Pyrocat HD vs PMK Stain

Hi Folks

Just made up my first batch of pyrocat hd to replace pmk. I dev'd two final rolls in pmk and then two in freshly made up hd according to the Sandy's formula. The two rolls I have dev'd in hd appear to be very nice but show no real stain at all and a little concerned that I may have done something wrong. Followed the advice given by Sandy for the full regime! HP5+ @250 1:1:100 in tanks for 15 mins @ 20c. I have just exposed a couple of sheets of 5x4 hp5 and going to give it ago in trays and see if it makes any difference - will try 2:1:100 as these negs are really for alt processing and so will probably give them around 16 mins! All chemicals used were fresh! The solution didn't change colour that I noticed as I mixed them up as pmk does?

Cheers, Carl

Pyrocat HD does not give as much general stain as PMK, so there is less stain visable to the eye. To the printing paper though, and that's what matters, there is plenty of stain. I wouldn't worry unless you have a problem printing.
juan

I think your times are a little long. I use both PMK and Pyrocat and the pyrocat development times are about 70% of the PMK development times. HP5+ 120 and LF are at 13 minutes (tank and tray) at 400 in PMK. About 8-9 minutes in pyrocat at 400.

I don't think it's the general stain so much that makes Pyrocat negatives look different from PMK - it's the colour of the image stain. My PMK negatives look greenish-brown, even in areas where there is significant image density. Conversely, my Pyrocat negatives look only slightly brown. I haven't yet done enough Pyrocat development to know if this is better or not.

PhotoJim said:

I don't think it's the general stain so much that makes Pyrocat negatives look different from PMK - it's the colour of the image stain. My PMK negatives look greenish-brown, even in areas where there is significant image density. Conversely, my Pyrocat negatives look only slightly brown. I haven't yet done enough Pyrocat development to know if this is better or not.

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That is also what I have found. Regardless of film there is a very distinct difference in color between PMK and Pyrocat-HD negatives. PMK negatives look greenish/brown or greenish/yellow and Pyrocat negatives look brown. In fact, unless you compare a Pyrocat negative to a non-stained negative you might think it had no stain at all as the brown can look almost neutral when viewed by certain light.

For graded silver papers and alternative processes the color of the stain is less important than effective printing density, which can be measured with a densitometer in the right mode. Visually a PMK negative looks like it has a lot more stain, and overall density, than a Pyrocat negative when both have the same effective printing CI. One would reach erroneous conclusions just eye-balling the negatives.

BTW, I have done a lot of comparison testing of these two developers recently, with four different films. Using rotary processing I have found that for the graded silver paper I am using (Ilford Galerie FB Grade 2) time of development is almost exactly the same for PMK (1:2:100) and Pyrocat-HD (1:1:100), and both are slighly less than Xtol 1:2 and D76 1:1. The ratio I have found is about 12 (PMK, Pyrocat), 13 (Xtol) and 14 (D76 1:1).

I have good reason to believe development times this will be qute different for VC silver papers since the color of the stain definitely impacts contrast in the highlights with these papers, but will wait for further comment until I have real data.

Sandy

Pyrocat-HD will give you stain only in build densities. Base has some fog as well but it is not visible. If your densities turned brown, higher densities are more brouwn, you're good. If you have step tablet developed in HD and let's say HC100 like I do, you will definitely see that fog is built only on exposed densities.

If you overexpose film, you will build considerable brown fog almost everywhere, you will get negative we call dense negative. Your DR will not change, but your highlight will be affected.

16 minutes are way too much, I agree with 8 minutes if your film is exposed normal. You see, final print does not require the best density range, it needs range your print can print best.

Give a try to perform some tests on your own. It's the best way to learn. I learned it that way, now I know what I am looking for.

Thanks folks...

I have just returned from a walk with the hound to find this info - just going to tray dev some 5x4 as I said earlier. Negs look good so I am not worried about the stain it was just glaringly different! Having rated the HP5+ 120 at 250 the negs look good at the time given. I'll report in an hour or so what has come from the 5x4 even though these are pinhole image and the longer exposures might make some difference!

Thanks again for your time and help, Carl

SAShruby said:

Give a try to perform some tests on your own. It's the best way to learn. I learned it that way, now I know what I am looking for.

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Pretty much happy with my pmk negs but wanted to try hd as it is less toxic - just enlisting the help of the enlightened before do a little more testing. Mind you only just found the new threads on pyrocat m & p - just as well I still have some chemicals ready!

5x4 Test Sheets

5x4 hp5 looking good too - 13mins might be a little too much but we'll see how they print on Saturday. Even the images made using the coca-cola pinhole cameras are looking good. No real stain visible again even with the 2:1:100 but as I said they look good to the eye - now just need to see what the uv makes of them

Thanks again all!

I too made the swap from PMK Carl and was puzzled by the fact that it doesn't change colour like PMK, DiXactol etc when mixing the two parts. The figures published are pretty well what I use in my jobo.

I hope to see some of your new images in the Galleries.

I haven't used the HD, but do like 510 pyro as it is a one shot process.

Mike