others. I usually get mine from Hobbycraft, but any supplier of artist’s materials will stock something suitable. So far I have worked with A4 sheets exclusively, as this provides enough space for working on and I can scan the final results on my home multifunction printer/copier/scanner.
2. A garden spray bottle for adding vinegar. I find these from Hozelock give a good even spray but anything similar may work just as well.
3. Distilled white vinegar.
4. The two cyanotype chemicals Potassium Ferricyanide and Ferric Ammonium Citrate. For convenience, I use the kit supplied by Jacquard, available here. Each kit is sufficent for 60-70 A4 prints. If you plan on doing lots of large prints or coating fabrics for example, it will be cheaper to buy the raw chemicals, available here.
5. Protective gloves.
6. A container for mixing the chemicals. I use an old yoghurt pot.
7. A couple of syringes or other means of measuring equal volumes of the two chemicals.
8. A brush or brushes for applying the chemical mixture to the paper. Japanese Hake brushes are often recommended for this, available here.
9. Plastic tray(s) for producing soap bubbles and washing the final print. I bought a set of three used Paterson developing trays from eBay for about £15.
10. One or more old picture frames for holding the paper and objects in place during the exposure. Clip frames are cheap and widely available. The frame should be slightly larger than the size of paper you intend to use to allow space around the edge for placing the clamps. I covered the edges of the glass with electrical tape to prevent sharp edges.
11. Four clamps per frame for holding everything in place during the exposure. I got mine from Amazon here. Instead of using a sheet of glass, objects can also be held in place using a sheet of clingfilm which can impart an interesting texture of it’s own to the final image.
The process I use goes as follows:
1. Mix equal volumes of the two cyanotype chemicals together sufficient to coat one or two sheets of A4 paper. Coverage depends on the absorbancy of the paper you are using; I find that about 2ml of each solution is more than sufficient to cover one A4 sheet. I do this in a shady part of my garage, out of direct sunlight, as once combined the chemicals become sensitive to light. Complete darkness however is not required. Wear protective gloves and a protective apron or old clothes as the chemicals stain and can be hard to remove.
2. Paint the mixture onto the paper using a brush. I generally cover the whole sheet evenly or you can just paint over the middle part of the paper leaving a ragged edge of brush strokes and a white border for a more arty hand-crafted type look. Some people then leave the paper to dry overnight in a dark place. However, I proceed directly on to the next stage while the paper is still damp.
3. Unless the composition is extremely simple, such as a single leaf, I like to place the materials I am going to use on a separate piece of plain A4 paper first until I get an arrangement I am happy with. I then transfer the items carefully one by one onto the sensitised piece of paper.
4. Next comes the fun bit of adding soap bubbles, vinegar etc to the paper. For the bubbles, there are a couple of ways to do this. One is to prepare a tray of soapy water and place the paper sensitized side down in the bubbles and then lift it out. Hopefully it will now be covered with a uniform coating of bubbles, however this is rarely the case and some manual redistribution will be required. The objects can then be placed on the soapy paper. Another way is to coat the glass sheet that will be placed on top of everything with the soap bubbles before putting that in place. Or you could do a bit of both. Whatever method is used, I spray the bubbles with a few squirts of neat distilled white vinegar from a garden spray bottle. This appears to generate the nice orangey brown tones which appear in the final print.
5. Other things can also be added at this stage. Turmeric is a popular option and leaves a bright yellow mark on the print. I tend to use this sparingly if at all, as it can overpower the final image. I make it into a paste with a little water and then drip or spray it onto the paper using an old toothbrush. Salt sprinkled over the surface of the paper at random can also give a nice effect.
6. When all the materials have been added, cover with a sheet of glass (or clingfilm), place clamps round the edge of the frame and place in the sun to cook. I generally expose for at least 2 hours on a clear sunny day, maybe twice that if it’s cloudy. This is another area for experiment; I once made a test strip, gradually uncovering the paper a few centimetres at a time to give a range of exposure times. I found the final image got darker up to about 2 hours of exposure and times above that made little difference. Longer exposure times allow more UV to penetrate the objects covering the paper and so give more detail of the structure of a leaf for example. Shorter exposure times tend to produce a plain white silhouette of the object. If in doubt, overexpose. Some people leave cyanotypes exposing for many hours to great effect.
7. Once you have decided the exposure is finished, remove the glass sheet and the flowers, leaves etc from the paper and place it in a tray containing cold water for 5-10 minutes, agitating frequently. If I have used turmeric, I find this tends to stick to the paper and I have to gently brush it off during the wash.
8. After the wash, I place the paper flat on the ground and photograph it from above to make a record of the colours and tones of the image at this stage of the process. These are usually quite different from the final result once the paper has dried and been exposed to the air for 24 hours, as the colour of the print will become a deeper blue over time as the chemicals oxidise.
9. After washing, the print can be left to dry and will attain its final colour after about 24 hours. Alternatively, the oxidation process can be speeded up by soaking the print in a bath of dilute hydrogen peroxide for 1-2 minutes. I use 5ml of 3% hydrogen peroxide in 1 litre of water. The print will quickly develop the characteristic deep prussian blue colour after which it should be washed again in cold water and left to dry.
10. Once dry and fully oxidised, I scan the print and import the image into Adobe Lightroom where I can make final adjustments to bring out the colours, contrasts and tones in the image. I have also begun to process in Lightroom the image taken immediately after the wash stage, as sometimes I may prefer the colours and contrasts as they were at that stage.
So why not have a try? I have described my process for making prints on watercolour paper but many other surfaces can also be used including various fabrics, stone, glass, wood, leaves and even eggshells. If you don’t like the typical cyanotype blue of the finished print, you can bleach it and tone it with various types of tea or coffee for a more muted look. And that’s before you get started on contact printing photographic negatives printed out on to acrylic sheets.
For further information, the website Alternative Photography is excellent.
Finally, for anyone who wants the ultimate in detail about the history, chemistry and practice of making cyanotypes. I recommend Mike Ware’s website, especially his exhaustive document Cyanomicon in the downloads section.
You can view a selection of my Cyanotype images here.