VanDyke Brown formula question, Brown vs Green Amonium FerricCitrate

Discussion in 'Alternative Processes' started by Herzeleid, Oct 30, 2012.

  1. Herzeleid

    Herzeleid Member

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    I noticed that in various formulas both green and brown varieties of AmmoniumFerricCitrate can be used to create the VDB sensitizer.

    How does it effect the tonality, color or does it even effect it?
    Just out of curiosity.
     
  2. MDR

    MDR Member

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    The loss of speed is the main difference haven't noticed all that much difference in tonality. Green is faster than brown.

    Dominik
     
  3. Urmonas

    Urmonas Member

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    The green variant is faster, but I have found the brown to be fresher, at least from the place I buy my supplies (local chemical supplier). You will need to use a little more of the brown for the same behaviour. Sorry I can't recall the ratio from memory. Tonality wise I have not seen any consistent difference.
     
  4. cliveh

    cliveh Subscriber

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    May I please ask what you mean by fresher? We are not buying vegetables here.
     
  5. Herzeleid

    Herzeleid Member

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    What about the precipitate forming in the solution?
    Is brown better or the same? Because if eliminates the silver-iron rust like precipitation in bottle I would like to switch to brown.
     
  6. Loris Medici

    Loris Medici Member

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    Serdar, both variants work. The green form has more Iron(III) compared to the brown form (roughly 19% against 14% - it's not exact science; use this as rule of thumb...), therefore you'll need more (~ 20-30%) of brown form. About the precipitate; just add the silver solution very slowly to the combined A (iron) + B (tartaric acid) solutions, almost drop by drop, while vigorously stirring the solution, also, try to double the amount of tartaric acid if you still have considerable amount of precipitate. (More acid will lead to a slightly higher contrast emulsion, which has less tendency to stain and fog - both qualities are desirable actually...) Let the solution stand a couple of days while occasionally shaking it, then let the solids settle in the bottom and filter it using a coffe filter. The solution will still work well. AND, definitely try gold-thiourea toning with Vandykes - you'll get a much much stronger image (w/o double coating) both in terms of darkness/dmax and longevity.

    Hope this helps,
    Loris.
     
  7. cliveh

    cliveh Subscriber

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    Loris, for once I agree.
     
  8. Herzeleid

    Herzeleid Member

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    Hey Loris,

    I have 2 VBD sensitizers at the moment, one with increased TA (VDB2), the other regular formula. My first VDB solution gone bad :smile:

    The regular one has deeper browns, dmax. Maybe quite close to black if I do double coatings. Blacks are like roasted coffee beans in terms of color.
    I actually quite like the extra TA, may be it is related to the benefits you mentioned, but the dmax is not as impressive as the regular one. Blacks are like chocolaty brown.

    So I prepared the regular VDB quite recently. I added drop by drop, and stirring continuously.
    I still have some precipitate. Well, not much to worry about but it bugs me.
    But may be I should give VDB2 a try, double coat and compare dmax.

    BTW when I filtered the precipitate from my first VDB solution, well it turned horrible, weird stain like things happened on prints. I have no idea why.

    Gold toning is on my list, but I will use untoned VDB and Salt for my project. I am waxing them, it is quite effective actually.

    Thanks
    Serdar
     
  9. Loris Medici

    Loris Medici Member

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    Hi Serdar,

    I was always double coating before I started using gold toner, I didn't bothered afterwards. (I'm sure I could still get a better dmax by double coating, but the blacks I could get with gold toned single coated prints was convincing...) About the horrible results after filtration: That's definitely contamination, what filter paper did you used? I use "Melitta" brand coffe filters, they're completely safe. (So safe that I recently filtered USD 800 worth Pd solution!!!) And definitely use very clean vessels and tools while working with the solution. Strange stain patterns in the print usually indicates problem with the brush, not the solution BTW...

    Regards,
    Loris.
     
  10. Herzeleid

    Herzeleid Member

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    Hi Loris,

    You are definitely right, it must be contamination. I never thought of that. I don't remember what I used to filter the solution :smile:
    I will try double coating soon.

    thanks