Pyrogallol and Pyrocatechin

It has been said that there is nothing that can compare to a full-scale black and white negative properly developed in pyrogallol (pyro). Whether this is true there is no question that negatives developed in pyro exhibit exceptionally sharp edges and delicate highlight detail. 

The classic pyro formula, known as ABC because it uses three stock solutions, is the oldest published formula still in use, dating to the 1880s. At one time or another, the formula was used by Edward Weston, Brett Weston, Ansel Adams, and almost any large-format photographer working in the first half of the twentieth century. There are several variations, the most notable being Kodak D-l, Ansco 45, and Defender 1-D, and different opinions as to the ratio of the three ingredients. 

ABC is one of the most fickle pyro formulas to use. It is usually recommended for large-format negatives because of graininess issues. However, used properly the results are subtle tonal gradation and delicate highlight separation. 

The Trouble with ABC The first problem is that when pyro is used as the sole developing agent, especially with low concentrations of sulfite, it tends to rapidly exhaust. As a result film developed 

The second problem is that the sodium sulfite in Solution B slowly changes to sodium sulfate when stored. The result is decreased protection from aerial and auto-oxidation leading to undesirable image stains. 

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The formula is given here as three separate working dilutions, 1 1 1 7,1 1 1 11, and 1 1 1 14. For the traditional ABC stock solutions see Chapter 6 Pyrogallol and Pyrocatechin. 

Phytochemistry Underground parts of the plant contains tannins and phenols (pyrogallol and pyrocatechin). The aboveground parts contain flavone glycosides, saponins, alkaloids, and tannins (12-27.2 %). The whole plant is rich in tannins (Chumbalov et al. 1968 Chumbalov and Bikbulatova 1970 Plant Resources of the USSR 1988). 

Phytochemistry The roots contains tannins (catechins, gallic acid, pyrogallol, and pyrocatechin), carbohydrates, and glycosides (Khalmatov 1964). The aboveground parts contain vitamins C, A, E, B, B, B, B,j, organic acids (malic and oxalic), sugars, fibers, hemiceUulose, pectin, and macroelements (Nuraliev 1989). Roots collected in Uzbekistan contained new phenylbutanoid and stilbene derivatives as well as the known compounds rhododendrol, epi-rhododendrin, lindleyin, torachrysone, etc. (Shikishima et al. 2001). 

Some readers may conclude that I have it out for JOBO rotary processors. Not at all. I highly recommend them for use with all color processes, C-41, E6, Ilfochrome, etc. They are also fine to use for paper development and negatives larger than 4X5 inches as long as sufficient volume of developer is maintained. They should never be used with developers that contain pyrogallol or pyrocatechin. 

Most of the chemicals used in black and white processes are safe and biodegradable. A few, such as selenium, pyrogallol, pyrocatechin, sodium hydroxide, and hydrochloric acid, require careful handling and disposal. Throughout The Darkroom Cookbook specific warnings and instructions will be given where appropriate. 

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