Base level fog and Tri-X Reversal question (where is it?)

Discussion in 'B&W: Film, Paper, Chemistry' started by mr.datsun, Feb 18, 2013.

  1. mr.datsun

    mr.datsun Subscriber

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    NB. I'm starting a new thread on this as my old thread on the general subject had become unwieldy and too digressive. And so this thread aims to be based around one question.

    Context:
    I'm dev'ing 35mm Tri-X reversal in order to practice before moving on to the more expensive Super 8 Tri-X Reversal. I'm using Dektol liquid (i.e. Polymax).

    At the moment I am only trying to find the maximum dev time until base-level fog is reached. As some of you will already know this is meant to be important to get clear hilights when reversal processing.

    This test should also tell us how long the developer takes to build maximum silver content on the film before any EI tests are done.

    I am using the Dektol paper developer for it's energetic nature, as is required in reversal processing (check the literature). It has been used for reversal processing very successfully with a lot of other films - e.g. by Mr. Red.

    I do not have densitometers so am trying to do this the simple way.

    Process:
    I am using Dektol liquid at 1+5. This is the equivalent of Dektol powder stock at 1 + 1. (ie. - strong.)

    I am testing on unexposed Tri-X 35mm.

    5 mins . No fog.
    10 mins. No fog.
    15 mins. No fog.
    20 mins. No Fog.

    NB: I do get black on the exposed part of the test strip and the edge lettering.

    Question:

    Why am I not seeing fog?

    I have had the same results with PQ Universal where I can get a usable image at a reasonable 10m but cannot get fog at 16m.

    I'm convinced that I'd get a fully developed image by 5 mins with Dektol. This method of getting base fog and hence finding ideal max dev time sounds great in theory does not seem to be working (at least with Tri-X for me).

    Is there another way of getting the dev time near correct before doing EI tests, please?
     
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  2. mr.datsun

    mr.datsun Subscriber

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    ssuper 8 tests.jpg

    [20m, 10m]
    [15m, 5m]

    5m looks a little yellow in the middle. I didn't fix it long enough, I think and rectified in the others.
     
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  3. Rudeofus

    Rudeofus Subscriber

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    The task will be a bit harder than that because final density is the silver that you neither developed nor dissolved away (with the solvent in your FD). Because of that solvent you can't really say x density after FD means y density in the final image.

    BTW your attachment link does not work for me.
     
  4. mr.datsun

    mr.datsun Subscriber

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    I understand what you are saying but the theory is that you want the maximum silver in your image but also that a little fogging also helps to clear hilights (because it then gets cleared in the bleach). Rather than worry about the final image and the slightly unknown precise relationship between the first image and it, I'd like to find the point at which the 1st developer has done it's maximum work before causing fogging. This should be knowable irrespective of EI. At least then I would have a 1st development time baseline to start from.
     
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  5. mr.datsun

    mr.datsun Subscriber

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    Just as an update and to close off this thread. I have now run the following development tests:

    0m, 1m, 5m, 7m, 10m up to 40m at an equivalent of 1+2 dektol or 1+9, Polymax (liquid Dektol).

    The fogging is much much less pronounced than I expected but I can just about see that it creeps in between 5m and 10m. Also I can identify maximum black achieved between 7m and 10m on the exposed end of the test sample.

    So. I estimate 8m in Dektol Liquid at 1+9 for Tri-X for maximum development. Independent of EI. This is what I will work with at the EI stage of testing.