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  1. #1

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    Acidification of Fabriano Artistico for Pt/Pd

    Hi,
    I have found, from my little Pt/Pd printing experience, that Fabriano Artistico Natural White HP is my favorite paper for texture, tone, image quality and price.

    Still I have some problems with it - some times, the emulsion is grainy and too light, as if it came off by tiny chunks. I noticed this happens more when I coat with a Hake brush than when I use a synthetic wash.

    Could this be due to poor acidification?
    Dick Arentz suggests soaking the paper in a 1 to 2% solution for 3 min. In this forum, though, I read someone mentioning that they soak it in a 5% solution for 10 minutes. Won't this destroy the paper sizing?

    What I usually do is use a liter of solution and soak about 10 30x40cm sheets, putting them in one by one, rotating them from bottom to top and taking them out in the sequence I put them in - to ensure the soaking is as uniform as possible. I then discard the acid or use it to clear test strips.

    One more thing - after soaking the paper in the acid, I should NOT soak it in water - right?

    Thank you!
    gm

  2. #2
    Don12x20's Avatar
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    Fabriano Aristico will require acidification.

    I use a 10% solution of Oxalic Acid (100g per liter), and brush coat this onto the paper. You can use your coating brush - there are no issues as long as you rinse it afterwards. I don't count drops -- just dip and coat until you have covered the surface. You will see little gas bubbles in places where a chunk of basic coating is neutralized. Just don't put so much on that oxallic acid is crystallized on the surface after drying.

    After coating the paper, hang and allow to dry. Keeps forever.

    There is no need to wash the paper subsequent to the acidification.

  3. #3

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    Thanks Don, I will test your method althought the concentration you use sounds very high.
    Would surface sizing help? And humidification?
    gm

  4. #4
    Don12x20's Avatar
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    10% was the recommedation from Bostick-Sullivan when I received my paper. Works fine. They recommend 5% if you are going to soak.

    Surface sizing and humidification not necessary.
    I coat at about 60% humidity and don't humidify before exposure.
    YMMV

  5. #5
    Andrew O'Neill's Avatar
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    This thread got me to thinking...I have a bottle of oxalic acid. So, I went down to my darkroom, made up a solution of 10% oxalic acid and brush it onto the paper that I use for Kallitype printing (Rising Stonehenge, which is acid-free).
    Let it dry, coated it with sensitizer and exposed it. Once it hit the developer (sodium citrate), it stained like hell, with weird orange colour lines running through it. Yuck.
    I mixed up a 5% solution and soaked a sheet of paper in it and this time it worked not too badly but I could see very subtle uneven densities...maybe I didn't soak the sheet long enough in the 5% solution. So another sheet in the solution and I gave it an hour soak. This time it worked really well. Blacker blacks and nice cool tone.
    I then tried putting drops of the 5% solution in with the sensitizer. Ten drops (mixed in with 22 drops each of the ferric oxalate and silver nitrate solutions for an 8x10). It worked, but seems slightly grainy compared to the print that received the oxalic acid bath for an hour.

  6. #6
    scootermm's Avatar
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    coating the paper with oxalic acid seems (to me at least) a very inconsistent means of acidifying paper such as Fabriano Artistico.

    The intent of an oxalic acid prebath is to neutralize the buffering agent used in paper making.
    Most are buffered with calcium carbonate.
    Coating the sheet of paper with a brush dipped in oxalic acid seems like it would inconsistently neutralize this buffering agent.
    I would highly recommend that you completely immerse the paper in a bath of 5% - 8% oxalic acid. My normal procedure with Fabriano Artistico (Extra White is the one I use).. is to pre-bath usually 20-40 sheets at a time.
    I cut the 22x30 sheets in half to make 15x22 sheets. In a large grout mixing tray I make up a big ol huge bath of 7.5% Oxalic acid. usually in the range of 8L +/- and then put each sheet in one by one until all 40 are in there. Then I'll usually shuffle from bottom to top a couple rounds (usually 4-5) then pull the out and hang them to dry.
    Makes for nice consistent results.
    Nigel Tufnel: It's like, how much more black could this be? and the answer is none.
    None more black.

  7. #7

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    I put my Fab EW through 1% oxalic acid for 3 minutes...works great though some batches, I am told, need more occasionally. I refresh after 1-2 22x30 sheets of the 300gsm (140lb) variety. I rarely pre-acidify more than this...so far.

  8. #8
    Andrew O'Neill's Avatar
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    Coating the sheet of paper with a brush dipped in oxalic acid seems like it would inconsistently neutralize this buffering agent.
    That is exactly what I found, too.

    I'm now trying out a 1% bath. I think the secret to success is a long soaking time.

  9. #9

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    I have only brush coated once. I used a 10% solution of oxalic acid. When it dried, it left visible crystals on the paper. Not sure how to get around this, but maybe using less would have helped.

  10. #10
    Andrew O'Neill's Avatar
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    What if you resoaked the paper in plain water?

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