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  • PBr33 zinc iron chromite - in oilsApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2017-06-26 03:39:20 ... Most recent comment 2017-06-28 18:42:30
    Oil Paint Pigments Scientific Analysis
    Question

    ​Hello,

    I'm interested in using PBr33 due to it's very dark opaque nature.. It's used by Sennelier and Schmincke in a few of their oil paints. However as it's made using Zinc I'm just concerned it could make the resulting paint film brittle in the same way zinc white can.

    But I don't know if the combination with the iron and chromite would avoid this issue.

    Does anyone have any opinions on this?

Answers and Comments
  • EditDeleteModerator Answer

    ​The form of zinc that is a concern is zinc oxide, because of its reactivity with fatty acids, but zinc in and by itself is not necessarily bad and you always need to be aware of its form and how it is occuring. For example, zinc sulfide is considered nonreactive and not associated with soap formation, while zinc is also used to modify other metallic crystals in order to create a specific color. The most common one you might be aware of is cadmium zinc sulfide, where the zinc is imbedded into the structure of the cadmium sulfide crystal to produce various shades of yellow. In the case of PBr33, the zinc is modifying the iron chromite and in the process produces various shade of brown but the resulting crystal is considered a stable formation and does not present the same issues as zinc oxide on its own.

    Hope that helps.

    Sarah Sands
    Senior Technical; Specialist
    Golden Artist Colors

    Sarah Sands, Senior Technical Specialist, Golden Artist Colors
    2017-06-26 08:44:32
  • ApproveRejectUn-ApproveUser Comment

    ​That's great news.! Thank you very much Sarah :)

    2017-06-26 10:57:37
  • ApproveRejectUn-ApproveUser Comment

    ​Hi Sarah,

    Could zinc sulfide possibly replace zinc oxide as an addition to titanium white, ie. to mitigate the "sponginess" of straight titanium?

    2017-06-27 21:00:42
  • EditDeleteModerator Answer

    ​Not really in my opinion. Zinc has a unique hardness that, alas, is also part of its Achilles heel. From very early on zinc was used in coatings to lend a harder, and in commercial paints, more scrubbable, dirt resistant, and physically durable film. Particularly as an adjunct to Titanium White. But I am not aware of a comparable pigment that can fill the same roles. Alkyd medium can lend some film hardness, if adding a medium is an option for you. And of course, unless used alone, Titanium White in blends will be influenced by whatever you mix it with.

    Sarah Sands, Senior Technical Specialist, Golden Artist Colors
    2017-06-28 11:06:50
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks, Sarah.

    2017-06-28 18:42:30
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