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  1. #11

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    Yes, that's definitely a carbon black, and a very high-contrast mix for sure. Just goes to show it really helps to see what a person is talking about, as I had assumed you were talking about a black for a one-coat gum, where you would want more of a range of tones. I'm pretty sure you couldn't get that black a black with this PBK 11, although you certainly could with lamp black. In watercolor paint, the Old Holland "vine black" is the only paint that's manufactured in the charcoal pigment PBk 8, which is sometimes called "vine black" but with powdered pigment you may have more choices in that pigment. But PBk 8 is semitransparent; the black in your picture looks quite opaque. Lamp black, also sometimes called "blue black" is very opaque and widely available in both paint and powder and is probably your best choice to replicate that look, unless you can find out where Chia gets the "kimrok."
    kt

  2. #12

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    I got curious to see how much darker I could print the PBk11 if I was willing to give up gradation of tone, but ran into problems. The Winsor & Newton "mars black" may work better, but I found that the tendency of the Daniel Smith paint to granulate and reticulate due to the magnetic properties of the iron particles (described on handprint) made it print unpredictably at stronger concentrations, although one might like to exploit this effect for more "artistic" efforts. So I don't think I would recommend the Daniel Smith "lunar black" for a high-contrast black, although it seems to work fine in a more normal-contrast mix as shown earlier. I believe this may be the first pigment I've ever run across that I would say is problematic for gum printing.
    Attached Thumbnails Attached Thumbnails PBk11b.jpg  

  3. #13

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    Actually, I had some problems with flaking using the "kimrök" on another print. I think it was a mixture of kimrök and a cyan pigment that flaked a bit. In the end I think it added to the print, but maybe the cyan (or blue) was iron based and caused problems?

    I just took a second look at all the prints I made with Chia and it's very very obvious that the kimrök pigment is superior to the lamp black we were using at the time. The difference is staggering. I must get back to Chia and ask her what tube paint it was, and steer clear of it! :-)

    Thanks Katharine for all the trouble you went through to clear things up for me!
    Be careful his bow tie is really a camera
    timeUnit

  4. #14

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    Flaking v "reticulation"

    This is an interesting question, because I've never seen this with Prussian blue, an iron blue that I'm very fond of and use a lot, and because according to handprint it's only the Daniel Smith iron oxide black that evinces this reticulation thing; the Winsor & Newton version of the pigment is said to be relatively free of it. And the earth pigments, which are mostly iron oxides of one sort or another, don't do this. So why would just this one iron pigment, in this one formulation, be so subject to this effect? Beats me.

    But I'd make a clear distinction between flaking and the reticulation I'm talking about; they're not the same thing. In experimenting with trying to find a high-contrast mix of the "lunar black," that would work well, I encountered both phenomena. I'm afraid the jpeg I posted before didn't show the reticulation very well, so I've posted another attachment below that shows a 1-inch section of the same reticulated print, enlarged, next to a 1-inch section of a flaked print, enlarged to the same degree, so you can see how different they are. When a gum layer flakes, it first forms blisters, then pulls off the support, then breaks into pieces. In this reticulation thing, the layer stays on the surface but becomes sort of crystallized and rearranged.

    Flaking is a potential problem any time you start really loading the gum up with pigment,, even when one extends the exposure sufficiently to expose completely through the thick layer, (as was true of the example shown here) and this is true with any pigment. Any time there's so much pigment in the gum that it feels more like brushing on a printing ink than brushing on a usual gum layer, there's the potential for flaking.

    I always enjoy talking about gum issues with other gum printers.
    Attached Thumbnails Attached Thumbnails Flakecompsm.jpg  
    Last edited by Katharine Thayer; 07-14-2007 at 03:19 PM. Click to view previous post history.

  5. #15
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    Quote Originally Posted by Katharine Thayer View Post
    Flaking is a potential problem any time you start really loading the gum up with pigment,, even when one extends the exposure sufficiently to expose completely through the thick layer, (as was true of the example shown here) and this is true with any pigment. Any time there's so much pigment in the gum that it feels more like brushing on a printing ink than brushing on a usual gum layer, there's the potential for flaking.
    Correct me if I'm wrong, but didn't Demachy and Puyo manage to create finished gum prints with one application of the gum/pigment mixture? If so, they must have had a lot of pigment in the mixture. How did they avoid the flaking?

  6. #16

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    Katharine,

    the issue I had was definetely flaking, and not reticulation. But again, it was over a year ago I made the prints, and I have not started doing it again yet. I don't know if the blue/cyan pigment used at the time was iron based.

    All my gum prints (it's only five so far!) are three or more layers. The flaking print was given two more prints with kimrök, and the flaking was largely covered, leaving only a faint hint.

    Thanks again for your time!
    Be careful his bow tie is really a camera
    timeUnit

  7. #17

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    Quote Originally Posted by Chazzy View Post
    Correct me if I'm wrong, but didn't Demachy and Puyo manage to create finished gum prints with one application of the gum/pigment mixture? If so, they must have had a lot of pigment in the mixture. How did they avoid the flaking?
    You're not wrong about Demachy and Puyo making one-coat gums, but the assumption that they must have used a great deal of pigment to make them doesn't necessariily follow. I don't know that I've ever seen any of Puyo's gums, even in reproduction, but Demachy's one-coat gums don't appear to be very heavily pigmented at all; their tonal scale doesn't indicate to me a pigment load where flaking would be likely to occur.

    The kind of pigment load that will print the deepest most opaque blacks such as timeUnit's ships, won't print more than a few tones (that's why I referred to it as a "high-contrast mix") so if you used it for a one-coat, it would be a very posterized, graphic kind of print. This kind of mix is most often used as it was used in that print, as the K layer of a CMYK print, or to lay in the deepest shadows in a multiple print that spans a full tonal scale. It's not the kind of pigment load you'd use for a one-coat gum where you wanted to express the widest possible tonal range in one coat; you'd use a less concentrated pigment mix for that. For example, the one-coat work print I did yesterday to demonstrate how PBk11 looks in a gum print, was made with a mix that looked solid black in the mix, but printed a fairly normal range of tones. (Not a very long tonal scale, but about as much as gum can manage in one coat). But to add a deep black to the print, you'd need a separate printing with a heavier pigment load. It's the tradeoff you always have with gum; you can have drama or subtlety in any one gum printing, but never both. Demachy tended to go more for subtlety.

    It's this kind of heavier, high-contrast pigment mix that has the potential of flaking. I was experimenting with heavy loads like this yesterday when I was checking out a high-contrast mix for the lunar black; about half of my test prints flaked and half didn't, and whether they did or didn't wasn't discernably related either to the amount of pigment or the amount of exposure, and that's been my experience with printing with these heavier mixes. Sometimes you get lucky; sometimes you don't. But these mixes were so stiff it was like like trying to spread printing ink with a brush; most gum printers aren't ever going to try to print a mix that heavy.

    I hope that somewhat answers the question,
    kt
    Last edited by Katharine Thayer; 07-15-2007 at 01:00 AM. Click to view previous post history.

  8. #18

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    Correction re Demachy

    Quote Originally Posted by Katharine Thayer View Post
    You're not wrong about Demachy and Puyo making one-coat gums, but the assumption that they must have used a great deal of pigment to make them doesn't necessariily follow. I don't know that I've ever seen any of Puyo's gums, even in reproduction, but Demachy's one-coat gums don't appear to be very heavily pigmented at all; their tonal scale doesn't indicate to me a pigment load where flaking would be likely to occur.
    kt
    I got to wondering if I was misremembering and inadvertently misrepresenting Demachy, so went looking for what reproductions I have on hand. I can't find my little Taschen book of his work, but I looked at what there is of his in the big book of reproductions from Camera Work, as well as his published instructions for his method. In my earlier remarks, I was thinking of such things as Study in Red, which has nice tonal subtlety within a not very wide tonal range, in other words the usual one-coat gum tonality.

    But I was forgetting a lot of work he did that wasn't much different from other gum work of the time: heavily pigmented, coarse and lacking in tonal range; essentially a dark tone with a few lighter tones introduced by forced development. Both types of print seem to illustrate my point about pigmentation and tonal range: less pigment=more tones; more pigment=fewer tones.

    As for how he dealt with the danger of flaking, he dealt with it by making sure his mixes were liquid enough to spread out thinly (in other words, not overly pigmented). "Most failures in coating are due to an exaggerated thickness" he wrote. He adds, correctly IME, that some pigments require a higher pigment/gum ratio to get the same depth of color than others, and recommends adding more dichromate to those mixes to thin them to a good brushing consistency. "It follows, therefore, that more bichromate has to be added to a sepia mixture to dilute it to proper fluidity than would be required for lampblack, because the smaller bulk required of the latter gives a much thinner consistency." His black of choice appears to have been lamp black, which as he says, requires little pigment to produce a solid black. This iron black I've been working with for the purpose of this thread, as I mentioned earlier, requires a lot more pigment to get the same solid black as one can achieve with a lesser amount of lamp black, and that's why I've been struggling with these very stiff mixes. His recommendation to add more dichromate than usual to dilute a heavily pigmented mix is interesting, because (1) adding liquid would dilute the saturation of the pigment, somewhat defeating the purpose, one would think, and (2) because adding more dichromate would decrease the contrast, which would be a good thing, working against the tendency of heavy pigment mixtures to produce very high contrast prints. It might be worth a try, if anyone is really interested in using this black. My recommendation would be to forget it and stick with lamp black, if you want a neutral black, or ivory black if you want a warm black. I'm fascinated with this black of Chia's; it sounds like a great black, whatever it is.

    As for Puyo, if "Against the Light" is a one-coat gum print, that's one heckuva gum print. (Camera Work doesn't identify the process used to make the original prints, only the printing method used for the reproduction).

  9. #19

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    Regarding Chia's black: I'm quite sure she stressed the use of a pigment, not a tube paint, to get the black she preferred. She also mentioned what you found, sometimes it flakes, sometimes it doesn't. It's not directly related to the amount of pigment you put in your gum mix.

    And I'm quite sure the pigment is of carbon, as you mention.

    I will contact her and get some more info on the specific pigment she's using. Chances are quite big though that the maker/brand of that particular pigment is not available anymore. But there might be a subsitute somewhere! :-)
    Be careful his bow tie is really a camera
    timeUnit

  10. #20
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    Katharine, thanks for all the information. By the way, I followed the link to your gum bichromate page and it's great.

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