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  1. #11
    Ian Grant's Avatar
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    Suprol - Reversal processing

    Nick, there is or rather was a very informative technical data sheet for May & Baker Suprol. May & Baker became Champion.

    The data sheet was published in the 1970's and gave a lot of extremely useful and detailed information on a wide range of uses for Suprol, and this included reversal processing and adjustments to obtain different gammas etc.

    Other uses were as a fine grain developer for commercial processing, and at about 1+29 or higher dilution for tank development, and it did give very fine grained negative.

    Suprol is fairly similar, effectively equivalent, to Ifords PQ Universal and so would give you pointers for adjusting and using a developer like ID-62, or even ID-72

    My copy of the datasheet is in storage but if you can't find a copy I'll try and dig it out next time I'm in the UK.

    Ian

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    Sodium Carbonate Vs Poassium Carbonate

    Reviving this thread with a related question....

    I noticed the recipe attached to this thread includes a "Agfa 80" recipe. The main difference between the D-19 and Agfa 80 is that Potassium Carbonate replaces Sodium Carbonate in the Agfa 80.
    I was just wondering what the effect of this may be?

    I'm asking as I was about to mix my own D-19 when I realised I was low on Sodium Carbonate but had plenty of Potassium Carbonate.

    Regards,
    Peter

  3. #13
    mts
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    D-19 is the old standby for astronomical imagery primarily due to its high straight-line gamma and short toe (low fog level). It was used with plates from about the early part of the last century up through the 80s when CCD detectors came into wide use. I used it with the standard glass-plate emulsions for astrophotography forty years ago, 103a and the like. It was also used for spectroscopy and for "patrol" cameras that were used primarily to record and discover asteroids.

    For consistency you should always measure and set the developer pH to the level (around 10 to 11) that gives you the result you want.
    By denying the facts, any paradox can be sustained--Galileo

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    You can replace sodium carbonate with potassium carbonate if you correct for the difference in molecular weight. Potassium salts are slightly more active then their sodium analogs in photograpic formulas. The one exception being for use in fixers where the potassium salts retard the fixing process.
    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

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    Thanks for clarifying that.

    Regards,
    Peter

  6. #16
    Ian Grant's Avatar
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    Quote Originally Posted by HumbleP View Post
    I noticed the recipe attached to this thread includes a "Agfa 80" recipe. The main difference between the D-19 and Agfa 80 is that Potassium Carbonate replaces Sodium Carbonate in the Agfa 80.
    I was just wondering what the effect of this may be?

    Peter
    Agfa (Orwo) tended to use Potassium Carbonate (& sometimes sulphite) because of the higher solubility compared to Sodium Carbonate (& sulphite), this allows storage of more concentrated solutions.

    In commercial liquid concentrates they go a step further and use a smaller amount of Carbonate and a little Hydroxide to achieve the same pH, Ilford & Kodak do the same. This is quite useful when making up your own concentrated stock solutions.

    Ian

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    Quote Originally Posted by Gerald C Koch View Post
    You can replace sodium carbonate with potassium carbonate if you correct for the difference in molecular weight. Potassium salts are slightly more active then their sodium analogs in photograpic formulas. The one exception being for use in fixers where the potassium salts retard the fixing process.
    Isn't the carbonate part only that is active? That is, pH is controlled only by cabonate, not the counter-cation.
    I did know K+ salts are only a little soluble than Na+ salts. Maybe is this the difference?

  8. #18
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    In a developer Potassium salts will give marginally finer grain than Sodium, this is most noticable with warm tone developers where it's the fineness of the grain that alters the warmth.

    The differance in solubility between Sodium Carbonate 215 g/L (20 °C) and Potassium Carbonate 112 g/100 mL (20 °C) is quite marked, hence why Potassium Carbonate is used in commercial liquid developers.

    Ian

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    Quote Originally Posted by Ian Grant View Post
    In a developer Potassium salts will give marginally finer grain than Sodium, this is most noticable with warm tone developers where it's the fineness of the grain that alters the warmth.

    The differance in solubility between Sodium Carbonate 215 g/L (20 °C) and Potassium Carbonate 112 g/100 mL (20 °C) is quite marked, hence why Potassium Carbonate is used in commercial liquid developers.

    Ian
    Did you mix these two up?

  10. #20

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    Quote Originally Posted by Alessandro Serrao View Post
    Isn't the carbonate part only that is active? That is, pH is controlled only by cabonate, not the counter-cation.
    I did know K+ salts are only a little soluble than Na+ salts. Maybe is this the difference?
    At the strengths usually employed in photo graphic developers the hydrolysis of potassium carbonate (separation into caustic potash and bicarbonate) liberates a much greater amount of caustic alkali than does the hydrolysis of sodium carbonate, so that potassium carbonate gives developing solutions of greater energy.
    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

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