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Question asked 2020-11-12 11:04:40 ...
Most recent comment 2020-11-17 13:54:29
Paint Making
Hi,
every now and then, when I am making my own oilpaint, the paint gets too stringy. I'll add some Omyalite and/or some beeswax dissilved in oil, but that seems to help only a little.
What an I doing wrong? Is it perhaps the not-premium linseed oil? Is Omyalite not the right thickener?
Thanks in advance
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Moderator Answer
(brian baade)
You are doing nothing wrong. Each pigment will create a
different “feel” and rheological effect when made into a paste. In fact, some
will not really make a paste at all, they will remain fluid until the point where
so much pigment has been added that it is unworkable and underbound. I generally
appreciate these differences and exploit them to create certain effects.
Another neat thing is to use paints containing stabilizers/thickeners to create
some effects and paints without these additives to create others. Rembrandt’s
paintings would look vastly different if his lead white was not ropey (what you
call stringy).
Anyway, that is not the thrust of your question. I have not
used Omyalite, but since it appears to be a extremely fine calcium carbonate,
it should work. I would caution against adding it in great quantities creating an
underbound paint film.
The old DYI way to avoid this is to grind your pigments into
linseed oil that has 2% or less of beeswax gently melted into it. This is
generally thought to be below the point where the beeswax could contribute solubility
to the paint. I have avoided this. A more modern method would be to pre-gel your
oil by carefully mulling a small amount of aluminum stearate into your oil before
mulling the pigment into the mixture. I have also done this after the fact by mulling
the AS in very small amounts into already made, overly runny paints.
Perhaps others have thoughts on this.
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Moderator Answer
(george o'hanlon)
As Brian wrote stringiness is a factor related to the chenical and physical interaction of the pigment and binder. Adding aluminum stearate to the oil prior to grinding the oil with pigment will mitigate this effect to large degree, but then you will have the consequences of this additive in your painting. You may also try using a different extender pigment, instead of fine particle chalk, such as mica, which tends to eliminate stringiness with some pigments.
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Moderator Answer
(mkinsey)
The optimal amount has been determined to be 2% by weight (of oil) to improve pigment suspension, stabilize loose oil and avoid perceptible dilution of color. https://cool.culturalheritage.org/waac/wn/wn23/wn23-3/wn23-304.html
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