Citrazinic acid in E6 color developer - purpose? subs?

Discussion in 'Color: Film, Paper, and Chemistry' started by cinejerk, Feb 20, 2012.

  1. cinejerk

    cinejerk Member

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    This reagent is in all the E6 color developer formulae that I have. What is it's purpose? Is there any substitute?
    Very difficult to locate.
    thanks
     
  2. stefan4u

    stefan4u Member

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    Citracinic acid reacts as competitive colourless coupler in the higher Densities of the slide in order to reduce the D max. or control the Contrast. This means if you take more Citracinic acid the contrast will decrease, this can be a benefit for reproductions.

    If you want to start homebrewing this ingredient can be skipped eventually, if otherwise the option is to toss the whole project…In my Chromebrews I reduced it’s amount about 50% to 0.6g / Litre. for increasing the contrast a bit. That worked fine for me, but to be honest I’ve never thought about substitutes (it will be tricky because of the nonlinear effect)

    Maybe sulphite, but this will effect more or less all densities, not only the higher ones, or more silver soluble agent but this will pronounce a loss more in the lower densities...

    Regards,
    Stefan
     
    Last edited by a moderator: Feb 20, 2012
  3. Mike Wilde

    Mike Wilde Member

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    I think it gobbles up loose coupler components, but I cannot recall where I heard this.

    It seems to be related to contrast control, in my dim memory.

    The analog in b&w might be what bromide does, a sort of restrainer, but for color couplers.

    I think the opposite effect is had with one that Rowland called H-acid.

    Some day I will spring for a copy of Haist, and then I perhaps will have a reference to look to for this type of question.
     
  4. Mike Wilde

    Mike Wilde Member

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    I bought a small supply from Claire at JD Photochem before she packed up shop. Some day I dream of tracking down what she did with her remaining stock.
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    Stefan has it correct. Substitutes are "H Acid" and "J Acid". I have no idea of the substitution ratios, nor if they are exactly identical. Citrazinic acid also controls grain as well as contrast. It can have some effects on sharpness as well.

    PE
     
  6. cinejerk

    cinejerk Member

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    Ok then it sound pretty important.

    Then I guess I need a source.

    Or is this just more unobtainium?

    I have talked to a lot of chemical vendors and they have never
    heard of it ????
     
    Last edited by a moderator: Feb 21, 2012
  7. Rudeofus

    Rudeofus Subscriber

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    Sigma Aldrich claims to have some left.
     
  8. cinejerk

    cinejerk Member

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    Thanks Rudeofus
    Ouch $75 for 100g
    Yea I know, now I complain about price. :laugh:
     
  9. Rudeofus

    Rudeofus Subscriber

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    It may give you some comfort that I was shown the price 110€ for 100g :confused:

    Given the trace amounts of citrazinic acid needed in published recipes the price seems bearable, though, even the European rip off price.
     
  10. A_Caver

    A_Caver Member

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  11. cinejerk

    cinejerk Member

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    Oh really !!! A_Caver how much did they charge you for what quantity? thanks
     
  12. A_Caver

    A_Caver Member

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    I purchased 100g for $58.00 last year. It came as 2 x 50g bottles.