DTM Bonding Primer by Sherwin Williams - presence of zincApproveRejectUn-ApproveSubscribeUn-Unsubscribe
Question asked 2021-02-24 01:07:40 ...
Most recent comment 2021-02-26 17:45:54
Art Conservation Topics
Grounds / Priming
Scientific Analysis
In a number of places you recommend DTM
Bonding Primer by Sherwin Williams as a ground, particularly for use with aluminium panels.
The EDS data sheet suggests it
contains zinc.
Zinc (as Zn)
2% by weight
Zinc Compound
3% by weight.
https://www.paintdocs.com/docs/webPDF.jsp?SITEID=SWPCGPROT&doctype=EDS&prodno=035777281734&lang=2
In dry form the percentage of zinc will be much higher.
Yet elsewhere you frequently warn to check for zinc content. For example in your Grounds and Primers technical resources state: 'Zinc white has been found to react with components in oils and alkyds and form “metal soaps,” which in turn can give rise to delamination, wrinkling, the formation of white-colored aggregates, and the softening of ground/paint layers. Research is presently being carried out to determine the extent of damage that can occur when these materials are present.'
Can you please clarify? Is the zinc in a different form or are there other reasons why this product is suitable despite the presence of zinc? Have I misread the EDS - I'm not a chemist! There are a number of people on my forum (Wetcanvas) discussing this and we are interested in the clarification.
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Moderator Answer
(brian baade)
Zinc oxide has only been shown to be problematic bound in drying oils, not acrylic dispersions/emulsions like the one used in the SW product.
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Moderator Answer
(george o'hanlon)
One thing to note is that the datasheet does not specify the zinc compound. We cannot assume it refers to zinc oxide. Onnly zinc oxide is known to form zinc soaps that pose problems in oil paint.
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Moderator Answer
(mkinsey)
Thank you, George, I was thinking the same thing but was not confident enough to post as a verified fact.
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