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  1. #11
    Ian Grant's Avatar
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    Agfa published 4 different re-halogenating bleaches for toning along with 4 toners, these could be used in any combination to give a wide variety of tones.

    You might try adding 20 gms of Sodium Carbonate or 10ml of Ammonia to a Frerricyanide/Potassium Bromide bleach or a Ferricyanide/Sodium Chloride bleach as both will give different tones.

    Ian

  2. #12

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    Quote Originally Posted by Photo Engineer View Post
    I would think that that bleach would cause loss of highlight detail, due to the formation of AgCl and then the reverse reaction with the formation of AgNO3. This type of rehal bleach was abandoned due to that type of problem.
    Perhaps hydrochloric would be a good substitute - it will make the solution acidic, and add more chloride ions and not nitrate ions so there would be no conversion to silver nitrate.

    I've read that the yellow compound formed when you get nitric on your skin is related to picric acid.
    Kirk

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  3. #13
    keithwms's Avatar
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    That's an excellent suggestion from Kirk. I also imagine that there'd be less issue of aging with hydrochloric- it'd store better than the nitric.
    "Only dead fish follow the stream"

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  4. #14
    Photo Engineer's Avatar
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    Kirk has a good suggestion for adding acid and for preventing solution of the detail.

    IDK what the yellow is, but I have seen it too. Too many times! But, it peels off.

    PE

  5. #15
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    Hydrochloric acid is about as inconvenient as nitric acid for home users, remember that HCl is a gas which tends to escape from the water it is dissolved in, and a bottle of strong acid doesn't blend well with the average house hold. There is no nitric acid equivalent to bisulfate, but if the action of the nitrate ion is not needed, sodium bisulfate would be the most convenient chemical to lower the pH value of your bleach. IIRC, it is a solid used in large quantities to lower the pH of swimming pools, so it should be readily available.
    Trying to be the best of whatever I am, even if what I am is no good.

  6. #16
    Ian Grant's Avatar
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    Quote Originally Posted by Kirk Keyes View Post
    Perhaps hydrochloric would be a good substitute - it will make the solution acidic, and add more chloride ions and not nitrate ions so there would be no conversion to silver nitrate.

    I've read that the yellow compound formed when you get nitric on your skin is related to picric acid.
    The Nitric acid is there to control the size of the grain, the finer the grain the warmer the tone, so in that respect Hydrochloric acid isn't a substitute. Ammonia will also control the grain size which is why Agfa use it in Agfa 502 Bleach.

    Another possibility is to use Ammonium Chloride instead of Sodium Chloride in the bleach.

    Ian

  7. #17
    Rudeofus's Avatar
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    Quote Originally Posted by Ian Grant View Post
    The Nitric acid is there to control the size of the grain
    Would it really do that if such an overabundance of chloride is around? And if it really did, wouldn't bisulfate do the same thing? AFAIK, b&w reversal bleach uses bisulfate plus an oxidizer for this reason.
    Trying to be the best of whatever I am, even if what I am is no good.

  8. #18
    Ian Grant's Avatar
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    Quote Originally Posted by Rudeofus View Post
    Would it really do that if such an overabundance of chloride is around? And if it really did, wouldn't bisulfate do the same thing? AFAIK, b&w reversal bleach uses bisulfate plus an oxidizer for this reason.
    Well if you leave it out the tones aren't the same so it must play a part in the re-halogenation process. If the nitric acid dissolves some silver it would then be converted to Silver Chloride but effectively giving finer grain.

    Ian

  9. #19
    Photo Engineer's Avatar
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    Bisulfate in this bleach can cause problems. You see, it forms Sulfate and Silver Sulfate can then form during the bleach. It turns out that Silver Sulfate is also quite soluble and therefore can remove some Silver image permanently.

    PE

  10. #20
    Rudeofus's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Bisulfate in this bleach can cause problems. You see, it forms Sulfate and Silver Sulfate can then form during the bleach. It turns out that Silver Sulfate is also quite soluble and therefore can remove some Silver image permanently.
    And in this fact it is very similar to nitric acid, that's exactly why I suggested it as replacement. You seem to prove my point here. Compared to nitric acid, bisulfite is a much nicer substance to store outside of a lab environment, too, and you can buy it without getting the strange "what is he going to blow up with this?" look.

    @Ian: Note that the difference between 6B-3 and the other two bleaches is not only the nitric acid but also the halide used for rehal.
    Trying to be the best of whatever I am, even if what I am is no good.

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