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Old 17-10-17, 04:00 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 Lora,

Thanks for the clarification regarding "grinding" with a muller; i.e. that you've successfully smoothed pigment particles using a roughened slab and muller. You have a lot more experience in that regard than I have. I imagine it is very exciting to make pigment from old jewelry!

Still, it's important to distinguish between grinding/pulverizing versus dispersing/milling, and that the vast majority of commercially purchased pigments do not need grinding beyond what the manufacturer already has done - although, to your point, if a painter buys an earth pigment that feels too gritty, it's good to know that a muller and slab is sufficient to smooth the rough edges.

All oil and egg tempera paintings eventually develop, with age, a fine craquleure pattern - a result of polymers in the paint film shrinking and losing elasticity, and of stresses in the support. So fine cracks are inevitable (given enough time) - but not desirable, as they invite humidity into the paint film and are the beginning stages of potential delamination. If a painter is interested in longevity in a painting, cracks are definitely to be avoided in the short term (when a painting is first made) and, to the extent possible, delayed in the long term (by making strong paint films, not subjecting a painting to solvents that can leech out fats and decrease elasticity, placing a painting on a stable support, etc).

Why you're getting cracking in pooled paint, I'm not sure. A guess is that the paint is too thick there, and/or the components of the paint have separated out and there too much or too little yolk in those areas. Not the end of the world...then again, not ideal either.

Koo

Last edited by Koo Schadler; 17-10-17 at 06:03 PM.
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