Electrolytic development

Discussion in 'Black and White' started by ianrivlin, May 14, 2016.

  1. Do any members have any experience with electrolytic physical development? I can't see any reason
    why an electric current passed across a film emulsion wouldn't reduce the silver, just as chemical
    reagents do. I could see this offering benefits too ie, no silver grain clumping, developing cost would
    be virtually zero and simply altering the current would adjust the density. I envisage a current passing
    across the width of the film, whilst the film is in an electrolyte (saline or sodium sulphite). The current
    would be supplied by slowly revolving metal rollers touching medial to the perforations, each side. The
    mechanism would be very simple and "development" time might be acceptably short. If anyone wants
    to collaborate on such a project, please get back to me. Ian
     
  2. Not that odd. I read once about Kodak doing this as an experiment Also some about using a silver or gold wash. Not sure if I can add more other than it was not a short process.
     
  3. I fail to see how moving electrons can absorb silver particles to reduce it. The chemicals that are used to reduce also contain the absorbed silver and are flushed away. Relying on an electronic field could only change chemical bonds; Change yes, reduce no.
    I suspect if you seriously perused this experiment you would discover all kinds of useful effects, except the one you are looking for.
     
  4. >>I fail to see how moving electrons can absorb silver particles to reduce it.

    Nope, nothing to do with absorbing silver particles. Reduction just means you're tacking on one or more electrons, in this case to a silver cation, to make it into reduced metallic silver. Photo developers (like ascorbic acid and so on) are gentle reducing agents.

    To me it sounds like an interesting idea, but it might be hard to control in comparison with wet chemical development, which as we all know can be infinitely fine-tuned. I think if you were to suspend your exposed film in a bath of saline, the current might just short-circuit through the liquid and bypass the film. Good for chrome-plating car bumpers, maybe not so good for developing film.
     
  5. With appropriate ions in solution, they will be reduced and oxidized at the cathode and anode, respectively. Usually the easiest ion to reduce or oxidize at the appropriate electrode will be the one, though it also depends on the concentration.
    Otherwise, for most developers, sulfite reduces the oxidized form of the developing agent, and the developing agent reduces silver ions.
    If you run a current through a solution with, for example, hydroquinone and its oxidized form, some would be reduced at the cathode and some oxidized at the anode. If one electrode was close to the film, that form might be more ready to react with silver ions.
     
  6. I seem to remember (it was
    decades ago) an article
    describing this process. Whether
    it was a theoretical or actual
    process, I can't remember. I also
    can't remember if it was using
    film or some other base (ie
    electrically conductive...).
    Imagine a base made of gelatin or an electrically conducting gel
    which is infused with sensitised
    silver nitrate. An
    electrode on either side of this
    Gel - with a DC current
    flowing - would "add"
    electrons, ie,reduce the intervening
    material, surely?
     

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