Pyrochatechin vs Pyrogallol Comparisons

[craigclu]

My scratch mix tanning developers have all been based on pyrogallol. This has been very limited to some P-TEA, 110 and 550 Pyro, Koch's experiments and a few things of my own. I only recently added catechol to my chem shelf.

Some experiences awhile back with diXactol and WD2D+ (which I believe are catechol based) seemed to be more compatible with my general use of VC papers. How interchangeable are these two developing agents? What are their general energy/tanning levels in relation to each other? I've come to enjoy the ease of use of glycol and TEA based concentrates. Are there issues related to these compatabilities that I should be aware of with the catechol? I've got some things working quite well but think I would like the less-green tones that the catechol based concoctions seem to produce.

 

[Claire Senft]

Pyrocat is a very inexpendive, very easy to use developer. I highly recommend ot to anyone...particulary thos poor souls using Rodinal.

 

[Claire Senft]

Pyrocat is a very inexpensive, very easy to use developer. I highly recommend it to anyone...particulary those poor souls using Rodinal.

 

[Claire Senft]

Pyrocat HD is a very inexpensive, very easy to use developer. I highly recommend it to anyone...particulary those poor souls still using Rodinal.

 

[Tom Hoskinson]

How interchangeable are these two developing agents? What are their general energy/tanning levels in relation to each other? I've come to enjoy the ease of use of glycol and TEA based concentrates. Are there issues related to these compatabilities that I should be aware of with the catechol? I've got some things working quite well but think I would like the less-green tones that the catechol based concoctions seem to produce.

Pyrogallol, Pyrocatechol (Catechol) and Hydroquinone are very closely related Benzine Ring compounds. All three reagents are potentially capable of producing proportional image tanning and stain. All three are additive or superadditive with Metol, Phenidone and Ascorbic Acid. The stain color produced is different with each of the three reagents. The effect of the stain is determined by the film type and the printing process used. It is difficult to judge what the effects will be by the visual appearance of the developed film

In terms of activity:

Pyrogallol is the most active (arbitrary scale 100%).
Pyrocatechol is the next most active (relative scale 70% Pyrogallol).
Hydroquinone is the least active of the three (relative scale 50% Pyrogallol).

I personally favor the Pyrocatechol based developers.

 

[rhphoto]

I just began developing again with WD2D+ and found the stain to be a bit greenish. Then when I began printing with my Ilford VC filters, I found that the stain was significantly affecting the ability of the VC paper (Kodak Polymax) to build contrast. And the high values were fairly well blocked, not something I'm accustomed to with Pyro. I was always under the impression that Wimbery's developer was Pyrogallol based. Anyway, my solution will simply be to go back to using graded papers. There was another very technical thread, about a year ago, dealing with the issue of stain and VC papers. The net result, it seemed to me, was that it was best to just avoid VC paper with Pyro.

 

[lee]

"There was another very technical thread, about a year ago, dealing with the issue of stain and VC papers. The net result, it seemed to me, was that it was best to just avoid VC paper with Pyro."

When I started using PMK, I used it with vc papers. I, too, found that the highlite seemed veiled or soft. I started developing the film longer in PMK and those issues went away. Then this year I switched to Pyrocat HD and use it with graded paper and Varible Contrast papers alike without any of the problems associated with PMK. I am sold on this developer to be used with vc paper. I have no experience with WD2D+.

lee\c

 

[Mehmet Kismet]

Hi,

To prepare a staining developer with a small modification from Sandy King's Pyrocat-HD formulae, I use hidroquinone instead of catechol which is hard to find in my country.

The result is almost indistinguishable from the original mixture.

Here is the formulae I use:
PART A
Distilled water 400cc
Sodium bisulfite 5g
Hidroquinone 25g
Phenidone 1g
Potassium bromide 1g
Water to make 500cc

PARTB
Distilled water 1000cc
Sodium carbonate anhydre 200g

To use with FP-4 4"X5" rated 64EI, and developed with a JOBO CPP-2 at the slowest speed, a starting point would be 8min at 22oC, for a diffusion enlarger head.
The mixture for this setup is 10ccA+50ccB+750cc water for N development.

My opinion is that is a combination worth to give a try.

Best
Mehmet Kismet

 

[Mehmet Kismet]

Hi,

I omitted in my post to mention that the given formulae is best suited to varicontrast papers then the pyrogallol based formulaes. For more contrasty highlights, that I prefer in my works, the brown color stain of the hidroquinon is better then the green-yellow stain of pyrogallol. This color of pyrogallol retains the magenta filter to soften the highlights where there is more stain and more green-yellow in the negative.

Best
Mehmet Kismet

 

[Tom Hoskinson]

Apart from stain color, catechol seems to work best in high PH solutions of sodium hydroxide, which precludes its use in TEA solutions...


Jay

That does not agree with my experience, Jay. In my experience, developers containing a combination of catechol and phenidone or catechol, phenidone and ascorbic acid work fine with a dilute solution of either TEA, Sodium Carbonate or Potassium Carbonate as the accelerator.

By the way, a dilute solution of Sodium or Potassium Hydroxide is not stable and will combine with the Carbon Dioxide in air to become Carbonate.

 

[sanking]

Tom,

I know that catechol developers work in carbonate solutions (Pyrocat HD), or TEA solutions (Cat-P-TEA) given enough time or concentration, but in my testing I get more activity from less concentration using sodium hydroxide as the alkali, which to me, is better. A dilute solution of Sodium hydroxide is stable enough to do its job in a one-shot working solution, so in this application its stability is not a factor. Incidentally, the biggest surprise I've found in this developer is the extremely fine grain. The conventional wisdom that high acutance, sulfite-free developers sacrifice grain for sharpness, but that doesn't hold true with this developer. I can't find grain to focus on with HP5+.

Jay

The hydroxides have been widely used with pyrocatechin based developers and it should come as no surprise that they give greater activity with pyrocatechin than the carbonates. In the Pyrocat-HD formula, to get to the same pH, and energy, you must substitute carbonate for hydroxide at about a 10:1 ratio. You could also substitute tribasic sodium phosphate at about the same ratio, or slightly less. However, there is a lot more to a good developer than its level of activity or energy.

When I developed the Pyrocat-HD formula I experimented with numerous activators, including the hydroxides, the carbonates, and TSP. Based on several criteria I concluded that the carbonates, in spite of the fact that they are not as efficient as the hydroxides, are a better and more rational choice for this developer. With carbonate the stock solutions are more stable, the working solutions are better buffered, and there is less chance of pin holes on the negatives, especially when using acid stop baths. Also, the grain is definitely finer in the Pyrocat-HD formula with carbonate.

So, while there is no doubt in my mind but that the hydroxides work very well with pyrocatechin based formulas such as Pyrocat-HD, and they are definitely more efficient in some respects, I simply don't think they are the best choice.

Sandy

 

[Kirk Keyes]

For more contrasty highlights, that I prefer in my works, the brown color stain of the hidroquinon is better then the green-yellow stain of pyrogallol.

Mehmet - "better" is a personal choice here - as the yellow stain of the pyrogallol may be better for someone elses contrasty subjects...

Thanks for the formula, I'll give it a try.

Kirk - www.keyesphoto.com

 

[Mehmet Kismet]

Mehmet - "better" is a personal choice here - as the yellow stain of the pyrogallol may be better for someone elses contrasty subjects...

Thanks for the formula, I'll give it a try.

Kirk - www.keyesphoto.com

Hi Kirk,

You are absolutely right. That is only my preference. When I precised that I prefer that developer for the contrasty highlights in my work, I ment the contrasty highlights on my prints, not on the subjects.
I agree with you that the pyro color flattens somehow the highlights on the multigrade papers, so if the subject itself is contrasty, the pyro could be a better choice.

Best
Mehmet Kismet

 

[Tom Hoskinson]

Hi Kirk,

You are absolutely right. That is only my preference. When I precised that I prefer that developer for the contrasty highlights in my work, I ment the contrasty highlights on my prints, not on the subjects.
I agree with you that the pyro color flattens somehow the highlights on the multigrade papers, so if the subject itself is contrasty, the pyro could be a better choice.

Best
Mehmet Kismet

Quite right! I maintain separate stock solutions of Pyrogallol, Pyrocatechol, Hydroquinone and Phenidone dissolved in Propylene Glycol which allows me to "tune" the developer if the situation requires it.