The following is a direct (and complete) quote from Howard Bonds article, Pyro Effects, Further Tests Show More, But Still Limited Effects published in Photo Techniques, September/October 2004.
Conclusions
Preparation of this article has shown me that pyro does indeed produce less-visible grain and greater edge sharpness, although the latter may not be apparent in moderate enlargements and with some subjects. I understand why pyros depression of high values appeals to photographers who are determined to use Tri-X, in spite of the lower contrast in the shadows inherent in its curve shape. I dont see how users of films with rather straight characteristic curves such as T-Max, FP4+, HP5+ and Delta 100 can embrace pyro, because of its depression of high values and loss of local contrast there. I have also become aware of a big obstacle to the comparison of two photographs of a subject when one negative is developed in pyro: there is no way to know what fraction of the stain is acting as a VC filter and what fraction is acting as neutral density. This makes it impossible to know what density range the pyro negative should have to match the other negative.
The fact that famous photographer A used pyro and made remarkable photographs is not a reason for choosing pyro. One can easily cite famous photographers B, C and D who used or are using other developers. No doubt all of them could switch developers and still make remarkable photographs.
Now that I am better acquainted with pyro, and since I dont use Tri-X, I see ample purely photographic reasons for ignoring it. There is no need to take into account the fact that 2 grams constitutes a fatal dose or the concern of my biochemist friends that pyro may destroy dopamine producing brain cells.
The first two paragraphs show me that in spite of his latest efforts, Howard is still out in the weeds. He clearly still doesnt grasp the real technical issues.
Howards last paragraph really annoys me. There is no need to take into account the fact that 2 grams constitutes a fatal dose
Overlooking for the moment that Bond cites no scientific data to support this human toxicity speculation, it implies that one would need to ingest an enormous amount of PMK Pyro working solution (at least 2 liters) if one were bent on pyro induced suicide by drinking PMK. In the process of drinking 2 liters of PMK, one would also consume 12 grams of sodium metaborate, plus 0.2 grams of Metol and 0.4 grams of sodium bisulfite. Then, of course, there are all the oxidation products, etc.
If you drank 2 liters of one of Bonds favorite developers, D-76 (diluted 1:1), you would consume: 5.0 grams of Hydroquinone - a very close (and toxic) benzene ring relative of pyrogallol, plus 100 grams of sodium sulfite, 2 grams of Metol and 2 grams of Borax.
When working with photographic chemistry, always practice chemical safety!
Protect your skin, mucous membranes and eyes!
Protect your respiratory system!
Dont ingest any of the processing solutions!
Oh, by the way: "...pyro may destroy dopamine producing brain cells"
Gee, I always thought that was the Amidol myth...
Conclusions
Preparation of this article has shown me that pyro does indeed produce less-visible grain and greater edge sharpness, although the latter may not be apparent in moderate enlargements and with some subjects. I understand why pyros depression of high values appeals to photographers who are determined to use Tri-X, in spite of the lower contrast in the shadows inherent in its curve shape. I dont see how users of films with rather straight characteristic curves such as T-Max, FP4+, HP5+ and Delta 100 can embrace pyro, because of its depression of high values and loss of local contrast there. I have also become aware of a big obstacle to the comparison of two photographs of a subject when one negative is developed in pyro: there is no way to know what fraction of the stain is acting as a VC filter and what fraction is acting as neutral density. This makes it impossible to know what density range the pyro negative should have to match the other negative.
The fact that famous photographer A used pyro and made remarkable photographs is not a reason for choosing pyro. One can easily cite famous photographers B, C and D who used or are using other developers. No doubt all of them could switch developers and still make remarkable photographs.
Now that I am better acquainted with pyro, and since I dont use Tri-X, I see ample purely photographic reasons for ignoring it. There is no need to take into account the fact that 2 grams constitutes a fatal dose or the concern of my biochemist friends that pyro may destroy dopamine producing brain cells.
The first two paragraphs show me that in spite of his latest efforts, Howard is still out in the weeds. He clearly still doesnt grasp the real technical issues.
Howards last paragraph really annoys me. There is no need to take into account the fact that 2 grams constitutes a fatal dose
Overlooking for the moment that Bond cites no scientific data to support this human toxicity speculation, it implies that one would need to ingest an enormous amount of PMK Pyro working solution (at least 2 liters) if one were bent on pyro induced suicide by drinking PMK. In the process of drinking 2 liters of PMK, one would also consume 12 grams of sodium metaborate, plus 0.2 grams of Metol and 0.4 grams of sodium bisulfite. Then, of course, there are all the oxidation products, etc.
If you drank 2 liters of one of Bonds favorite developers, D-76 (diluted 1:1), you would consume: 5.0 grams of Hydroquinone - a very close (and toxic) benzene ring relative of pyrogallol, plus 100 grams of sodium sulfite, 2 grams of Metol and 2 grams of Borax.
When working with photographic chemistry, always practice chemical safety!
Protect your skin, mucous membranes and eyes!
Protect your respiratory system!
Dont ingest any of the processing solutions!
Oh, by the way: "...pyro may destroy dopamine producing brain cells"
Gee, I always thought that was the Amidol myth...