Cyanotypes

Formula:

Stock Solution A: Ferric Ammonium Citrate (green) 25 grams Distilled Water (room temperature) 125 ml

Stock Solution B: Potassium Ferricyanide (orange) 17 grams Distilled Water (room temperature) 125 ml

Solutions are light sensitive and should be stored in brown bottles away from light. Shelf life is 2-4 weeks. These chemicals are poisonous, so wear gloves when handling them, particularly when coating or developing the print.

Preparing the solution:

Select a good grade of artist’s paper which will hold up under soaking in water: Arches watercolor, Rives BFK, Strathmore Drawing, etc. Under a 100 watt yellow “bug light” mix equal proportions of Stock A and Stock B together shortly before coating. Once mixed their shelf life is 1-2 hours. 10 ml of A and 10 ml of B to make 20 ml will easily coat a 16x20” piece of paper (or 3-4 8x10”.) Measure amounts with a small graduate cylinder and pour into a larger plastic beaker or wide mouth container.

Coating the paper:

Under a yellow “bug light,” brush the solution on to the paper with a wide 2-3” inexpensive, reusable foam brush. For an even coating, brush the solution on to the paper in horizontal, then vertical, then horizontal strokes. Dry flat on newspaper or hang on a line with clothespins in the dark. A hair dryer can speed drying if the heating coil doesn’t glow.

Coating fabric:

Use 100% cotton that has been washed to remove the sizing. Cotton/Dacron fabrics will not absorb the solution and sized cotton will produce mottled results. Float fabric in tray of sensitizer, wring gently wearing gloves and hang to dry in safelight or dark.

Exposure:

For best results, expose paper within 2 hours of drying. Expose sensitized paper by contact printing in full sunlight between 11am and 4pr for best quality blue. During exposure the paper will begin “printing out” revealing an image in a blue-gray color. Print by inspection or test strips until there is detail in the highlight areas (zones 7-9), for some of this faint detail washes/bleaches out during development. Development:

Develop the blueprint in a tray of running water (room temperature), periodically dumping it and refilling, for 5-15 minutes or until the yellow stain (unexposed solution) is was away front he highlights. You might wish to add a few drops of Clorox or Hydrogen Peroxide to the wash water after 5 minutes and soak the print in it for about 30 seconds. This will oxidize (intensify) the blue color and helps neutralize the alkalinity of the tap water, which bleaches the highlight detail of the print. After this intensification step, wash the print for another 5-10 minutes to complete development. Hang print to dry.

Toning Cyanotypes:

Any alkaline solution will bleach out your image: Borax, Dektol, Kodalk will produce interesting faded effects when diluted with water. Ammonia will produce interesting violet tones and try orange juice for wacky subtle colors. Cyanotypes can also be toned green, brown or black, but the results are disappointing; the formulas call for obscure chemistry and the prints are usually stained and impermanent. Check out The Book of Alternative Photographic Processes by Christopher James for toning solutions.

Troubleshooting:

Problem Solution Blue floats off paper during development, Under exposure or Ferric Ammonium tray full of blue ink Citrate solution is old or light struck Blue color is dead and purplish, highlights Overexposure or solution is old are stained, poor contrast, veiled with blue Blue is ok but not deep or saturated Solutions too new. Let age 3 days after mixing from powder Image looks glazed over, no depth, milky Incompatible paper or too much sizing. haze Soak in warm water before coating to remove sizing Stock Solution A (green) gets mold or Inevitable sign of age. Chemical impurities “seaweed” in it in dry chemistry. Try adding a pinch of ammonium dichromate as a preservative or filter out “seaweed” or discard after 2-4 weeks Image is blotchy, mottled, uneven Paper is too absorbent. Try another paper saturation or size with Knox Gelatin

Cyanotype Kits are available from Photographer’s Formulary www.photoformulary.com and Freestyle Photographic Supplies www.freestylephoto.biz.