As announced earlier I have created a variation (actually two) on the Pyrocat-HD formula and they are currently being beta tested by some folks with experience using Pyrocat. This posting will serve notice to those persons that they are free to divulge any information they may wish about the formula, and/or to comment on their findings here or elsewhere. I originally intended to hold off a bit before making these formulas available to the public but for personal reasons decided to go ahead and do so today. I am satisfied that at the very least, I do not harm since both variations work at the same energy level as Pyrocat-HD and give very similar results, with some slight differences I will note below.
There are two variations. One, Pyrocat-P, replaces the phenidone in the Pyrocat-HD formula with p-aminophenol. That is the stuff in Rodinal and some folks believe it is the finest developing agent ever made. So think of this version as the Rodinal Pyrocat. The other version replaces phenidone with metol, which is used in about 80% of the most popular high acutance developers. Geoffrey Crawley believed that metol was superior to p-aminophenol in terms of acutance. So think of the Pyrocat-M variation as the Crawley inspired Pyrocat. In any event, both Pyrocat-P and Pyrocat-M are similar in terms of amount of reducer per liter of developer to some of the classical high acutance developers such as Beutler, FX-1 and FX-2 and Neofin Blue. Only Windisch contains significantly less reducer per liter. I have not compared the two variations to any of these formulas, but when I originally devleoped the Pyrocat-HD formula I made extensive comparisons with FX-2 and sharpness was idential with rotary processing so I am sure that acutance will be very high with both Pyrocat-P and Pyrocat-M.
The primary objective of the variations was to improve acutance with rotary agitation. Many people have observed that Pyrocat-HD gives sharper results with minimal agitation procedures than with rotary processing, and I agree with that observation. Although I dont understand everything about the chemical reactions I speculate that the synergism between phenidone and pyrocatechin is so strong that it restricts local exhaustion except when the film is allowed to rest, as with minimal and stand agitation procedures. I further speculated that the use of other superadditive reducers, such as metol and/or p-aminophenol, might result in better performance with continuous agitation as in rotary processing. After considerable testing on my part I now believe that both the p-aminophenol and metol variations do indeed give slightly sharper results with rotary processing. This is based on visual observation of the negatives at various magnifications with a microscope. The samples were contact printed used the USAF 1951 chrome on glass target so as to eliminate optical issues. I will try to post some scans of the samples at high magnification when I figure the best way to do it. As for grain, it is a very close call but it does seem to me that the original HD gives the tightest grain (about like D76 1:1), followed very closely by Pyrocat-M, and Pyrocat-P the most. But again, the differences are not great. Effective film speed is about the same with the three variations.
The metol version has proven particularly interesting to me. Some of you know that the original Pyrocat-HD formula contained metol rather than phenidone, and I have stated many times that in my opinion it gives slightly sharper results. However, that formula was based on the use of 10X as much metol as we have in the present Pyrocat-M solution. Yet the working solution is just as energetic as the regular Pyrocat-HD solution.
Another objective in working with the two variations was to closely approximate the developer activity and stain intensity of the Pyrocat-HD formula. This has been achieved so for all practical purposes, and verified with extensive testing with sensitometry, so you can use these two variations with the same dilutions and development times you use with Pyrocat-HD and the results in terms of approximate CI and shape of curve should be very similar, at least with the 1:1:100 dilution. This information should make it very easy for anyone with experience using Pyrocat-HD to experiment with either variation.
Let me add that to the point my only testing of Pyrocat-P and Pyrocat-M has been with rotary processing, and the only film Ilford FP4+.
Pyrocat-P
Stock A
Distilled Water at 120ºF 750ml
Sodium Metabisulfite 10.0g
p-Aminophenol 5.0g
Pyrocatechin 50g
Potassium Iodide 1.0g
Water to 1000ml
Pyrocat-M
Stock A
Distilled Water at 120º F 750 ml
Metol 2.5g
Sodium Metabisulfite 10g
Pyrocatechin 50g
Potassium Iodide 1.0g
Water to 1000ml
Be sure to mix the chemicals in the order given.
Pyrocat-P can be mixed in glycol if that is desired. Pyrocat-M must be mixed water unless you first change the metol to base, which is not all that complicated.
Stock B solution is the regular Pyrocat-HD solution.
The use of the potassium iodide restrainer is optional with Pyrocat-P and Pyrocat-M as both give lower B+F without any restrainer than Pyrocat-HD. However, someone who knows a lot more about developer chemistry than me suggested that it might improve sharpness slightly, so I threw it in. It certainly does not do any harm, but as to whether it serves the intended purpose the jury is still out in my opinion.
If you have any comments, questions or note anything in this message that needs correction I will be happy to address them this evening. However, I will be on vacation beginning tomorrow and will not have access to the internet. Which is a very good thing from time to time, and this is one of those good times.
Sandy
There are two variations. One, Pyrocat-P, replaces the phenidone in the Pyrocat-HD formula with p-aminophenol. That is the stuff in Rodinal and some folks believe it is the finest developing agent ever made. So think of this version as the Rodinal Pyrocat. The other version replaces phenidone with metol, which is used in about 80% of the most popular high acutance developers. Geoffrey Crawley believed that metol was superior to p-aminophenol in terms of acutance. So think of the Pyrocat-M variation as the Crawley inspired Pyrocat. In any event, both Pyrocat-P and Pyrocat-M are similar in terms of amount of reducer per liter of developer to some of the classical high acutance developers such as Beutler, FX-1 and FX-2 and Neofin Blue. Only Windisch contains significantly less reducer per liter. I have not compared the two variations to any of these formulas, but when I originally devleoped the Pyrocat-HD formula I made extensive comparisons with FX-2 and sharpness was idential with rotary processing so I am sure that acutance will be very high with both Pyrocat-P and Pyrocat-M.
The primary objective of the variations was to improve acutance with rotary agitation. Many people have observed that Pyrocat-HD gives sharper results with minimal agitation procedures than with rotary processing, and I agree with that observation. Although I dont understand everything about the chemical reactions I speculate that the synergism between phenidone and pyrocatechin is so strong that it restricts local exhaustion except when the film is allowed to rest, as with minimal and stand agitation procedures. I further speculated that the use of other superadditive reducers, such as metol and/or p-aminophenol, might result in better performance with continuous agitation as in rotary processing. After considerable testing on my part I now believe that both the p-aminophenol and metol variations do indeed give slightly sharper results with rotary processing. This is based on visual observation of the negatives at various magnifications with a microscope. The samples were contact printed used the USAF 1951 chrome on glass target so as to eliminate optical issues. I will try to post some scans of the samples at high magnification when I figure the best way to do it. As for grain, it is a very close call but it does seem to me that the original HD gives the tightest grain (about like D76 1:1), followed very closely by Pyrocat-M, and Pyrocat-P the most. But again, the differences are not great. Effective film speed is about the same with the three variations.
The metol version has proven particularly interesting to me. Some of you know that the original Pyrocat-HD formula contained metol rather than phenidone, and I have stated many times that in my opinion it gives slightly sharper results. However, that formula was based on the use of 10X as much metol as we have in the present Pyrocat-M solution. Yet the working solution is just as energetic as the regular Pyrocat-HD solution.
Another objective in working with the two variations was to closely approximate the developer activity and stain intensity of the Pyrocat-HD formula. This has been achieved so for all practical purposes, and verified with extensive testing with sensitometry, so you can use these two variations with the same dilutions and development times you use with Pyrocat-HD and the results in terms of approximate CI and shape of curve should be very similar, at least with the 1:1:100 dilution. This information should make it very easy for anyone with experience using Pyrocat-HD to experiment with either variation.
Let me add that to the point my only testing of Pyrocat-P and Pyrocat-M has been with rotary processing, and the only film Ilford FP4+.
Pyrocat-P
Stock A
Distilled Water at 120ºF 750ml
Sodium Metabisulfite 10.0g
p-Aminophenol 5.0g
Pyrocatechin 50g
Potassium Iodide 1.0g
Water to 1000ml
Pyrocat-M
Stock A
Distilled Water at 120º F 750 ml
Metol 2.5g
Sodium Metabisulfite 10g
Pyrocatechin 50g
Potassium Iodide 1.0g
Water to 1000ml
Be sure to mix the chemicals in the order given.
Pyrocat-P can be mixed in glycol if that is desired. Pyrocat-M must be mixed water unless you first change the metol to base, which is not all that complicated.
Stock B solution is the regular Pyrocat-HD solution.
The use of the potassium iodide restrainer is optional with Pyrocat-P and Pyrocat-M as both give lower B+F without any restrainer than Pyrocat-HD. However, someone who knows a lot more about developer chemistry than me suggested that it might improve sharpness slightly, so I threw it in. It certainly does not do any harm, but as to whether it serves the intended purpose the jury is still out in my opinion.
If you have any comments, questions or note anything in this message that needs correction I will be happy to address them this evening. However, I will be on vacation beginning tomorrow and will not have access to the internet. Which is a very good thing from time to time, and this is one of those good times.
Sandy
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