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Cyanotype Variations

NOTE: NO CYANIDE COMPOUNDS SHOULD EVER BE MIXED WITH AN ACID

Traditional Mix:

Solution A:

25% ferric ammonium citrate (green scales)

Solution B:

10% potassium ferricyanide

mix equal parts A and B just before use, coat paper, dry, expose and develop by washing in water.

Source: Historic Photographic Processes - A guide to Creating Handmade Photographic Images, Richard Faber, 1998

Variation 1:

Solution A:

20% ferric ammonium citrate (green scales)

Solution B:

14% potassium ferricyanide

mix equal parts A and B just before use, coat paper, dry, expose and develop by washing in water.

>>> This is the formula that I use for my own work. 5-10 minute exposure to full sun depending on the density of the negative. See EXAMPLE

Source: Alternative Photographic Processes, Kent Wade, 1978

UPDATE 5/1/2007: After this year's lensless workshop we found we had to adjust the formula to 18% and 15% respectively to get good results. No idea why this was necessary this time and not in the past.

Variation 2:

Solution A:

22% ferric ammonium citrate (green scales)

Solution B:

16% potassium ferricyanide

mix equal parts A and B just before use, coat paper, dry, expose and develop by washing in water.

Source: Breaking the Rules, A Photo Media Cookbook, Bea Nettles, 1977

NOTE: Too little Potassium ferricyanide will result in color bleeding into the whites. Too much will cause the exposure to be longer. [in above formulas, the Traditional has the lowest ratio and Variation #2 the highest]

Single solution. Mix up just before use: [same as variation #1 above]

in 20ml of water add

2 grams of ferric ammonium citrate (green scales) and dissolve. Then add 1.4 grams potassium ferricyanide and dissolve.

Expose in a contact printing frame to full strength sunlight for 2-5 minutes. wash in water and dry.

You can intensify with 3% hydrogen peroxide or half strength household bleach.

Yet another:

Solution A:

25% ferric ammonium citrate
1% oxalic acid (or citric acid)
[this is a low enough strength of acid to not cause problems, but never add powder directly to a cyanide solution]

Solution B:

9% potassium ferricyanide
0.1% potassium dichromate (carcinogenic)

mix equal parts A and B just before use, coat paper, dry, expose and develop by washing in water.

Gives more intense blues.

PAPERS

The paper that you use has a huge effect on the resulting image. There is no way to predict the final result other than to try. Some papers produce mottled images from some aspect of the making of the paper. Some papers have trouble holding the emulsion [chemical solutions], whereas others will not clear on washing and later turn colors. Best if you can get a small sample first.

For paper I like to use Epson Double Matt Inkjet paper. VERY smooth finish and high resolution, resonable cost and faster washing than thicker art papers, but most fine art papers will work, as well as most cotton cloth. The smaller the 'tooth' of the paper, the higher will be the final resolution possible.

I have recently learned that different formulas work best with different papers. The above Epson paper works well with Variation 1, but not others.
 

Chris Patton, cpatton@stanford.edu