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Thread: Pigments

  1. #1
    bob carnie's Avatar
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    Pigments

    Hello All

    Bmikten started a thread about where our work should end up and I and a few others hijacked it and turned the discussion about pigments , which I apologize for.
    I would like to talk about pigments, not dyes, and how people work with them ways of staining wood, ways of printing with them, ideas on how to crush stone and make to paste, basically
    use this thread to gain more information about them.


    I will start it here with a post by Drew W.

    That technique is called "ebonizing". But there are much safer and less expensive formulas than the dichromate route, easily searched on the web. The wood itself needs a high tannic acid content. So some wood species darken far more than others. But using such a solution also raises the grain, so you have to polish or fine sand everything down again afterward, prior to a final sealant. A major wholesale frame factory in this area had a lot of demand for that, with one employee dedicated to it almost full time. But due to the substantial extra cost of the appropriate hardwoods, as well as extra labor expense, they eventually switched entirely to Black Cat ink for their opaque black wooden frames. However, a partial chemical ebonizing might simulate ammonia fuming of white oak without the awful health risk involved with that.

    Now as per that linked insane "death wish" toxic voodoo method of enhancing cherry ... escape the Medieval Inquisition torture chamber and acquire a modern transoxide colored sealant. I've used something called Cetol 1 for both personal picture framing and cabinetry needs, as well as massive architectural restorations (including one entire Frank Lloyd house, inside and out, plus furniture - a six million dollar renovation project). It's totally lightfast, truly transparent, penetrates deeply, and is dispersed in oil sealant, so allow it to thoroughly outgas before putting artwork in the frame. There is also a water-based equivalent, but it's not as deluxe to apply.

    And yeah, it might be nice to section all this off to a separate thread.

  2. #2
    Drew Wiley
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    Re: Pigments

    OK - to supplement that, the most advanced pigment research naturally applies to where there is the most financial incentive - auto paints, and namely, where a deep translucent or transparent "3D"look is desired instead of an opaque one. Transoxides can be made in almost nano scale, so tiny as to be transparent, so might be of interest in alt photo applications. The down side is that, being oxides, no reasonable process set is possible. You could achieve an off-color image, kinda like an exaggerated version of Godfather movie filtering, or some other fun effect. And I don't know if some of these might "poison" gelatin and cause carbon or carbro gelatin to prematurely cross-link and embrittle. But in terms of wood finishes, this category of commercial pigments offers all kinds of opportunities.

    In terms of industrially available pigments of well-tested lightfastness and high batch to batch consistency, the finest ground are probably Genex. And in that case, a true non-toxic process set is feasible.

    Rockhound style mineral hunting can be fun. My dad was into that, and would take me out of school for weeks at a time, touring the deserts and mountains. I learned more from him anyway. I once took a bizarre shot in Utah of bright blue gopher mounds atop a red clay alluvial wash, due to them burrowing into a different layer below. All kinds of interesting agates and calcites were laying around too. In that general area, there are places where different colored sandstones layers are each only several inches thick, and are sometimes exposed adjacently : purples, turquoises, deep blues, reddish tones. Some interesting days packing in big cameras, that's for sure.

    A pal of mine up the hill built their own house using trucked in Moenkopi red sandstone, Brazilian granite, and personally milled cherrywood cabinetry. I supplied them with the specialty transoxide finishes, which could be layered up to an excellent match. But he wanted unique cabinet knobs, so as an outdoorsmen himself, explored creek beds in the desert of Baja California, and came back with reddish "desert varnished" pebbles which matched his woodwork, and could be epoxied onto his cabinet doors and drawers using metal stems hidden behind. The coolest part of the project was their master bathroom. He took a color panoramic photo of the east side of the crest of Sierra at sunset, then replicated that using overlapping various shades of marble, broken or otherwise shaped to match the scene.

    I've been involved with many many analogous projects. In fact, the same chemical supplier which catered to the local pharmaceutical industries supplemented their business not only selling darkroom chemicals, but all kinds of coloring substances coveted by metal platers, potters, stained glass craftsmen, and classic faux finishers. No longer in business due to a premature family death. But everyone who worked there, even at the sales counter, had a phD, so had serious knowledge of their products. At a more down to earth level, the thick venerable The Artists Handbook, which has gone through many revisions, is an excellent introduction to artist pigments per se.

  3. #3
    bob carnie's Avatar
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    Re: Pigments

    Thanks Drew, though rockhound style mineral hunting is not what I intend to do I actually have some friends and clients that may be willing to do a bit of this. I really like the idea of getting down to the key basics, the post in the other thread blew my mind about potassium dichromate as a vehicle for staining cherry wood for example, I have been trying to understand the relationship between Gum(tree sap) Ammonium Dichromate and UV light and in this one post I saw the link to how it all works.
    I do not come from a well educated background, but rather school of hard knocks so I love this learning experience later in life and when I can put two and two together to equal four, well is very satisfying.

  4. #4

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    Re: Pigments

    I'll follow this thread with interest! I don't have much to contribute as I have only an elementary knowledge of pigments as it stands, but they've always fascinated me.

    I do have a probably easy question concerning pigments for B&W carbon transfer. I'm looking for a good neutral to cool black pigment, preferably already dispersed, so something like watercolor paint or whathaveyou.

    So far I've been using Talens India ink and acrylic paint. The India ink works very well and is technically superior to the acrylic, which seems to have some additives in it that create a very, very faint oily veil on the tissue, and it also shows up on pure whites very faintly. Otherwise it prints OK, that is at least lamp black. I've also tried oxide black (essentially iron oxide) and it's more problematic; it seems the dispersion isn't nearly as good as that of the lamp black paint and the India ink. It doesn't seem to create very big problems in the print and the print tone appears to be perfectly neutral, but I expect the tendency of the pigment to coagulate and/or the variations in particle size will at some point result in problems in the highlights.

    I'm located in Europe so not all products may be available to me. Worst case scenario I'm prepared to make my pigment dispersions at home, but I'm painfully aware of the complexities of doing so, hence my preference at this point for an already dispersed form.

    PS: I can of course add colored pigments to lamp black to shift the tone, and if there's really no other option I'll keep doing this, but I want to explore the possibilities of a truly neutral pigment.

    PPS: The Wet Print (based in Spain) I know sells a very nice pigment, but (1) it's lamp black so warm-toned, and (2) they recommend the very ink I had already been using for carbon transfer.

    PPPS: I'm aware of the existence of other varieties of essentially burned stuff; i.e. vine/vineyard black, ivory black etc., and while some are a tad more neutral than lamp black, they're all distinctly warm-tone.

  5. #5
    Drew Wiley
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    Re: Pigments

    Lamp black is inherently purplish, and mineral blacks are distinctly greenish. I have a lot of background in industrial pigments, and state this simply to hint that a paint store is not a good place to look for a photographic black. Pigment dispersion can itself be a complex science. With watercolor pigments, acrylics, etc you have to be careful no added preservatives like formaldehyde are present which can "poison" the gelatin. Sandy King once hosted a Carbon Printing forum which discussed a lot of this kind of thing.

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    Re: Pigments

    Thanks Drew, yes, I'm aware of these challenges. Btw, the iron oxide black I tried is neutral enough; if there's a greenish hue to it, it's sufficiently subtle not to be objectionable. Other than that, I agree that the local arts supply store may not offer the best solution. They have a wide range of pigments, 7 or do of them are black, but none of them qualifies. As to the paints they stock, the selection is naturally narrower.
    India inks btw are also a mixed bag; I trialed those when I first started out with carbon printing and found that several were combinations of a black pigment and dyes to shift the color in the desired direction. All of these dyes stained the paper badly, of course.

  7. #7
    Drew Wiley
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    Re: Pigments

    There are so many kinds of inks too. Fortunately, some very skilled carbon printers participate in this forum and can probably answer your questions about that aspect. I have sometimes worked with inks in relation to woodworking; but that's something quite different. I never got past certain process color experiments in carbon, since I planned to dedicate the time to learning dye transfer printing instead, which is capable of great depth of black without resorting to a K printer. But alas, even that has fallen through, schedule-wise, once I got into making high quality internegs suitable for advanced levels of chromogenic printing. Maybe in another lifetime.

  8. #8
    Vaughn's Avatar
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    Re: Pigments

    For a neutral black in my carbon prints (single transfer) I have found the watercolor lampblack in tubes to be excellent. I have been using Grahams...but that is a west coast USA company and probably not available across the sea. I started off using Grumbachers Academy grade lampblack. No issues.

    The pigments of watercolors in tubes is finely ground, well dispersed, consistent, and easily to measure and use. A little more $ than doing everything yourself, but the cost is a minor expense when taking in everything else. Also depends on one's volume of work produced, of course.

    I often add a little Burnt sienna or similar for a little warmth.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  9. #9

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    Re: Pigments

    Thanks for chiming in Vaughn. I'll have a look at the watercolor selection down at the shop next time when I visit town; probably next week to pick up some prints they're framing for me. I wonder if the lamp black in Graham's is cooler in tone than what I get from the acrylic paint I'm using. Btw, the acrylic lamp black is already considerably more neutral than Talens India ink, but still distinctly warm.

    You're certainly right about the chore of making a good dispersion vs. getting one that's pretty much ready to go. Cost savings aren't my motive; it's just that so far it seems hard to find a finished product that offers the tone that I'm looking for.

    @Drew, yes, color carbon...that's something else. I know I would have to go through digital negatives to get that to work, realistically. And that's a rabbit hole I'd prefer to avoid for now, if I can. Maybe, one day. For now I'd just like to become proficient enough in B&W carbon so that I can fairly reliably select the right tissue, sensitizer concentration and exposure time based on any given negative I make. I'm right now looking at a 4x5" carbon transfer onto glass that I made this morning; it has a few imperfections, but it has that unique quality that no other printing process seems to offer.

  10. #10
    Vaughn's Avatar
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    Re: Pigments

    I tried a French brand of lampblack watercolor (starts with an "S") that was very warm -- closer to what I have found with Ivory black. So there seems to be a variation in what lampblack actually is.

    Some folks will add a little blue of some type to counter any warmth. I find Black Cat to be too warm (and glossy) on its own for me. But I have used Sumi ink in the past -- on its own (very warm, of course) but also to mix with lampblack to add a little warmth.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

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