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  1. #21

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    Frank wrote:

    "Not having tried Pyrocat and being pretty experienced now with PMK, what does pyrocat do differently than PMK that I would want to try it?"


    PMK is an excellent developer. I used it myself for almost ten years as my primary develolper so I am very aware of its characteristics. Pyrocat-HD gives very similar results to PMK: high acutance, grain masking from staining, and high proportional stain. And the stock solutions also have very good keeping qualities, with a slight edge to PMK in this category. However, Pyrocat-HD has some characteristics, which may offer advantages.

    1. Pyrocat-HD can be used with rotary processing with no fear of uneven staining. I recommend it for rotary processing and have never had any reports that it caused uneven development or staining in this application.

    2. Pyrocat-HD can also be used with minimal agitation when processing roll film in tanks. This can give very pronounced adjacency effects and result in enhanced apparent sharpness. Pyrogallo based developers, on the other hand, are subject to uneven staining when processes with minimal agitation.

    3. Pyrocat-HD, even at the 1:1:100 dilution, requires shorter development times by about 25% compared to PMK to reach the same CI.

    4. Pyrocat-HD is less susceptible to fog from aerial oxidation and even with very long development times keeps a very low b+F. This make it very attractive for alternative printing processes that requires negatives of very high CI.

    5. Pyrocat-HD gives slightly greater effective film speed than PMK, when negatives are developed to the same CI. This speed gain is due to Phenidone.

    6. Pyrocat-HD is a better developer for making dual-purpose negatives, as for printing with both graded silver paper and Pt/Pd with the same negatives. This is because there is greater difference between the blue reading (to which silver papers are sensitive) and the UV reading (to which UV processes are sensitive) in a stained Pyrocat_HD negative than in a PMK negative.

    7. There is a difference in the way highlight values are rendered with Pyrocat-HD because it does not have the shoulder in the curve that one sees with PMK. This is neither a good thing nor a bad thing because the shoulder helps with certain scenes by providing compensation, but with other scenes it gives reduced highlight contrast. High mid-tone values are also rendered with slightly more contrast in Pyrocat-Hd for the same reason.

    Sandy King

  2. #22

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    Just wanted to mention one other thing. Pyrocat-HD also works with stand develoment when mixed at about 10:10:500. There is a new message on the photo.net forum from someone who got good results with Acros film and Pyrocat-HD in stand development.

    Sandy King

  3. #23
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    Sandy (or anyone else),
    can anyone suggest a starting time for HP5? I know the FP4 starting time is 9.5 minutes, but I'm changing to HP5 for my outdoor work for that extra stop. Also, does anyone one know of the comparable starting time when pyrocatHD is used at 75 degrees F instead of 70 as my house is kept at a constant 75 and this would preclue the need for temperature adjustment.
    Let's see what I've got in the magic trash can for Mateo!

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  4. #24

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    Quote Originally Posted by Jeremy Moore
    Sandy (or anyone else),
    can anyone suggest a starting time for HP5? I know the FP4 starting time is 9.5 minutes, but I'm changing to HP5 for my outdoor work for that extra stop. Also, does anyone one know of the comparable starting time when pyrocatHD is used at 75 degrees F instead of 70 as my house is kept at a constant 75 and this would preclue the need for temperature adjustment.
    Jeremy,
    Clay's article on the Unblinking eye site has some times for processing in the Jobo Drums.

    http://unblinkingeye.com/Articles/PC-HD/pc-hd.html
    George Losse
    www.georgelosse.com

  5. #25
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    is there a speed difference in the rotation of a unicolor 8x10 film tube on a unicolor rotary base vs the jobo expert drums? If there's not, then I'll just go with Clay's suggested time for the FP-4. Does anyone have one for HP-5?
    Let's see what I've got in the magic trash can for Mateo!

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  6. #26

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    Quote Originally Posted by Jeremy Moore
    is there a speed difference in the rotation of a unicolor 8x10 film tube on a unicolor rotary base vs the jobo expert drums? If there's not, then I'll just go with Clay's suggested time for the FP-4. Does anyone have one for HP-5?
    I've used Clay's times for FP4 on my Unicolor with good results. I don't have a densitometer tho.
    Nobody ever went broke underestimating the intelligence of the American public.

  7. #27

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    Jeremy wrote:

    "Is there a speed difference in the rotation of a unicolor 8x10 film tube on a unicolor rotary base vs the jobo expert drums? If there's not, then I'll just go with Clay's suggested time for the FP-4. Does anyone have one for HP-5?"

    Clay and I have had some recent correspondence on this and I hope he comments further.

    Basically, the Unicolor rotary base has just one speed, a fairly slow rpm, whereas the Jobo can be adjusted to very slow or fairly fast rotation. If you are using Job I recommend that the rpm be set to the slowest rotation the unit allows. If the rpm is set too high you may, and especially with high speed films like HP5+, get a fairly high b+f, or general stain. Slowing down the rpm reduces this possibility. It is less important with slow and medium speed films such as FP4+.

    Sandy

  8. #28

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    Donald wrote:

    "I substituted Sodium Carbonate for Potassium Carbonate since I already had it on hand for other uses. I spoke with Sandy King prior to doing this. The only change is I mix it in five times the amount of water for the stock solution. I then change the mix to 1-5-100. The reason is that Sodium Carbonate reaches solution saturation much more rapidly then Potassium Carbonate."

    Yes, I want to reiterate what Donald writes. At the same weight of dry chemical sodium carbonte can be substituted for potassium carbonate with no difference in development charactericstics. A Pyrocat-HD working solution of 1:1:100 using the recommended formulat of 100g of potassium carbonate per 100ml of water gives same results as a working solution of 1:5:100 using a 20% solution of sodium carbonate.


    Sandy

  9. #29
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    Just got back in from printing some HP-5/Pyrocat negs in palladium!

    Sandy and I have been corresponding on the Jobo issue, and I am now a total believer - the slower the better with pyrocat. It is not prone to streaking and uneven staining to begin with, so the the slow speed should not be a problem. What I was experiencing with higher speed films such as Tri-X and HP-5 was that the spent developer was almost muddy brown when I dumped it from the jobo, and the film rebate (edge) was stained a brownish/pinkish color. My printing times on some negatives was pretty long. Sandy suggested that too much aerial oxidation might be occuring due to my using the Jobo at the "F" setting, which is supposed to be the film setting. So I re-ran some tests for HP-5 at the 2:2:100 dilution and the absolute slowest speed setting, and voila - the problem disappeared.

    I have the test data and will post some times if you tell me what process you are using so I can use the proper target density range for your ideal negative. Coincidentally, Sandy also now recommends a full-spectrum (all channel) target density range for palladium at 1.3. I now concur with that heartily. My best print from the latest batch had exactly that range: shadow values at .25, highlights at 1.55. This also happens to be the perfect Azo/Amidol grade 2 density range. So you can have your cake and eat it too!

    Clay

  10. #30
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    Clay,

    I'm shooting 4x5 and will be developing in pyrocat-HD using a unicolor tube on a uniroller for silver enlargement from a color head. I'm hoping to use times at 75 degress F as that is the most common temperature at my house. Glad to know about the speed settings as I'm planning to use your FP4 time for my initial testings at 75 F after I order my chemicals.

    Also, I'll be in Houston/Galveston the weekend of August 8th. If you might have some free time to go shooting out on what you people who lack the ocean call a beach (that's my virginian talking out) please send me an email or PM. I'll be out on the island all day on Saturday and most of Sunday.
    Let's see what I've got in the magic trash can for Mateo!

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