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Old 10-08-17, 02:10 PM
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Koo Schadler Koo Schadler is offline
Tempera Painter
 
Join Date: Dec 2003
Location: Alstead, NH & Zirahuen, Mexico
Posts: 299
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Hi All,

George sent the following replies...

1. Is the concern of cracking due solely to the high solid content in the Tempera Ground, or also a consideration of the binder?

"The high pigment volume concentration of Rublev Tempera Ground makes it less suitable for flexible supports and more likely to crack on these types of supports. However, Rublev Tempera Ground is much more flexible than a traditional chalk or gesso ground. The polymeric binder is very flexible similar to the flexibility of acrylic polymers."


2. Why is backing a flexible support with a solid support (paper on wood panel) potentially not enough to prevent cracking?

"A rigid support decreases the exposure of hygroscopic materials (paper) and hence reduces the degree to which these materials expand and contract due to changes in relative humidity, but does not prevent the paper from expanding and contract."


3. Any reason(s) to coat paper with either the Fluid Medium or GAC 100 when using NP's Tempera Ground as a base for metalpoint drawing?

"This is not necessary when using Rublev Tempera Ground."


4. I'm thinning Tempera Ground with water when building up multi-colored layers for a drawing because I want to apply the thinnest possible layer. The Natural Pigment's website says don't thin more than 20% with water, further dilution can be achieved with the Fluid Medium. What are the consequences of adding too great a percentage of water to the ground - underbound, cracks, flaking?

"The consequences may be underbound ground, depending upon the absorbency of the substrate."


5. At some point does the ground cure and is no longer water soluble (and thus not dissolved by wet sanding)?

"The polymeric binder in Rublev Tempera Ground is not water soluble once it has dried and will not redissolve by wet sanding. However, care must be exercised when wet sanding to avoid excessive moisture and/or heat as this cause the binder to “gum” up no the sandpaper."
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