Electrolytic development

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

<p>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.</p>

<p>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.</p>

<p>I suspect if you seriously perused this experiment you would discover all kinds of useful effects, except the one you are looking for. </p>

<p>>>I fail to see how moving electrons can absorb silver particles to reduce it. <br>

<br>

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.<br>

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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. </p>

<p>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. </p>

<p>Otherwise, for most developers, sulfite reduces the oxidized form of the developing agent, and the developing agent reduces silver ions. </p>

<p>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.</p>

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?