Vinegar-developed cyanotypes: non-toxic midtone contrast control

Elizabeth Graves examines acetic acid development upon classic formula cyanotypes and disprove the myths about developing in vinegar, using vinegar in the cyanotype developer.

Writer and photography / Elizabeth Graves


There is quite a bit of conflicting information available about the impact of acidic water upon cyanotypes during processing. I have read that acid helps clear cyanotypes, that it makes cyanotypes blotchy, that it improves or impairs contrast, that it can ruin a good print… I had my doubts about some of these claims, and so elected to perform some tests and decide if acids could be useful in adjusting my own cyanotype prints using vinegar in the cyanotype developer.

“Direct experimentation is the best way to learn what works best for you with your existing working practices and tools.”

Selected references hint that acids can be beneficial

Part of the reason that I had my doubts about acid’s negative influence is that I used acidic water to clear prints in my earliest uses of cyanotype. The on-line article that introduced me to cyanotype basics (which is no longer available) recommended a few drops of sulphuric acid to help clear the prints. At the time, I compared clearing the prints in ordinary tap water against the acidified water, and determined that the acid seemed to speed the clearing (and resulted in more blue in the rinse water).

I have also enjoyed Richard Farber’s book, Historic Photographic Processes, which recommends the use of weak solutions of acetic or citric acid for contrast adjustment. The book provides persuasive sample step tablets showing the difference in contrast that are possible with different concentrations of acid development.

To truly know if acid could be useful to me in my working practices, I decided to try an inexpensive and readily available form of acetic acid: white vinegar.

Experimental conditions for the vinegar and cyanotype experiment

To test the effects of acid, I used the following materials and methods:

  • Paper: I used Weston Diploma Parchment for the prints.
  • Emulsion formula: I used the classic cyanotype formula, 1A:1B, double coated.
  • Negatives: I utilized digital negatives printed on Pictorico overhead transparency film, using an Epson Stylus Photo 1400. I do not employ any special curves.
  • Exposure: I used my homemade light box, which uses arctinic black lights. Exposure times were as noted with the sample images.
  • Development formula: For acetic acid development, I used undiluted white vinegar of 5% acidity, which I poured into a tray slightly larger than my prints. I used just enough vinegar to cover one print completely, rocked the tray gently, and allowed each print to develop for one minute. (I rinsed out the tray and used fresh vinegar after developing 8 – 10 prints.)
    For the “control” prints, I used a tray of plain tap water and gently rocked the tray to develop the prints for about one minute. (Note that my water department advises me that our tap water has a pH of 8.9.)”
  • Wash: I rinsed the prints briefly by hand, since the vinegar drains off the paper in a strange, sheeting fashion, and then washed the prints in an archival print washer with tap water (pH 8.9) for one hour.
  • Dry: I hung the prints on a line outdoors, and let them dry for about 24 hours in our high ambient humidity. I then brought them inside to finish drying in a heated room.
This weak image formed after 6 minutes of UV exposure with water development.
This weak image formed after 6 minutes of UV exposure with water development.
The same 6 minute exposure time using the same negative results in a fully exposed print with vinegar development.
The same 6 minute exposure time using the same negative results in a fully exposed print with vinegar development.
cyanotype in vinegar
Twelve minutes of UV exposure with water development provides a higher contrast image with fewer midtones and a slightly deeper shade of blue. These images demonstrate the different results that can be achieved using the same negative and reasonably short exposure times.
Vinegar developed cyanotype
Six minutes of UV exposure with vinegar development provides a wide range of tones on this modern facade.
 

Results of using vinegar in the cyanotype developer

The vinegar does two useful things in these experiments: it brings out significantly more midtone detail from my negatives, and provides a satisfying print in about half the exposure time water development requires. Water development, in comparison, provides a deeper shade of blue and higher contrast images, but requires longer exposure times. By adjusting the acidity of the water, I can adjust the levels of contrast and midtone detail in my prints without straying from the classic cyanotype recipe, and without resorting to more toxic substances (such as potassium dichromate) to adjust the contrast of my prints.

Vinegar is a simple way to adjust my cyanotypes in useful ways. I plan to use vinegar (or other forms of acetic acid) in my cyanotype printing practices more often.

Elizabeth Graves is an artist working with cyanotype, vandyke and collodion and a keen experimenter with all sorts of alternative photographic processes.

 
Learn more in the Cyanotype book
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Blueprint to cyanotypes – Exploring a historical alternative photographic process

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6 thoughts on “Vinegar-developed cyanotypes: non-toxic midtone contrast control”

  1. This article was tremendously useful – thank you, O Wise One! I’ve been slowly perfecting my cyanographic (?) technique. Vinegar works for me. My blues are deeper and the mid-range in my prints has expanded to my satisfaction – and delight. I’m finding a 1:1 solution of water and vinegar get the same results as straight vinegar. It might be analogous to how a few drops of hydrogen peroxide in water is as effective as a lot of it. It seems all that’s needed is enough vinegar to “dance” on the molecules of the finished print.

  2. It takes a powerful, concentrated mineral acid to release cyanide gas from Potassium Ferricyanide. Vinegar won’t do it. Also, the amount of Potassium Ferricyanide in an exposed cyanotype is very small. There is no danger of exposure to cyanide gas when developing cyanotypes in vinegar

  3. I too am interested in trying the development method using white vinegar, but I would also hesitate until I heard that this method does not produce toxic gasses while the print is in development.

    Has anyone found out the answer to this question?

    Thanks.

  4. I have also experimented with using oxalic acid in the development bath. About 0.2% oxalic acid (about one-half teaspoonful in a liter of water) reduces contrast by about one (or so) grade and reduces exposure time by about 1/3.

  5. I really like like the results from this method but Malin Fabbri in her book warns against using any acid solutions with potassium ferricyanide as it can release very toxic hydrogen cyanide gas. What I am uncertain of is whether this pertains to the liquid solution or the exposed cyanotype when immersed in the vinegar.

    I am no chemist so would like someone with more knowledge to advise me before I try this method.

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