Van Dyke Brown
||This article contains instructions, advice, or how-to content. (June 2013)|
The solution is made out of a mix of three different solutions.
- Solution 1: Dissolve 10 grams ferric ammonium citrate in 30 ml distilled water.
- Solution 2: Dissolve 1.5 grams tartaric acid in 30 ml distilled water.
- Solution 3: Dissolve 4 grams silver nitrate in 30 ml distilled water.
Combine the 3 solutions and stir well. Add enough distilled water to make 100 ml of solution. The solution will keep for several weeks if stored in a cool, dark place.
Printing with Van Dyke Brown requires the use of a large format negative in the size of the desired print, a suitable substrate for coating and subsequent printing, and an ultraviolet light source, either sunlight or suitable bulbs. The substrate can be almost anything to which the solution will adhere. Watercolor paper is a good first choice, but trickier substrates such as metal, glass, or tile can be first 'sized' with gelatin or arrowroot to facilitate coating. The substrate is coated with solution under tungsten light, air-dried, and coated a second time, if desired, for a stronger image.
The negative is placed on the thoroughly dried coated substrate, and is then weighted with a piece of glass. Frequent printers often use a printing frame to ease the checking of printing progress without disturbing the registration, or alignment, of the negative on the paper. These printing frames also ease the printing of a second coat over the same image.
The glass-negative-substrate 'sandwich' is exposed to a source of UV light. UV bulbs offer more control and consistency of light than sunlight, but at greatly increased cost. Standard daylight fluorescents produce some UV light, but printing times may be very long. A good starting point for printing time is to check a region of your photo that is very light but should still show some tone or detail (a highlight), and note how long it takes to register this detail, and print as long again. The latent image now appears, although flat and lacking substantial shadow tones.
Processing the printed image
The image must now be washed, or cleared, in several changes of water to remove soluble iron and silver compounds. It is good practice to slightly acidify the wash water, as iron compounds are more soluble in acid. A pinch of citric acid, dab of vinegar or pineapple juice will do the trick. As the image soaks, white cloudy precipitate of silver chloride will appear from the reaction of silver nitrate with chlorine in the water. Continue to wash for a few changes of water after this cloudiness ceases to appear.
Fixing is best done with a weak, alkaline fixer of 5% sodium thiosulfate with a teaspoon of household ammonia per liter. The alkali slows the fixing process and prevents rapid bleaching of the image. Almost immediately, the tones of the image will change to a deep chocolate brown. Keep fixing until the whites appear clear; about 2 minutes, and finish with a second, clean fix if desired for thorough removal of salts that would fade the image. Use a fixer clearing bath of sodium sulfite to help remove residual fixer, and give the print an extended wash fitting the absorbency of the substrate, around 30–45 minutes for absorbent papers, or 5–10 minutes for gelatin-sized tile or glass.
Air dry the print without heat. High heat will change the color of the print to more neutral and weaken the shadows.
- The Book of Alternative Photographic Processes Christopher James
- The World Journal of Post Factory Photography Siegel et al.
- Vandyke notes