by Ed Buffaloe
Ferric-silver processes fall into two broad categories--those which contain ferric ammonium citrate and those which contain ferric oxalate. Prints from the former are generally referred to as brown prints, sepia prints, or
Vandyke Brown (VDB); and prints from the latter are generally referred to as kallitypes. Some formulae contain both chemicals, however kallitypes generally require a developer whereas brown print is a printing out process.
Brown Print (Vandyke) Formulae
Today’s “standard” brown print formula adheres closely to the original formula patented by Arndt and Troost in 1895, and is found in a multitude of minor variations. The gelatin is often
omitted, since so many modern papers are already sized. The very similar formula from Cassell’s Cyclopaedia of Photography (1911) recommends mixing just prior to use, whereas the usual recommendation today would be to mix A, B, and C and let the solution ripen for a day or more, then add the mixture to warm gelatine. The oxalic acid formula substitutes oxalic for tartaric acid, but requires an alkaline solution to develop. The downside of this is that an alkaline environment can cause the formation of iron hydroxide. Since iron hydroxide is very difficult to remove, its formation is prevented by washing in a slightly acidic bath (a pinch of citric acid being added to the tray of water). When Bob Schramm tested four different VDB formulas, including the oxalic acid formula, he concluded that the standard formula produced the best results. Schramm did not test some of the more obscure early formulae provided by Dick Stevens in his definitive work Making Kallitypes.
Despite the fact that “Vandyke” has become established as the name for the brown print process, it is a misnomer. Well into the 1930’s, the process was referred to variously as “brown
print,” “sepia print,” and sometimes “Kallitype,” but never Vandyke. Cassell’s Cyclopaedia lists it under “kallitype” and refers to it variously as a “modified kallitype” or “water-developing kallitype.” The “Vandyke” process described in early 20th century photographic literature (see Cassell’s and Photographic Facts and Formulas)
was a photo-lithographic process wherein zinc plates were coated with an enamel consisting of fish-glue, ammonium dichromate, and chromic acid. The process, which was used primarily for copying maps, bears no relation to
the brown print process of Arndt and Troost. I have been unable to determine at what point “brown print” and “Vandyke” became synonymous. The Encyclopaedia Britannica of 1961 lists Vandyke as a ferric-silver process, so the usage was established by that time.
Frederick Reginald Vandyke joined the Survey of India in 1889 and retired as manager of the Photo-Litho office in 1923. Volume 10 of Current Science, dated October
1939, states under “Science Notes and News” on page 492, "A press note issued from Simla draws attention to the main activities of this Department of the Survey of India. ...
Of the original contributions of the Photo-Litho Office towards development of new ideas and modern methods, mention may be made of the direct zinc printing process now known throughout the
world as the 'Vandyke Process' which was evolved at this Office and is named after the late Mr. F. R. Vandyke, Manager of its Lithographic Branch, who was responsible for the
discovery." Frederick Vandyke died 24 June 1936. A memorial plaque was raised in the Photo-Litho office by those who served him naming Frederick Reginald Vandyke inventor of
the Vandyke process. [I am indebted to David Petersen for this information.]
A longstanding concern has been voiced about the archival qualities of the brown print. This is due to the fact that many early
brown prints did not last long, and my own experience bears this out. The modern consensus seems to be that, if it is
processed properly, the brown print will have the same longevity as any other silver process. For the brown print there are
four things to consider to assure print permanence: (1) removal of iron compounds, (2) sufficient fixing, (3) sufficient washing,
and (4) toning--not necessarily in that order. My personal experience tells me that toning is not optional. Untoned prints keep
fine in a closed box, but once exposed to light and atmospheric pollutants, they begin to deteriorate almost immediately.
I have always used a 5% solution of hypo (sodium thiosulfate) to fix brown prints, but Russ Young (who wrote the Kallitype article in Coming into Focus) told me that a 2% solution was more appropriate. At that dilution, I would think a liter would
only be good for maybe two or three 8x10 prints, but I don’t have a definitive reference on that. I prefer to use a two-bath fix regime, just to make sure.
According to Russ Young, removal of iron compounds in Kallitype is best accomplished by immersing the print for two
minutes (with continual agitation) in a 3% solution of citric acid, after all other processing is completed, followed by a one minute running water wash. For brown prints, Wynn White recommends continuous agitation in successive water baths, each
with a pinch of citric acid added. I have noted that the print is reduced somewhat during this washing process, but regains a
greater contrast range in the fix. If citric acid is not used in the wash baths, a final rinse in a 3% citric acid bath is a good idea for the brown print.
Washing should be thorough. Wash times can be reduced by a 3 minute immersion in hypo clearing agent with continuous agitation.
Various additives may be used with the brown print. Print colour can be influenced somewhat by the addition of a drop or two
of 1% gold chloride, 1% potassium chloroplatinite, 1% sodium chloropalladite, or 5% uranium nitrate. If a precipitate forms,
filter it out. Image colour is affected much more by final toning than by additives to the Vandyke solution.
Contrast is traditionally increased by the addition of a drop or two of various concentrations of potassium dichromate (1-5 %).
The strongest concentration gives about a one-half stop increase in contrast. Ferric citrate is more effective (see James
Thompson’s formula and the Photo-Miniature formula). 3 to 6 grams of ferric citrate can be substituted for ferric ammonium
citrate in the brown print formula. The ferric citrate rarely dissolves completely. To help dissolve the ferric citrate, the water can be heated to 140
° F and additional tartaric acid added. I generally stir the mixture for as long as I can stand it, then let it
sit overnight and filter out the remaining undissolved ferric citrate. The ferric citrate Vandyke formula can then be mixed with the standard Vandyke formula in various proportions to adjust contrast.
Alternatively, you can make a ferric citrate stock solution. Heat 25ml distilled water to 140° F. Add 3 grams ferric citrate and
stir. Add 0.5 grams tartaric acid and additional hot distilled water to 33ml. Stir. Allow to sit overnight and filter. To increase
contrast, 1 to 5 drops of this solution can be added per milliliter of Vandyke solution.
For ease of coating, I usually add a drop or two of 5% Tween-20 solution to each coat, and sometimes a drop or two of 14 baume gum arabic solution.
Very simple toners can be made for brown prints by making a 0.5% solution of citric acid and adding 10 to 20 drops of 1% gold chloride, 1%
potassium chloroplatinite, or 1% sodium chloropalladite. Not much metal salt is necessary for brown print
toning, since the silver particles in the print are very fine. These toners are usually used after the wash and before fixing, but may also be used after fixing, if desired.
Selenium toning is best done after fixing, since selenium tends to have a slight reducing effect which is much more pronounced if
toning is done before fixing. Simply mix 3 to 5 milliliters of Kodak Rapid Selenium Toner in a liter of water.