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  1. #1

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    A fortified TCB developer for long shelf-life

    Developers containing ascorbic acid as antioxidant may well have long shelf-life, but when used similar to D76, they loose their power rather quickly due to oxydation of the ascorbic acid from the air introduced into the developer when used.

    The solution to this may be my version of the TCB-developer.

    More information and picture at A TCB developer with long life.

  2. #2

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    I don't understand your post. First you talk about developers using ascorbic acid as an antioxidant. Then you state that such developers loose their power rather quickly. The lose of "power" would be due to lose of developing agent due to oxidation not to lose of antioxidant. The pH of the TCB developer is >9 and at this pH the ascorbate ion is an active developing agent. If by "used similar to D-76" you mean replenishment then Kodak states that Xtol (an ascorbate developer) will keep indefinitely as long as it is replenished regularly.

    Since TCB contains no chelating agent to prevent Fenton oxidation its keeping properties will be poor as compared to Xtol and other formulas that do use a chelating agent.
    Last edited by Gerald C Koch; 12-01-2011 at 11:46 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  3. #3

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    Quote Originally Posted by Tronds View Post
    Developers containing ascorbic acid as antioxidant may well have long shelf-life, but when used similar to D76, they loose their power rather quickly due to oxydation of the ascorbic acid from the air introduced into the developer when used.
    The solution to this may be my version of the TCB-developer.
    More information and picture at A TCB developer with long life.
    Thank you for posting this interesting formula, which I copied below:

    500 ml water.
    8 g Sodium carbonate. (Soda)
    10 g Ascorbic acid. pH at this moment is 9.6
    80 g Sodium sulfite
    10 ml Parodinal
    20 g borax.
    Water to 1000 ml. pH at this moment is 9.15
    I have one question: Why does the formula have both Sodium carbonate and Borax? By adding more carbonate, you can omit the Borax. Does the Borax improve the image quality?

    Cheers,

    Mark Overton

  4. #4

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    Quote Originally Posted by Gerald C Koch View Post
    I don't understand your post. First you talk about developers using ascorbic acid as an antioxidant. Then you state that such developers loose their power rather quickly. The lose of "power" would be due to lose of developing agent due to oxidation not to lose of antioxidant. The pH of the TCB developer is >9 and at this pH the ascorbate ion is an active developing agent. If by "used similar to D-76" you mean replenishment then Kodak states that Xtol (an ascorbate developer) will keep indefinitely as long as it is replenished regularly.

    Since TCB contains no chelating agent to prevent Fenton oxidation its keeping properties will be poor as compared to Xtol and other formulas that do use a chelating agent.
    Well, Go head and do a test run if you don't understand this.

    The ascorbic acid is converted to ascorbate.
    When using ascorbic acid both as an antioxydant and a developer agent, it works well until you start using and reusing the developer. It will be oxydated by aerial oxydation.
    When enough of the ascrobate is oxydated, it will loose it's powers. Since phenidone forms a superadditive pair with ascorbate, the loss of ascorbate will kill the developer.
    This has been tested and I know for sure it will stop working after very short time.

    By using it as D76 I mean using it as D76, not as XTOL.
    Replenishment is another issue. If this developer is replenisshed, it will keep forever.

  5. #5

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    Quote Originally Posted by albada View Post
    Thank you for posting this interesting formula, which I copied below:

    500 ml water.
    8 g Sodium carbonate. (Soda)
    10 g Ascorbic acid. pH at this moment is 9.6
    80 g Sodium sulfite
    10 ml Parodinal
    20 g borax.
    Water to 1000 ml. pH at this moment is 9.15
    I have one question: Why does the formula have both Sodium carbonate and Borax? By adding more carbonate, you can omit the Borax. Does the Borax improve the image quality?

    Cheers,

    Mark Overton
    The reason for using sodium carbonate is that you have to convert ascorbic acid to ascorbate. The pH required for this conversion is above the pH of borax.
    This is done when adding the ingredients in the listed order.

    Adding more carbonate will make the developer more active, but you will get more grain.
    Keeping pH as low as possible helps keeping the fine grain properties of ascorbic developers. The pH must be over 9.0, so using borax as buffer is great since the pH will be in the range 9.1 - 9.2.
    The parodinal amount is 1:100 in this developer and not enough to develop a film in 10 minutes alone, so the ascorbate is doing a great job.
    The p-aminophenol in the parodinal does help the shapness. This is a well known property of the Rodinal developer. Combining fine grain and sharpness isn't easy, but this developer does this.

  6. #6

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    Your brew contains more ascorbate and sulfite than some Xtol-Rodinal mixes that have been tried,but probably has similar development chemistry.For example:

    Xtol(1+0).........200ml
    Rodinal...............6ml
    Water to..........600ml
    http://www.apug.org/forums/forum37/5...cutance-6.html

    It does not appear to be known for sure if the increase in sharpness over Xtol (1+2) is the result of increased pH or some chemical effect of p-aminophenol.

  7. #7

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    Quote Originally Posted by Tronds View Post
    The p-aminophenol in the parodinal does help the shapness. This is a well known property of the Rodinal developer. Combining fine grain and sharpness isn't easy, but this developer does this.
    I would like to see data supporting this. Rodinal is a little sharper than XTOL (and Rodinal's sharpness is generally overstated) because it is a non-solvent developer, not because of its developing agent. Second, combining high sharpness and fine grain is not really possible, unless you develop to a low contrast index, which works quite well with XTOL 1+3 incidentally. I think formulating a developer with a better combination of sharpness and graininess than XTOL would be pretty difficult.

  8. #8

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    Quote Originally Posted by Michael R 1974 View Post
    I would like to see data supporting this. Rodinal is a little sharper than XTOL (and Rodinal's sharpness is generally overstated) because it is a non-solvent developer, not because of its developing agent. Second, combining high sharpness and fine grain is not really possible, unless you develop to a low contrast index, which works quite well with XTOL 1+3 incidentally. I think formulating a developer with a better combination of sharpness and graininess than XTOL would be pretty difficult.
    You don't have to try this if you don't want to. It's your call.
    Besides that, I never ment this to be another XTOL clone.

    To me it is about enough that it gives fine grain and good sharpness in a developer that gives predictable results and is easy to mix and has low cost.

    Try it if you want. If you don't want to try it, I don't care. It's your problem.

  9. #9

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    Quote Originally Posted by Alan Johnson View Post
    Your brew contains more ascorbate and sulfite than some Xtol-Rodinal mixes that have been tried,but probably has similar development chemistry.For example:

    Xtol(1+0).........200ml
    Rodinal...............6ml
    Water to..........600ml
    http://www.apug.org/forums/forum37/5...cutance-6.html

    It does not appear to be known for sure if the increase in sharpness over Xtol (1+2) is the result of increased pH or some chemical effect of p-aminophenol.
    In the testing process I have tried several different mixes with and without the rodinal addition. PCB, PCS, combinations of them etc.
    The TCB version IS sharper. p-aminophenol is known to develop sharp images, so in my opinion it is the key element here.

    I may be wrong about this, but do some tests and decide for yourself.

  10. #10

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    Quote Originally Posted by Tronds View Post
    p-aminophenol is known to develop sharp images
    Actually metol is the preferred agent for this purpose. Metol and phenidone (in FX-39) both come above p-aminophenol (Rodinal) in the tables given on p55 of the Film Developing Cookbook.

    I don't think others will work to verify your claims if you present no evidence.
    Did you compare sharpness with and without p-aminophenol at the same pH?

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