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  1. #21
    Ole
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    A strange side effect of fixer in the developer is that sometimes the development is faster with fixer in! I believe it is a result of the fixer dissolving the siver halide crystals, so that the developer has better access to fresh sites to work on - but i might be wrong. Anyway, it's probably related to the development of van Dyke prints in the fixer...

    With a very rapid developer, diffusion speed is the limiting factor on how short the development can be. And fixer might actually help it a bit here, if my guesstimate of what goes on is within a reasonable margin of being a usable model.

    PS: That last sentence could only have been written by a geologist trying to avoid committment!
    -- Ole Tjugen, Luddite Elitist
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  2. #22
    Donald Qualls's Avatar
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    One other factor to keep in mind for monobaths -- if your developer and fixer have the same working time, you'll lose shadows because the halide will fix away before details are developed there. OTOH, if the developer goes to completion, with most developers, you'll have excessive contrast. In your case, the Superfixer might be overkill even with RUD (though if you could package the two together in gel form, you're on the road to making your own Polaroids -- think in terms of 70 mm film used to create reloads for old roll-film Polaroid cameras like the Pathfinder 110).

    And yes, it's necessary to alter the proportions and/or alkalinity both to control contrast, and to accommodate different films (fixing rate and developing rate don't maintain the same relationship with different emulsions). The simple way to do this would be to carry two or three bottles of concentrate -- one RUD, one Superfixer, one of something like sodium carbonate or even sodium hydroxide solution for adding alkalinity when needed -- and mix the stuff as needed. No more complicated than making salad dressing -- for a 35 mm roll of Film Q, use X ml RUD concentrate, Y ml Superfixer concentrate, Z ml carbonate solution, and water to make 240 ml. Mix, pour into tank, agitate for two minutes, and wash. Washing will be fast too, of course, because the film is left alkaline.

    Bad news is, liquids are frowned upon for air travel, and unidentified white powders in your luggage aren't much better... :P
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

  3. #23
    Donald Qualls's Avatar
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    Quote Originally Posted by jdef
    Regarding the limiting factor of diffusion speed, I've seen descriptions of development processes that develop film in fractions of a second at high temps with special equipment.
    And in a slightly less exotic arena, some B&W Polaroid systems develop/fix in 15 seconds at "room temperature" of around 70 F (though the Type 55/665/85 P/N family take a minute or more)
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

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