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  1. #1
    Athiril's Avatar
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    Ascorbic Acid to dissolve silver off film..

    Okay so I made up a strong solution of ascorbic acid with pleny of sodium hydroxide, much stronger in each case then one would use for development, gathering up so of my many failed processing attempts and dumping them in the jar the silver developers and eventually is removed from the film.

    Until I'm left with clear acetate/base, a very dark grey opaque solution.

    Running it through a paper filter, barely any of the solution gets caught in the filter, so it is dissolved.

    Im assuming if I evaporated the solution and use enough methylated spirits to redissolve the ascorbic acid, I can filter that off to remove the ascorbic acid, then redissolve in water, in which the silver shouldnt be able to dissolve without the ascorbic acid.. at least I think.


    What form is the silver in the solution?


    I want to experiment with this until I get my next order of chemicals in which will include bromide and nitric acid.


    putting a little does clear a dark potassium permanganate solution clearer, and sort of a yellow dull colour, so im guessing its still metallic silver.. back to halides in the permanganate... i wonder if this can be of use to me
    Last edited by Athiril; 10-28-2009 at 08:05 AM. Click to view previous post history.

  2. #2
    Photo Engineer's Avatar
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    Sodium Hydroxide alone will remove the coated layer from film.

    It will also remove the subbing in most cases, thereby rendering the film uncoatable in the future. It depends on the subbing.

    PE

  3. #3
    Athiril's Avatar
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    Ah I was going to ask about recycling the film base... so much to learn..

    Guess I cant do much until I get the rest of the stuff I need.


    Edit:

    Im getting a precipitation from a small amount of solution (0.5ml) in a copper sulphate solution... also in magnesium sulphate solution (epsom salts).
    Last edited by Athiril; 10-28-2009 at 09:57 AM. Click to view previous post history.

  4. #4

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    Is an NaOH / Ascorbic acid solution what is normally used to remove exposed silver from a negative in order to make a positive (i.e. the exposed negative is clearedof all silver, the remaining unexposed halides exposed to light and redeveloped to form a positive?)

    I was considering shooting paper negatives and processing them directly into positives, but couldn't find the process.

  5. #5
    Photo Engineer's Avatar
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    The Sodium Hydroxide alone will remove all emulsion and silver from a negative and may remove all or some of some types of subbing. It has nothing to do with making positive or negative images. And, it is a rather poor way of removing the coating. Much like using a nuclear weapon to kill gnats! Over kill!

    Basically (pun intended) the NaOH causes complete decomposition of gelatin which then dissolves into the solution as a mix of the salts of the various amino acids making up the gelatin.

    PE

  6. #6

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    This all sounds like a way to make a big mess...

    Is the point of this to recover silver metal or just to have some fun? Or perhaps both?
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  7. #7
    tiberiustibz's Avatar
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    It's used to clean drains. The fact that it removes emulsion from film is secondary

  8. #8

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    Ascorbic Acid for drains??
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  9. #9
    Photo Engineer's Avatar
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    NaOH is for drains and for removing emulsion from film, paper and plates. Ascorbic acid is riding along doing nothing much AFAIK. NaOH can remove skin from bones and dissolve clothes as well.

    PE

  10. #10

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    Quote Originally Posted by Photo Engineer View Post
    NaOH is for drains and for removing emulsion from film, paper and plates. Ascorbic acid is riding along doing nothing much AFAIK. NaOH can remove skin from bones and dissolve clothes as well.

    PE
    So what is the stuff that mobsters use for dissolving skin, bone and all? I gather NaOH won't do that?

    I recall seeing a scene on the Sopranos where they chopped up a body into parts and then placed the parts in the stew that apparently reduced them to nothing.

    Sandy

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