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Writer / Elizabeth Graves Photography / Elizabeth Graves
Vinegar-developed cyanotypes:
Non-Toxic Midtone Contrast Control
Elizabeth examines acetic acid development upon classic formula cyanotypes and disprove the myths about developing in vinegar.
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.
"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
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.
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Image above: This weak image formed after 6 minutes of UV exposure with water development.
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Image above: The same 6 minute exposure time using the same negative results in a fully exposed print with vinegar development.
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Image above: 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.
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Image above: Six minutes of UV exposure with vinegar development provides a wide range of tones on this modern facade.
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Results
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 one of the artists represented
here, to see more of her work, take a look at Elizabeth's gallery.
Blueprint to cyanotypes - Exploring a historical alternative photographic process
by Malin Fabbri and Gary Fabbri
A well illustrated step-by-step guide to cyanotypes.
A lot more information on the process, chemicals, coating, exposure, printing, making negatives, washing and troubleshooting is available in this book.
Strongly recommended for beginners
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