Re: Taming Fabriano Artistico (Trad. White) for Cyanotype
3 Aralık 2008, Çarşamba, 5:55 pm tarihinde, Paul Viapiano yazmış: > The reason I use oxalic acid and not HCl is because of its relatively > benign > handling characteristics. By comparison, HCl is just too dangerous a > chemical to have in a darkroom located in your everyday household. I already explained why I don't prefer oxalic acid. And diluted HCl is a common household item here in Turkey, in form of toilet / tile cleaner... > The whole idea of paper acidification is to lower the pH of the paper > and/or > remove the excessive amounts of carbonate coating manufacturers use in > order > to achieve the almighty 'acid-free' status, in order to be amenable to the > acidic solutions we use. So, I don't think there is an advantage to using > a > much stronger acid. After all, acidic soaking aolutions of only 1-8% are > used by printers worldwide with wonderful results. Not only oxalic acid > can > be used, but citric works very well, and I even used a very dilute > solution > of Kodak Indicator Stop Bath once. It worked wonderfully...and I would > expect plain distilled white vinegar to work as well. I'm not advocating usage of strong concentrations of HCl, that can be obtainable in non-fuming form (ca. 10 - 15%). I happen to have concentrated on hands, that's why I'm using it. And I dilute it pretty much (0.35M, ~ 1.2%, if I'm not mistaking... I use 50ml of 35% solution in a total volume of 1000ml -> you can do the math yourself if you like...) Citric acid works fine indeed but it has its own problems such as: making clearing harder, lowering contrast and prone to stain and/or bleed, depending on the amnt. one uses and the specific paper. You're right about acetic acid being a better / safer alternative (it was brought into consideration a month or couple ago) but I don't agree on vinegar. (As long as it isn't a pure solution of acetic acid; to my knowing vinegar is not pure acetic acid and contains other compounds... I'd rather use something pure w/o any alien compounds, especially in the context of Pt/Pd printing.) > Try amending your coating with a drop per ml of Tween or Photoflo at 10% > to > help prevent runoff in the first wash...works wonders for me. Thanks, I know that trick and used it extensively (in form of Ilfotol)... I don't have bleeding problem and or blue wash water with HCl treated Fabriano Artistio TW -> I noted this because I was surprised that I haven't had it. Regards, Loris.
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