PMK verses Pyrocat-HD

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Originally Posted by noseoil

" If understand all correctly, For graded papers I should see no difference between finished prints using either PMK or Pyrocat-HD. The differences are all in the process." rob

Rob, you will see a large difference in the shdow values. Try both to see how they look, then please write back and let us know which types of shadows you enjoy most. After having done both, my hunch is that it will be pyrocat. tim

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And this is definitely the case for graded paper? Yes?

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Originally Posted by ongarine

I'm an happy and satisfied user of Pyrocat MC and this suggestion to make a sort of "Pyrogallol MC" is very interesting.
If I understand well you have to mix, for the Pyrogallol formula, the same amount of catechol + 2/3 of the weight for Pyrogallol formula.
At the end for one liter of stock solution, as the original formula for Pyrocat MC called for 100 grams of Catechol, it will be 150 grams of pyrogallol to mix Pyrogallol MC.
Am I right Pat?

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No, no! Use 2/3 the weight of pyrogallol in place of the catechol. So, instead of 100 grams of catechol use 67 grams of pyrogallol. Metol and pyrogallol are the only developing agents, not counting the small amount of ascorbic acid.

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Originally Posted by dslater

This is true, However, you can use PMK in a rotary processor quite successfully with a couple of changes to the process - I process FP4+ in a Jobo 1521 tank with the 1509N reel all the time. I have had to make 2 adjustments to get this to work consistently.
First, use a lot of developer - for me a minimum of 500ml - this is the most I can put in my tank. Second, break up the development time into more than one batch - For example, if my development time is 10 minutes, I'll mix up 2 500ml batches of PMK, start the development with the first one, then after 5 minutes, dump that one out and put in the second batch for the remainder of the time - I find that at 70 deg F, I get the best results if I don't let a batch go for more than 5 -5 1/2 minutes.
Finally, - I add a very small amount of EDTA to promote even development - this is actually specific to my particular tank and reel - people using the expert probably drums don't need to do this - I got this info from the latest edition of "The Book of Pyro"
I also don't use the after-bath. It's interesting that even though Gordon no longer recommends the after-bath, it's still in the latest edition of his book.
I also don't see a lot of general stain on my negatives. In fact, when I got some Pyrocat-HD, I went out and shot multiple negatives of the same subject, then developed some in PMK and some in Pyrocat-HD. When I compare the negatives visually, my PMK negatives don't appear to have any more general stain than the Pyrocat negatives do - of course since I don't have a densitometer and I don't do alternative processes, it is entirely possible that there is more general stain, but I just don't see it visually or when I'm printing.

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The easiest way to evaluate image stain (presence or abscence of stain) is with a transmission densitometer. Visual evaluation of the negs can be very
misleading.

The second way of evaluating image stain is the Pat Gainer recommendation of bleaching out the silver image - thus leaving any stain image behind.

BTW, I am a Pyrocat-MC user. Most of my development is with minimal or semi-stand agitation. BTW, I get excellent results with Sheet film. 35mm and 120 roll film as well.

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Originally Posted by gainer

No, no! Use 2/3 the weight of pyrogallol in place of the catechol. So, instead of 100 grams of catechol use 67 grams of pyrogallol. Metol and pyrogallol are the only developing agents, not counting the small amount of ascorbic acid.

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So, 133 gr. of Pyrocat instead of 100 gr. of pyrogallol will do well too?

Philippe

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Originally Posted by Tom Hoskinson

The easiest way to evaluate image stain (presence or abscence of stain) is with a transmission densitometer. Visual evaluation of the negs can be very
misleading.

The second way of evaluating image stain is the Pat Gainer recommendation of bleaching out the silver image - thus leaving any stain image behind.

BTW, I am a Pyrocat-MC user. Most of my development is with minimal or semi-stand agitation. BTW, I get excellent results with Sheet film. 35mm and 120 roll film as well.

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Yes - but I was talking about the general stain - not the image stain. My observations on general stain were based on the appearance of deep shadows and the unexposed edges of the film.

Isn't it true that when one substitutes various chemicals in a formula, you are really formulating another developer? Is the pyrocat hd still pyrocat hd if you substitute ANY of the chems for another? Isn't that what happened when Sandy King introduced the various changes in the original Pyrocat HD?

lee\c

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Originally Posted by dslater

Yes - but I was talking about the general stain - not the image stain. My observations on general stain were based on the appearance of deep shadows and the unexposed edges of the film.

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IMHO,transmission densitometry is the best way to evaluate stain - both image stain and general stain.

And, if you bleach the developed film the stain (if it exists) will remain.

Preservation of both Deep shadow detail and Highlight detail is a particular attribute of the Pyrocat family of developers.

Let's try and correct the record.

Staining developers are an asset for both VC and graded papers. The yellow-yellow green - orange brown stain with PMK retards blue and green light. The stain with PMK is proportional to the silver density. VC papers are sensitive to both blue and green light and graded papers are sensitive to blue light. The color of the stain retards the transmission of blue and green light and thus is effective for both types of papers.

Shadows with PMK are not muddy if the proper exposure is given to the negative. You should always test for your personal EI - however you do the testing you should aim for a zone 1 density of .1 above fb+f.

I did a test a few years ago with PMK and Pyrocat. I tested for EI and dev time for a vc paper with no filter - approx the same as a #2 filter. I then shot side by side comparisons, processed the film and made direct scans of the negatives. The PMK negative had much better high value separation. I would have been happy to change developers if the Pyrocat gave me better tonal separation up and down the scale. I did not feel it did.

If you have not read The Book of Pyro by Gordon Hutchings I would strongly recommend doing so. It is the most definitive and comprehensive work on staining develpers and how they work. You can get a copy form Bostick and Sullivan or the Photographer's Formulary. Gordon will also be doing a workshop and a presentation on staining developers at foto3.


steve simmons
www.viewcamera.com

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Originally Posted by palewin

I was hoping Sandy King would reply to this thread, as he is the developer of the Pyrocat family of developers.

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Given that the thread title was "PMK versus Pyrocat-HD" I decided it best to not make any substantive comment comparing the two formulas. To the extent possible I would like to avoid entanglement in any more pyro wars, which I put more or less in the category of bad wine That is, if I never have any more of it in this lifetime I have already had enough for this life, and for all eternity.

Sandy King

well thats a pity. I'm not asking which is best because there is no such thing. I am asking what is the difference on only graded papers between the two developers. I would be more than happy to know one is better for highlight separation and one is better for shadow separation because that would give me two different tools for two different requirements. But if they are both very similar then I will only test one (for now).
So far I've a couple people say there's no real difference in the print and one person say there is a major difference. That leaves me having to test both developers.