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Abstract
A useful developer can be formulated with pyrogallol if it is used in combination with Phenidone. The developer activity of the mixture is far superior to that of the individual components used separately, and closely matches the developer activity of Phenidone/hydroquinone solutions. A low pH formulation, consisting only of pyrogallol, Phenidone, and sodium sulphite (pH 8.30) yields a higher emulsion speed for the same development time than does a conventional fine grain developer like Eastman Kodak D-76. Since the pH of this developer is low, auto-oxidation is no problem and the developer is stable.
This paper discusses the superadditive effect of the pyrogallol-Phenidone developer and compares its activity with metol-pyrogallol and hydroquinone-Phenidone combinations. A stable, high pH, Phenidonepyrogallol developer is also described that makes use of ascorbic acid rather than sodium sulphite as the preservative.
Notes
The full text of this paper is published in The Photographic Journal, 105. 303 (1965).