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Zinc Oxide – Reviewing the Research

14 thoughts on “Zinc Oxide – Reviewing the Research”

  1. Pingback: the philluxist
  2. Sarah, this is a wonderful and very complete article! More than that I would say a terrific paper!
    Anycase, thanks to put all this together.

    I have a side question regardin umbers. I read a couple of papers of Marion Mecklenburg about the flexibility but little strenght of the umbers. Do you think that could be a serious concern to paint with them, specially in the underlayers?

    Thanks in advance. I read your articles and facebook post and always find them very clear and precise, with the best up to date data!

    Reply
    • Hi Ariel –

      Thank you so much for the warm words about the article. I truly appreciate it!

      While it is true that in Mecklenburg’s research umbers are shown to be vulnerable to solvents and do not form strong films, that does not necessarily mean they cannot be used. Weak films in this context are not necessarily brittle ones, like zinc oxide, so should not increase the likelihood of cracking. And of course they are wonderfully fast drying colors, so from that standpoint are very helpful in underlying layers. Lastly, while the studies are looking at films of umbers by themselves, painters rarely use them that way. Blending them with white or other colors, adding mediums, or simply using them to form a sort of imprimatura, all should lessen or at least change the risks.

      In any case, I have reached out to Mecklenburg to get his thoughts on this as well, since you are responding to his research, and will report back what I hear.

      Reply
      • Wonderful to read that Sarah. All the work you do (and other specialist in Mitra) and people like George O’Hanlon is truly appreciated and significative for oil painters!
        Again, love your articles.

        Reply
  3. Thanks for this complex article. I’m assuming that in acrylics, the zinc whites wouldn’t have the same brittle effect, since they dry and harden quite differently.

    I notice that in the Color of Art Pigment Database, there are quite a lot of white pigments listed. Would there be any other candidates among these to add to the oil painter’s toolbox? Obviously, since such choices aren’t currently on sale, there must be difficulties, but it’s hard to distinguish why that would be.

    Thanks again, I enjoy learning the mechanics as well as the aesthetics of artwork, and these videos and articles are great resources.

    http://www.artiscreation.com/Color_index_names.html#.V5YCQ5DEirU

    Reply
    • Hi Holly –

      Thanks for the comment. And yes, you are correct, the issue with zinc is solely with oil paints and it is not a problem in acrylics, or for that matter, watercolor.

      In terms of the Color of Art Pigment Database, and all the whites listed, keep in mind that pigments assigned a color index number are not necessarily meant for artist use, or even in the paint industry per se – they merely denote the assignment of a reference number by a trade group made up of the British Society of Dyers and Colourists and the American Association of Textile Chemists and Colourists. So they represent quite a broad interest, and only some of these are ultimately useful for painters. Sometimes it can be because of chemical interactions, lightfastness issues, toxicology, or a pigment might be useful in a water-based system but not in an oil one due to refractive index. For example, calcium carbonate and many other chalks can serve as a white in highly pigmented water-based systems, like casein, but will often just produce a grayish translucent color in oil.

      Anyway, to sort through the reasoning would require going through them on a case-by-case basis, but certainly, paint manufacturers are constantly on the lookout for alternatives and will sometimes look to this list for options. For example, we recently revived the use of lithopone (PW 5) as a white pigment, using it in our safflower-based Porcelain White. Lithopone had a very prominent role in the commercial paint industry until titanium white came along in the 1930s, and we felt it provided a safer translucent option when compared to zinc. And there might be some others worth revisiting, but nothing on the immediate horizon.

      Reply
  4. Hello!
    Is there a better solution as the first, thick, white impasto layer, than PW6 + PW4 in linseed oil (with a little stand oil with turpentine as a medium)? (Colored glazes go on that).

    Reply
    • Hi PW –

      Thanks so much for the question. Unfortunately, at least for most people, the absolute best option would be to use a linseed-based lead white, like our regular Flake White. Lead whites made with linseed form the most durable and flexible films. After that, you would be better using a Titanium White in linseed but without any zinc. Again, our Williamsburg Titanium White would be a good choice here. The main concern with the choice you give is the inclusion of zinc oxide, which can make the paint film much more brittle over time. hopefully one of those options will work for you. if you need more help just ask!

      Reply

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