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  1. #21

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    Keeping in mind that this process will not give you as black a black as gelatine prints, your print looks pretty good. Increasing the contrast a bit will bring the blacks and whites in towards the centre a bit.
    "There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).

    Regards
    Bill

  2. #22

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    Can you please give more detail about your workflow (coating method, drying method times, developer, ect. all the details step by step) and working conditions (temperature, humidity)?

    The step tablet print you show us has no pure white and you can see tonal progression up to the 21th step. But you still don't have a full or almost full black.

    Interesting, never encountered such a case:
    - Lack of clear whites but full tonal progression until the last step indicates too much exposure to me. (I think we would agree on that.) If it was chemical fogging we wouldn't see tonal progression, right, only fog.
    - Lack of full back could be due some kind of bleeding, but then why it's only under the negatives? I'm totally puzzled.

    Have you tried other papers to eliminate if that's a paper issue? Also is your FO fresh?

    Regards,
    Loris.

  3. #23

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    Thanks much,Loris.
    The details are as belows:
    temperature:19 degrees, humidity: 68%
    I use a synthetic brush. After coating I let it dry naturally in the dark for twenty minutes.Then go for exposure. The developer is sodium citrate. Citrate acid and EDTA as clearing agent.

    I haven't tried other papers.The FO is not fresh though. I bought it from B&S about 5 months ago. How to judge if it dues to the freshness of FO? Also could it be the problem of UV lights? It's too cloudy these days to have it exposed in the sun.

  4. #24

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    What is the exact model number of your lights? Let's see if there's any spectral power distribution chart for them on-line...

    Definitely try other papers that are known to be working well with pt/pd process. Also old FO can be freshened by adding small amnt. strong hydrogen peroxide (strong to not dilute the iron solution too much), but that's not the business rigth now - we're not sure it's your FO, that (or buying new FO) would be the last measure.

    Regards,
    Loris.

  5. #25

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    BTW I see some grain only in the lower tones, usually sign of bleeding... Check if the print is bleeding during development. If yes try to use tween or similar surfactant to let the paper absorb the emulsion better...

  6. #26

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    Loris, the UV light is HITACHI F30T9 fluorescent lamp.

    May I ask what bleeding means? Sorry for the ignorance :P

    Thanks a lot!

  7. #27

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    Bleeding is where the blacks run (or leak or spread) into the whites.
    Loris, I hesitate to reveal my lack of understanding of things, but do not these results indicate a lack of sufficient contrast. Sudek, at what contrast mixture are you doing these?
    "There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).

    Regards
    Bill

  8. #28

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    Sudek, this is a 36" / 30W lamp with UVA output peaking at 350nm, right? 30W per 36" is a little on the weak side but perfectly useful. My 24" bulbs are 40W for instance, yours should be equivalent to 20W / 24". Not strong, but not weak too. I know people printing with 20W lamps and our exposure times are close to each other.

    Apart staining whites, bleeding is loss of image forming substance from paper, therefore leads to weaker dmax.

    Bill, I know no dop pd mixture that exceeds log 3.0 exposure scale - if there isn't something really wrong with sudek's mixture, that is. That's why I asked about their FO, maybe it's stale.

    sudek, measure FO enough for one print and try to mix 1 drop of OTC peroxide (3%) in it, swirl, wait a little then add the metal and print. See what happens? If things get better, it's stale FO. You should better choose to mix a fresh solution instead of fiddling with peroxide addition; it's hard to control that.

    Regards,
    Loris.

  9. #29
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    Hi Loris,

    Just squeezing some info on bulbs, I am using 24" 20W BL368 (a set of 10 with some diy reflector in the back). Well,my exposure times are quite close to Loris's, differences are mostly from the base densities of different materials.

    Sudek's 40 minutes exposure really sounds strange to me. Yet again I have no experience with DOP pt/pd, but I would not expect such long exposure.

    Regards
    Serdar

  10. #30

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    Cowanw, I use a mixture with equal amount of FO and palladium solution.According to Dick Arentz's book, the appropriate exposure time/distance can be dertermined this way by having two to three black wedges reach maximum black and indistinguishable from each other. I did experiment with decreased distances last night,1.8 inches, for example, and exposed for half an hour.Then I saw bleeding and several numbers got blurred.But still I didn't see any step reaching maximum black. As I'm planning to make palladium prints with digital negatives, I'd like to control the contrast of the negative to match the paper, rather than controlling the contrast of the solution.But I don't know now how to get that basic exposure time. Pity that I don't have NA2 on hand otherwise I'm eager to see what happens if the contrast changes. And how come my contrast obtained with a "normal" mixture of sensitizers are so different from others?

    Loris, thanks much for the kind suggestion. And if the coated paper can reach maximum black in several minutes, may it prove that the FO is not so stale?



 

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