ABC Pyro

Mix the developer fresh as a working solution just before using. This is the way I recommend using ABC Pyro and give the working dilutions in the Formula section. 

By following these precautions you will avoid many, if not all, of the problems associated with ABC Pyro. 

Edward Weston s Variation The main difference between standard ABC Pyro and Edward Weston s variation is the dilution ratio. Weston diluted the formula with 30 parts of water. The result was a softer working developer with an even fuller than usual tonal scale. 

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... 

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