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Question asked 2020-11-23 11:50:16 ...
Most recent comment 2020-11-24 07:09:57
Pigments
Egg Tempera
According to recent research, zinc white (PW4) causes saponification in connection with oil paints. This means zinc white can cause long-term damage to the image. Is this also the case with zinc white and egg yolk tempera? And how does it look like in connection with tempera grassa?
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Moderator Answer
(brian baade)
In general, I caution against using zinc white with any
medium that contains free fatty acids if there are reasonable alternatives.
This includes drying oils, egg yolk, mixtures of those two, and possibly even
encaustic. This is probably overreaching and there are times when titanium
white is not appropriate. It also suffers from deficiencies, especially in
drying oils where it makes a very poor film. This does create a situation where
there are compromises either way. I will
contact individuals in the industry to give their perspective.
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Moderator Answer
(george o'hanlon)
We have not seen any studies that indicate problems with zinc oxide in egg tempera, but caution is appropriate based on the formation of zinc soaps in lipids and fatty acids. In addition, the use of zinc oxide in egg tempera has not been as widespread as in oils, so we may not be aware of any issues at this time. The precaution would be more important with tempera grassa since this medium employs drying oils.
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