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Question asked 2017-02-28 08:31:01 ...
Most recent comment 2017-02-28 10:55:00
I stopped using a newly opened large tube of Windsor and Newton titanium white that I had on hand because it contained "a small amount of zinc" according to the manufacturer. I suspect there is a growing amount of zinc containing paint being abandoned. Obviously, pure zinc white is disocuraegd but it would be great if there was some sort of guidance as to how much zinc is acceptable in a multi-pigment colour. In medicine there is an expression that goes something like "the dose makes the poison". Similarly, I expect that a very small amount of zinc isn't going to cause a problem but I haven't seen any research or guidance as to just what that maximum tolerance for zinc is. Is there any current guidance on this or research that you know of under way to clarify this issue?
Answers and Comments
Yes unfortunately this is an issue that will continue to plague those who paint in oils/alkyds until more research can be performed. FYI if you enter "zinc" in our search field you will earlier threads where folks have expressed the same concerns. I am sad to state that in conversing with some paint manufacturers recently, percentages of zinc even below 15% in oil paints are showing an increase in brittleness and a propensity for cracking. If you do choose to use paints with zinc in them it is best to stick with rigid supports. I will paste one of my previous responses from one below:"
But certainly issues have been observed even when zinc white is mixed together in small quantities with titanium or lead (studies performed by Marion Mecklenburg, published in 2008). However, I am also one to state that in conservation we are very prone to basing everything on one single study, which from a scientific standpoint is not always the best approach. This is mostly due to the fact that we have limited resources (meaning funding) as a field. Studies focusing on zinc white need to be repeated in order to truly confirm some of these findings (not that I disagree with them outright by any means). That being said there are really no "best painting practices" alternatives at the moment...until the paint industry and/or conservators and scientists are able and/or willing to perform additional tests we will simply have to wait. For the moment a good rule of thumb regarding zinc white is the less you use the better....but if that is not a good solution you can also simply record your use of zinc white and other materials on the reverse of your painting. This will give future conservators the information they will need when addressing how best to care for your painting should future issues arise (and if your painting is professionally executed and well cared for there may not be any issues!)."
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