Originally Posted by
sanking
First, in order to prevent this from becoming another divisive thread about the comparison of different pyro developers, I am going to lump them together and treat them as one, with the one exception of the color of the stain as it impacts compensation with VC silver papers.
There are several reasons why many people prefer staining developers.
1. Most of the popular staining developers, including Diaxactol, PMK, Pyrocat-HD, and WD2D+ are high acutance developers, at least when used at the right dilution. That is, they create very enhanced adjacency effects which increases apparent sharpness. Some non-staining developers (FX-2 for example) are also high acutance developers, but the tanning you get with pyro developers hardens the gelatin and encourages more precise development, which further enhances sharpness. Howard Bond, not an advocate of staining developers, did an article in PhotoTechniques a couple of years back, and even he concluded that the pyro developers he tested gave sharper results with some films than non-staining developers.
2. The stain masks the grain and gives a smoother, less grainy look that you get with other high acutance developers. For example, PMK and Pyrocat-HD are every bit as sharp as Rodinal, when used correctly of course, but the appearance of grain is much finer because of the stain.
3. The stain is proportional to silver density and is therefore greatest in the highlights. This results in a compensation effect with VC silver papers. Some people like the compensation, others don't, but as a rule I believe it is desirable when exposing negatives in very high contrast scenes. As a rule formulas that give a brown stain (PMK, Rollo Pyro) give less compensation with VC papers than yellow/green stain formulas (Pyrocat-HD, Diaxactol).
4. Stain is also very desirable with processes that require negatives of high CI since the stain adds contrast for both AZO 2 and for alternative processes.
5. Most of the staining developers have long shelf life and are also very convenient to use. They come in concentrated stock solutions which last for months or even years, and are diluted for use. This assures consistent results. Staining developer are also highly efficient in their use of reducers, which makes them much more economical than most other developers, especially those that require a lot of sulfite, D76 for example.
6. One disadvantage of staining developers is that the stain makes it more difficult to use sensitometry. This is not a great problem with graded silver papers, but with VC papers the application of sensitometry can be quite complicated. Lack of precision in the use of BTZS has been one of the reasons some BTZS users have avoided staining developers. However, as a BTZS proponent who uses only graded silver papers (AZO) and alternative processes I have not found any problem in obtaining precise results with BTZS and stained negatives.
Staining developers are not elixirs, or magic bullets, and the difference in results between them and other acutance formulas are not all that great, as a general rule. Unfortunately there are many myths out there about the properties of staining developers and it is sometime hard for a novice to sort fact from fiction. However, for persons who know exactly what they want in a developer staining developers offers some specific advantages that may be of some interest.
Sandy King
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