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Old 29-06-17, 06:34 PM
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Koo Schadler Koo Schadler is offline
Tempera Painter
 
Join Date: Dec 2003
Location: Alstead, NH & Zirahuen, Mexico
Posts: 316
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Hello Rebecca,

When egg yolk and oil are combined it creates a emulsion paint, commonly referred to as "Tempera Grassa" ("fatty tempera", in Italian). If the % of yolk is greater than the % of oil, it's an egg oil emulsion and is water soluble. If there's more oil than yolk in the mix, it's an oil egg emulsion and is soluble in an oil solvent.

So, what's your percentage of egg and oil, and what thinner are you using (water or oil solvent)? If your paint is in the water soluble category and you put a layer of paint on top that contains water, the new layer will re-wet the underlying paint and can cause lifting. As any pure (versus emulsion) egg tempera painter knows, if you work the surface too much the underlying layers readily lift because they remain water-soluble until the paint has polymerized for a bit; it usually takes anywhere from a week to a month or more for polymerization to have sufficiently occurred so that underlying egg tempera layers are resistant to water.

Which drying oil are you using, and how long are you waiting between layers? If you are working with an oil egg emulsion (the paint has a greater percentage of resin and oil than egg) it should dry in about 24 hours or so (varies, depending on the oil), and after that the underlying layers should not easily dissolve.

A couple things about Mische: First, while it's sometimes touted as the working method of Northern Renaissance painters, there's no evidence to support this. My understanding is that is was developed by Otto Dix in the mid 20th c., in an effort to replicate the effects of northern painters. There isn't to say Mische isn't an effective technique that might be perfectly suited to your goals (or that you mentioned anything about its origins). I just want to clarify a common misconception about it.

Second, about damar: It is not an old master medium, as is sometimes thought; it first started to be used in the 18th century. The benefits of damar is that it dries to a hard, durable paint film fairly quickly (as soon as the solvent evaporates) and is sparkly and jewel-like initially. The problem is how it ages. Like all natural resins, damar yellows considerably over time and grows brittle; its life span is estimated to be as short as 20 to 30 years. Additionally, it is dissolved by solvents commonly used to clean the surface of paintings and/or to remove varnishes - which means if a painting with damar is restored at some point, the restoration might dissolve and lift underlying paint layers. The use of damar in painting mediums is discouraged by conservators.

This isn't to say don't use damar - no painting lasts forever, and every artist is free to choose his or her medium and working method. I just want to be sure you are aware of the drawbacks of damar so you can knowingly choose its pros and cons.

I make an egg oil emulsion that is just yolk and sun thickened linseed, no resin added. It's very simple, takes less than a minute to make: Measure out a tablespoon of extracted egg yolk into a small bowl. Using a small whisk, vigorously blend in a bit less than a tablespoon of a drying oil until you have something akin to hollandaise sauce. Combine this medium with equal parts pigment and you are ready to paint. The paint is water soluble (since there is more egg than oil in the mix) and dries pretty quickly (although it underlying layers are still water soluble for several days, until the oil begins to cure and polymerize). I'm not sure if you could follow the Mische technique exactly with this medium, as underlying layers may not be sufficiently cured to layer as often as Mische requires - but it might.

If you can answer some of my initial questions, perhaps it would be possible to solve the riddle of your dissolving layers. Thanks for checking in to the forum.

Koo Schadler

Last edited by Koo Schadler; 01-07-17 at 12:48 AM.
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