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  1. #1
    SMBooth's Avatar
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    Hydrquinone Vs Phenidone mixing mistake

    I just mistakenly used Hydrquinone instead of Phenidone when mixing some 510 pyro. Out of interest I developed a FP4+ at 1:100 to see what would result. To my delight the negative come out really nice.
    What is the difference between the two?

  2. #2

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    If you mixed 1g of Hydroquinone in place of 1g on Phenidone I don't thing that amount of Hydroquinone would have much if any affect at all. Of course, I could be wrong on that one. JohnW

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    SMBooth's Avatar
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    Well it was 5 gram into 10gram of pyro.

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    How they behave is of course dependent on the rest of the formula (other developing agents, pH etc), but they are not the same type of developing agent at all. Generally speaking, Phenidone is a low contrast but highly active agent at relatively low pH values, giving good speed . Hydroquinone is typically used as a high contrast agent, but typically needs to be present in higher concentrations and needs a higher pH to function as a primary developing agent. Its function in general purpose, moderate pH, fine grain film developers is usually as a "secondary" agent to regenerate Phenidone or Metol.

    510 Pyro is supposed to be mixed with 0.25g Phenidone. 0.25g is a very small amount for Hydroquinone, so I don't know what it is or is not contributing in terms of image formation in this otherwise Ascorbic Acid-Pyro developer. My assumption is that without the Phenidone you'd at least have a speed loss vs the proper formula.

  5. #5
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    Sorry it was only .25 gram not the 5 grams (that was Ascorbic Acid) So practically little , if any effect.

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    Hello,
    Phenidone is commonly used as a replacement for metol. Since it is more active than metol only 1/9 to 1/8 of the metol amount is necessary. Since Phenidone does not answer to bromide as well as metol, usually benzotriazole is necessary as antifog.



 

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