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  1. #71
    Herzeleid's Avatar
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    If you washed the paper thoroughly afterwards, the paper should not be acidic. Acidic papers would cause fogging especially sulfamic acid and modern cyanotype combination (any other AFO using process would act similar imo). Sulfamic acid is a very strong acid, but at room temperature it acts slow, at 70C it acts as fast as HCl. But the slow action is the advantage, it does not damage the paper's fibers much like the other acids.

    But you are right of course %1 would neutralize less alkaline content. If 1lt 1M SA solution (ca %10) can neutralize 14 papers, %1 might neutralize 1,4 papers (sheet size 56x76cm). But halfway through the life of the acid (0,7 sheets) the neutralization time would increase dramatically (almost doubles with some papers). %1 acid would work but for fewer papers, and I am concerned about the neutralization time and therefore consistency of the results.

    It would not effect traditional cyanotype and VDB adversely, but it is a problem for alkaline sensitive siderotypes.

    If I tested %1 SA for one sheet of paper (e.g. FAEW 300gsm), I would probably say it works but I am not sure overall it is a good practice, because compared to the second sheet in the same %1 the results would be inconsistent. I de-alkalise papers by batch, and %1 would not last for whole 2 sheets.

  2. #72
    Andrew O'Neill's Avatar
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    That's a very good point, Herzeleid.

  3. #73
    Andrew O'Neill's Avatar
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    For the hell of it, I acidified a sheet of Stonehenge in a bath of vinegar, diluted 1:1. Worked very well. Vinegar is heaps cheaper than sulfamic acid. Not yet sure of it's capacity, though, so more testing to do.

  4. #74
    Herzeleid's Avatar
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    Hello Andrew,

    Acetic acid would neutralize the buffer as well but I haven't tested it on purpose. My excuse is mainly the smell of it and in higher concentrations it would irritate respiratory system causing asthma like symptoms. Also it is weaker acidity and probably low capacity compared to SA. Vineagar is usually %3-5 acetic acid which is weaker than using concentrated acetic acid, and it still smells irritationg (especially if you are neutralizing a batch of papers). However, I must say calcium acetate is highly water soluble byproduct, which makes acetic acid/vinegar a better option than oxalic acid but cost wise vinegar's capacity won't match sulfamic acid.

    The part from my old post on the subject on vinegar.

    Sulfamic acid vs Acetic Acid/Vinegar (Rather, why I haven't tested it)
    -Vinegar is unreliable due to additives IMO, and the acidity changes from brand to brand
    -I did not want to try concentrated acetic acid due to its strong irritating odor.
    -Acetic acid is also a weak acid (around ph4 as I recal)
    -Byproduct of reaction is highly water soluble calcium acetate.

    That was it actually, why I haven't even tested acetic acid/vinegar. Strong odor, weak acidity and probable cost due to its weakness.
    I know some people use vinegar or acetic acid, and if it works for them that is great , but cost wise, I find SA to be a better choice.

    Regards
    Serdar

  5. #75
    Herzeleid's Avatar
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    Hello again,

    I made a quick search and it seems, 1M acetic acid (similar to vinegar) may neutralize similar amount of CaCO3.
    However I have no idea about the reaction times, and I have no idea how it would behave after the solutions starts to get loaded with calcium acetate.

    If you have tested it, how long did it take to neutralize the paper?

    But still the problem of irritating smell remains, and the shelf life. For me the smell is a major set back, it can trigger my allergies.

    Regards
    Serdar

  6. #76
    Andrew O'Neill's Avatar
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    At a 1:1 dilution, the smell was subtle. Reminded me of a salad with vinaigrette dressing! I would continue using sulfamic acid, but it's pretty expensive. One pound $10.

  7. #77
    Herzeleid's Avatar
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    That is expensive, I buy 1 kg (2,2 pounds) around $6. Once I tried vinegar for cyanotypes, I decided not to use it again

  8. #78
    Andrew O'Neill's Avatar
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    I just sourced a 25kg bag of SA for $44 CDN from ClearTech.. and the place is just down the road from me. No more Home Depot!

  9. #79
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    For calotypes, not cyanotypes, I've been using white distilled vinegar mixed 1:2 with water, 1 hour soak followed by 2 hours wash. I covered the tray while the papers were soaking and the smell did not bother me, I even like it a little... slightly fruity But if I had to mix acetic acid from my concentrate, it would be way too much and I'd try SA right away.

    After reading this whole thread a couple months ago, I went to the hardware store and found "dry acid" but the box did not say if there were other ingredients besides SA so I didn't get it.

    I've been meaning to go to home depot to get some, but the more I think about it, the more I think I will just stick to the vinegar. It works fine for my purpose: no more fogging problems, it's not expensive, and I always have some here anyway. I only acidify 4 or 5 sheets at a time, so cost and volume just don't come into play for me. If I start working in larger quantities, then I will reconsider SA. Just my 2 cents, and only for U.S version of Canson Marker paper and Greenlaw's calotype process.

  10. #80
    Andrew O'Neill's Avatar
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    If you have tested it, how long did it take to neutralize the paper?
    I left it (11x15 inch sheet) in for 5 minutes. Gave it a thorough washing afterwards.

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