Van dyke brown

Van Dyke Brown is an early photographic printing process. The process was so named due to the similarity of the print color to that of a brown oil paint named for Flemish painter Van Dyck.

Printing

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 a UV light source, either sunlight or suitable bulbs.The substrate can be almost anything that the solution will adhere to. 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 absorbancy of the substrate. I recommend 30-45 minutes in warm water for absorbent watercolor papers, and as little as five to ten 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.

Chemistry

Observe precautions for handling chemistry. Know your tools. Wear gloves and goggles if in doubt.

Like many photo processes, VDB is based on the light sensitivity of a salt, silver tartrate, which gives it a unique color and scale.

Formula:

*Part A:
**33 ml Distilled water
**9 grams ammonium ferric citrate green OR substitute
**18 grams ammonium ferric citrate brown
*Part B:
**33 ml distilled water
**1.5 grams Tartaric Acid
*Part C:
**33 ml Distilled water
**3.8 grams Silver nitrate

Silver nitrate can burn and causes VERY permanent brown stains on almost everything it touches. Stains won't be evident until exposed to UV light. Use caution.

Add part B to part A, and slowly add part C while stirring. Store solution in darkness in a tightly lidded glass bottle and age for a week. Solution keeps stable activity for years after ripening period.

References

"The Book of Alternative Photographic Processes" Christopher James

"The World Journal of Post Factory Photography" Siegel et al.

[http://www.alternativephotography.com/process_vandyke.html The Vandyke / Van Dyke Brown process]