jdef said:Tom,
did you see any improvement over the original formula?
Jay
Michael Kadillak said:The pyrocat stain was clearly there but a but more of a neutral grey color as opposed to the classic Pyrocat HD brown, but it is not that big a deal.
DeanC said:I'll be curious to see what the impact of that is on printing with VC papers...
I get mine at Photographers' Formulary for about $35 a pound + shipping. Be sure to ask for the base, not the hydrochloride.john_s said:I'm interested in buying some p-aminophenol. Does anyone know if it also goes by the name of 4-aminophenol or 4-Hydroxyaniline (CAS 123-30-8)
Chemical formula 4-(NH2)C6H4OH
If it's the same thing, its price is not as steep as some developing agents.
Tom Hoskinson said:2 rolls of Efke 100 Rated at EI 100 and developed Semi-Stand in 1:1:100 Pyrocat (p-aminophenol) for 18 min at 71F
I have been able to print stain-only negatives on VC paper with maximum blue filtration, so you should have no trouble printing these. By stain-only I mean with silver bleached out by Farmer's reducer. I am presently waiting shipment of some catechol, but have tried the Pyrocat P and M with hydroquinone, which also stains well in them.Tom Hoskinson said:I performed blue channel and visual channel densitometry on the TMAX 400 and the Efke 100 and 25 negs. There is a significant stain induced density difference between the blue channel and the visual channel that is proportional to the exposure (as expected) so these negatives should contact print well on Azo. Regarding printing on VC papers, that will require some additional testing.
pauldc said:Tom, could you define what your semi-stand agitation cycle is. Your times are really interesting but as I am new to semi-stand development and there seem to be many different variations I just wanted to clarify the precise method before I try to duplicate it.
Many thanks!
The Handbook says the base is very soluble in hot water, but only slightly in cold. If you are preventing rapid oxidation in the working solution, you are not getting much stain, but you already know that. Too much sulfite will do that. I think you should try one batch mixed in glycol without sulfite. Add tiny increments of sulfite to the working solution to find the optimum trade between stain and activity. With most staining developers the stain is caused by oxidation products. Also you must remember that Sandy is searching for stain density in the UV region. A stain that is very dense in the visible blue may be transparent in the UV and vice versa.jdef said:Hi Pat.
Have you tried King's catechol-pap formula? I made some up as soon as he posted it, and have never seen it produce any significant staining. I'm using the pap base, for use with glycol, but wouldn't the hydrochloride be more suitable for an aqueous solution? I could only get even the very small amount of pap he calls for into solution by significant heating. King doesn't specify which form of pap he uses in his formula.
Regarding the sodium metabisulfite, it's true that we could leave it out of a glycol solution, but that would leave nothing to prevent the rapid oxidation of the working solution, which might have a real impact when using dilute solutions and extended development. How well would a small amount of sodium sulfite keep in a concentrated alkali solution? My own approach is to use a very small amount of ascorbic acid to preserve the working solution during development, at a ratio of 1:20 to the catechol. In my formula, the ascorbic acts as a secondary reducer, and a preservative of the working solution, simplifying the formula and making it compatible with glycol. The only advantage I can see in using an aqueous stock solution is that it's cheaper than glycol, which seems a false economy, given the shelf lives of the respective solutions, and we all have you to thank for that revelation.
Jay
gainer said:Tom, I believe it was you who once mentioned working on a TEA-sulfite complex that would be easily soluble in glycol or TEA. The sulfite content of the Pyrocat family is very important. Too little slows development and too much prevents stain. All other essential parts of these developers are soluble in glycol if you use the p-aminophenol base or the metol base or phenidone. If I had my druthers, I would leave out the bisulfite in the glycol solution. It isn't needed for protection. If it proved necessary, I would add it to the working solution, but it would be nice to have a way to do it like HC110 does.
clay said:Here are some sample measurements of Pcat-P with 400TX 1:1:100 12 min 69deg:
Vis 1.74
Ortho 1.88
UV 2.83
As you can see, this stuff has one of the strongest actinic staining responses I have ever observed.
I used a water stop and TF-4 fixer followed by hypoclear, wash and clear. I'm a buyer on this stuff. I like the grain pattern on Tri-X better than the original pyrocat-HD as well.
jdef said:I am certainly not getting the same density in Visual and Blue with Pyrocat-P as I do with Pyrocat-HD, and the differences between Vis. and UV you've posted for Pyrocat-P are dramatically different than what King has posted for Pyrocat-HD. Something seems amiss. Ah, the wonders and mysteries of staining developers.
Jay
jdef said:Sandy!
And I thought you didn't want to discuss this with me. If the problem was in my measuring equipment, it seems the same errors would apply equally to all developers tested, right? Incidentally, my measurements of Pyrocat HD are very much in line with your own, except that you report a little less fog than I see with that developer. The differences between Vis. and UV readings you've posted for Pyrocat HD at densities similar to the ones Clay posted for Pyrocat-P are dramatically different, and this takes me and my equipment/procedures completely out of the equation. It seems that something is still amiss.
Jay
jdef said:Sandy,
what do you know about my equipment and procedures? Very little, I think. Cast this issue in any light you like, and use any excuses that suit your fragile ego, but I know how to use a densitometer, and I know what I'm seeing.
Jay
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