Christopher John Ball Fine Arts Photographer and Writer
A Short Introduction to the Cyanotype

History of the Cyanotype.
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The invention of the Cyanotype process is accredited to Sir John Herschel, the Astronomer Royal, in 1842. It is believed that he developed this process so as to be able to make accurate copies of his designs, calculations and notes. Prior to this process draughtsmen were employed to copy the work. Herschel became dissatisfied with the mistakes and inaccuracy that often arose and so the ' Blue-print ' came into being.

 

Though used mainly for copying drawings it did not take long for the process to be taken up by photographers after it was found that it could be used to produce prints from continuous tone negatives, provided that they exhibited plenty of contrast. The Cyanotype is a printing out process. It is one of the oldest and most permanent printing processes still in use by, amongst others, Fine Arts Photographers.

Method of Cyanotype Production

Formula One

Solution A:

Ferric Ammonium Citrate (green) = 20 grams
Water at 22 degrees centigrade = 100ml.

Solution B:
Potassium Ferricyanide = 10 grams
Water at 22 degrees centigrade = 100ml.

Formula Two

Solution A:
Ferric Ammonium Citrate (green) = 20 grams
Oxalic Acid (HIGHLY TOXIC) = 5 grams
Water at 22 degrees centigrade = 100ml.

Solution B:
Potassium Ferricyanide = 10 grams
Oxalic Acid (HIGHLY TOXIC) = 5 grams
Ammonium Dichromate = 2 grams
Water at 22 degrees centigrade = 100ml.

Home made printing frame

alternative printing 1 alternative printing 2 alternative printing 3

Method
Store solutions A and B, separately, in brown bottles (available from chemists and drugstores) in the dark.
For use mix together equal parts of A and B. 10ml of each (20ml in total) should be enough for 10 5x4 prints.

Stored separately solutions A and B will keep indefinitely. Once mixed the solution will keep for about 24 hours and should be kept out of U.V-light.

 

Water Colour Paper (300g weight) makes an ideal print base and can be coated in weak artificial light. It is important that you use a stitched brush, i.e. one whose bristles are not held in place by metal crimping. The metal can react with the solutions giving adverse effects. The Japanese calligraphy style of brushes are ideal.

 

Allow the coated paper to dry naturally as the solution will 'fog' if heat is applied. Once the paper is dry (please make sure that the paper is thoroughly dry, if not you could find your negatives bleached) the negative can be placed in contact and exposed to a U.V-Light source. Sunlight is still considered to give the best results and has the advantage of being free.

 

After exposure the print is 'developed' in running water. This will develop and fix the photograph. It is recommended that the water used in the final wash be slightly acidified with a few drops of hydrochloric acid. The print is then hung, in the dark, to dry naturally. Once dry the print will have oxidized resulting in the familiar brilliant cyan colour.
It is possible to speed up this oxidization process by bathing the print, after the final wash, in a weak solution of Hydrogen Peroxide.

Toning cyanotype prints

Cyanotypes can be toned to produce several different colours. Unfortunately the process of doing so can be a very hit or miss affair. Do not let this put you off as, with a little patience, experimentation and luck, the results can be well worth the time and trouble involved.

 

N.B.: If your are going to tone prints that you have previously produced and dried, before toning, soak the prints, briefly, in distilled water at room temperature.

Green:

Make a saturated, 20ml, solution of Ferric Protosulphate.
Add to this 4 drops of Sulphuric Acid and then dilute with an equal amount of water (20ml).
You should now have 40ml of toner into which the print can be immersed.
Once the desired tone has been achieved remove the print and wash in water.

 

Lilac-violet:

Place the print in a solution of borax and water.
Wash after the desired tone has been achieved.

 

Mauve, Grey and Red: This solution will produce all three tones. It's just a question of how long you leave the print in the solution.

There are no hard and fast rules to the length of time as there are too many variables. Therefore this has to be done by inspection and it does not always work, but when it does the results can be beautiful.
Print darker than usual and then wash for 10 minutes, then immerse in a solution of Copper Nitrate (into which a few drops of ammonia have been added - add drop at a time until the precipitate has redissolved.
This bath turns the print first mauve, then grey and then finally red.

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