johnnywalker said:
Not exactly. You were circling the wagons in your white truth-seekers robe, waiting for Sandy to show up so you could bring out the knife hidden in the folds of the robe. This medieval behaviour would not be tolerated in the Church of Rodinal. Maybe we can borrow their merry band of inquisitors to send you to the Attitude Adjustment Centre, where the proper dosage of your meds can be refined.
Jay DeFehr was clearly, at least IMHO, engaged in trolling, and that lead him to post a lot of misinformation that distorted the facts and completely misrepresented the information I have posted comparing Pyrocat-HD with Pyrocat-P. But the thing that surprises me the most is that someone would post misinformation that is so easily disproved by simple testing. If we were dealing with some type of esoteric theory about the formation of edge effects it might be possible to get away with this type of nonesense, but in this case the developer formulas are there to experiment with and test as one choses.
Prior to posting the Pyrocat-P and Pyrocat-M formulas I made numerous comparison tests with Pyrocat-HD and the formulas were specifically adjusted to produce similar intensity of stain for any given time of development. And there is no question about this fact. For a given time of development density reading will be virtually identical in V, B, and UV mode.
There is indeed a difference in the stain between any of the three Pyrocat variants and most pyrogallol based formulas, and the difference depends on whether the measurement is made with V, B, Ortho or UV. Pyrocat-HD negatives have a greater difference between the UV and Blue reading than pyrogallol developers, but less between V and B (or Ortho). This is an important point that I have made for years. See, for example, the comparison curves of Pyrocat, PMK, Rollo Pyro and WD2D on page three of my article Introduction to Pyro Staining Developers at
http://unblinkingeye.com/Articles/PCat/pcat.html
The difference in the intensity of the stain is a fact of some consequence because it explains why Pyrocat negatives function more like traditional negatives (or perhaps better stated, somewhere between traditional non-staining developers and pyrogallol based developers) with VC silver papers. For any given Visual density they will print with greater contrast and less compensation in the highlights than PMK and most other pyrogallol developers. And the difference between Blue and UV density also explains why Pyrocat is so efficient for dual-purpose negatives, i.e. for printing with both regular silver paper and with processes that uses UV light.
I can understand why persons with no experience with staining developers might look at a Pyrocat stained negative and conclude that there is not much staining compared to the heavy stain seen with many pyrogallol based developers. In fact, it happens all the time and I have repeatedly stated that visually Pyrocat negatives may appear almost neutral in color.
Below I provide some comparative data of Pyrocat-HD and Pyrocat-P negatives that were developed identically, i.e. same type of agitation (in tubes on a motor base), temperature (72F) and post-developer treatment (water stop bath, TF-3 fixer). Film was FP4+, dilution was 1:1:100. BTW, and time of development was ten minutes. This particular batch of FP4+ is several years old, which explains the slight elevation in B+F. My tests show that compared to fresh film it has developed with age an additional B+F of about 0.05. This of course has an exagerated impact on UV readings so in practice with fresh FP4+ film one should expect much lower B+F values.
For the data below I took readings through V, B and UV at Steps 1, 11 and 21.
Pyrocat-HD
Step 1, V=.13, B=.15, UV=.32
Step 11, V=.76, B=.88, UV= 1.32
Step 21, V=1.53, B=1.73, UV=2.25
Pyrocat-P
Step 1, V=.12, B=.14, UV=.28
Step 11, V=.75, B=.83, UV= 1.25
Step 21, V=1.55, B=1.75, UV=2.26
As you can see, these results are virtually identical. Data for the Pyrocat-M variant is very similar. These tests were repeated several times so as far as I am concerned the results have high reliability. Water quality, assuming you use tap water for mixing your working solution, could account for more or less stain density, but logically one would expect similar increase or decrease with both variants. Howeve, if you compare Pyrocat-HD with either Pyrocat-P or Pyrocat-M for stain density and don't get similar results I would suggest that something is either wrong with your chemicals or with your procedures. In DeFehr's case, where it is claimed that there was virtually no difference between V and B mode measurment, the most likely reason for this result IMO is either too much p-aminophenol or too much sulfite in the working solution. Both conditions would reduce or kill the stain. How could this happen? It could happen with a simple mistake in measurement, or it might result from making a measurement with a scale that lacks sufficient accuracy for the task.
Bear in mind that the purpose of creating the variants was not simply to replicate the stain intensity, but to replicate the stain intensity in such a way that the more important developer characteristics, i.e. sharpness and film grain type, could be observed and compared with negatives of very similar contrast at all points on the curve.
Sandy
