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  1. #11
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    Jordan;

    I'm somewhat aware of this process but had pretty much dismissed it, if you will pardon the expression. You see, the silver halide solvent in a separate bath can also IMHO, bleach out the detail in both highlights and shadows if you miss the sweet spot even slightly, and the lack of solvent in the developer profoundly affects grain and sharpness that you would otherwise be entitled to.

    I was not aware that this is what was meant, and did not know that it was still in use due to the difficulty of hitting the sweet spot on a long roll of film. It probably works best with sheet films done one at a time.

    If you can get it to work, more power to you, but I would not recommend it myself.

    Sorry for the misunderstanding.

    PE

  2. #12

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    PE,

    I agree that there is necessarily a sweet spot and that it's easy to miss. (B&W reversal is all about sweet spots, which is why I don't play around with it as much as I used to.) I first encountered this method in a forum post about two years ago, where the poster appears to have stumbled on the idea himself. Is there some earlier patent or scholarly literature on this approach?

  3. #13
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    I would have to review my library and Haist in particular. IDK. I know that Grant and I talked about this and other items like this. I also worked in the same office as some of the E6 team and heard their comments. I also am 'heir' to one of the rare chemicals used in the first developer for use as a silver halide solvent. I am trying to get a reasonable source for the Formulary to sell, but this chemical is VERY expensive. It gives a super boost to B&W reversal processes but Kodak will only sell it in $25,000 drums.

    PE

  4. #14

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    PE, I agree with you about the difficulty of hitting the sweet spot, especially on a whole roll at once. That has been a real part of the frustration with this process. How does integrating the silver solvent into the developer make the process less tricky? Does the developer moderate the silver solvent or have some kind of compensating effect?

  5. #15
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    The silver solvent in the developer makes it more like a self limiting situation.

    PE

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    That is good news. Can you elucidate the mechanism of this for my chemistry-oriented brain? Thanks ;-)

  7. #17
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    Well, two or more things go on when silver halide solvents are in the developer. The first thing is that with proper formulation fog goes up which in a sense is increasing the development until all silver is used up and this clears the highlights in the reversed image.

    The second thing is that the silver ion concentration in the developer goes up and it can be reprecipitated at other points increasing image density and contrast.

    The silver ion has to come from somewhere, and this is done by dissolving crystals making grain finer.

    This is all done at the expense of sharpness as it dissolves some finer grains and also can mute the edge effects. This is visually offset by the increased contrast. It is also the source of the other reference to fine grain is achieved at the expense of sharpness. The reversal process is an intermediate position that appears to contradict this statement as it does improve grain, but sharpness appears better due to the high contrast of the visual image.

    Microdol X is an example of a fine grain developer that uses a silver halide solvent.

    PE

  8. #18

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    PE, interesting to think of fog being a way to clear highlights (by consuming unexposed AgX). Most reversal first-developers are D19-based (plus thiocyanate) and I don't think of this as a "foggy" developer. Or is it?

  9. #19
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    Actually, the developer may or may not be "foggy". The intent is to force all silver to develop in negative Dmax areas, even so called "dead grains". If any are left, then they surely develop after reexposure and second development. So, a forceful developer with silver halide solvent is often foggy when used as a reversal first developer. The fogging action is a byproduct of its intense activity.

    If you look at E6 film after first development, the film is visually foggy. This is due to the fact that the first developer is "foggy" with a silver halide solvent and high activity, and also the fact that the emulsions are relatively over sensitized with sulfur + gold to give high speed and this leads to a bit of fog. They don't care about the negative fog, as it vanishes in the reversal process and it helps clean out the dmin by leading to full development of all negative grains in negatie dmax areas.

    OTOH, I look at silver halide solvents as being natural fogging agents. Ammonia in a developer can cause strong fog, thiourea is a fogging agent and etc... Used properly they can yield a monobath or Microdol X and improper use can lead to dichroic fog or overall ordinary fog.

    PE

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