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November/December 1999

If a developing agent can be famous—or even the foundation of a cult—then that’s the case with pyrogallol, or “pyro.” If discussions on the Internet are any guide, pyro also seems to excite the emotions; the very mention of pyro development almost invariably results in passionate disputes between those who claim it’s a magic elixir without which decent work can’t be done, and those who dismiss its virtues as myth and assert that it was replaced by better things decades ago. Leaving myth and legend aside, this article will report on tests and field work that have convinced me that pyro has a valuable place in the modern darkroom.

In most situations, with most currently available large format films, properly used pyro formulas produce negatives that make platinum prints equal to—and often superior to—those made from negatives developed in standard metol- or phenidone-hydroquinone developers. At the same time, these negatives can deliver superb silver prints. This is important because in standard developers like D-76 or HC-110 a negative with the proper contrast range for platinum printing will prove too contrasty for good results in silver. This deters some people from trying platinum. The need for an extremely long scale negative and therefore the commitment to a negative that won’t be good for silver printing form a stumbling block that makes the move to platinum printing more daunting than it should. At the very least, the intelligent use of pyro developers provides a safety net for experiments in the classic platinum medium without abandoning silver altogether. At best, pyro development can help you make better prints than you thought you could. But before we get into specifics, a little background.

Pyro formulas were among the first developers employed for silver-halide emulsions. They were the most widely used developers in the 19th century. However, pyro used as a sole developing agent is problematic. It delivers low film speed and unpredictable developing action, largely due to rapid oxidation and unpredictable staining (more on staining later). At first ammonia was used as an accelerator; later, a more reliable combination was found with sodium sulfite as a preservative and sodium carbonate as an accelerator. An enormous number of specific formulations evolved by the early 1900’s, usually personalized by individual workers.

Pyro can be thought of as a double-action developer. It reduces silver, as do more familiar developing agents, and it does so with extremely high acutance (apparent visual sharpness). But it is also a tanning agent, and negatives developed in pyro form an image not only from silver reduced to its metallic state, but also from an accompanying proportional stain, and a hardened, dimensional relief image in the gelatin itself. Many of the early variations in the pyro formulation were attempts to gain control over the staining action, which tended to be variable and hard to predict. Another approach used by some photographers sought to minimize the stain, leaving only the high-acutance silver image. This worked well with large negatives, giving high resolution and fine rendering of detail, but resulted in too much grain for enlarging. With the introduction of metol and hydroquinone developer formulas, and the general movement of photographers to small negatives printed by enlargement, the use of pyro all but disappeared.

There were holdouts, though—none more famous than Edward Weston. He used a venerable staining pyro formula known as “ABC” throughout his career, even though it already was considered old-fashioned when his career began. “Stain” doesn’t sound like something we’d want in our negatives, but the pyro stain is special. It’s not an overall “fog” effect, but, when it works right, is proportional to the silver so that the thinnest areas of the negative have just a little silver and just a little stain. Highlights have more silver, and proportionally more stain. When printed, both components of the image affect the response of the paper, resulting in a variety of printing characteristics that can’t be matched by a negative consisting of silver alone. Pyro may have been considered outmoded by the 1920s and ’30s, but Weston insisted on staying with it. The pyro myth and legend can partly be attributed to his discussions of it in his Daybooks. Few photographers (even those who treated the Weston Daybooks as a sort of Bible) actually used pyro, but most were aware of it as “something special.” One of its special aspects is revealed in the Mexico Daybooks where it is clear that Weston expected to be able to print his pyro negatives in either platinum or silver. What was going on?

The next big step in the pyro saga came in the 1980s, when Gordon Hutchings began intensive research into pyro formulations because of his dissatisfaction with standard developers. The end product of this experimentation was his “PMK Pyro” formula (see Hutchings’ The Book of Pyro [Bitter Dog Press, P.O. Box 2324, Granite Bay, CA 95746] for a full discussion of his research and findings). Hutchings’ goal was maximizing the pyro staining action while rendering it predictable and repeatable, and at the same time maximizing the acutance and edge adjacency effects that are part of the pyro “look.” His formula combines pyro with metol and sodium metaborate (formerly known by the trade name Kodalk, hence the “K” in PMK).

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