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Question asked 2017-11-23 19:22:07 ...
Most recent comment 2017-11-26 21:00:27
Grounds / Priming
Greetings MITRA folks. Can you tell me if oil painting directly on a shellaced panel is an accepted and durable practice? I know of at least one company which sell panels that have been "sanded and shellaced on both both sides and edges with a wax-free shellac," and they are advertised as a "ready-to-use painting support." I know of both acrylic and oil painters who use these particular panels, but I do not know if they are adding an oil or acrylic ground over the shellaced surface before proceeding with oils. Knowing only of shellac from a furniture sort of standpoint, I would have thought that shellac as a surface for oil paints *directly* would be too slippery and would have poor long-term adhesion. Would you kindly set me straight on this subject? Thank you!
Answers and Comments
First, shellac would not be my first choice for a size for
wooden panels but it should be perfectly serviceable. It does benefit from
being delivered in a non-aqueous solvent. This means that the wood will not
have its grain raised or issues of warping caused by the application of a
shellac size. A size should never be applied so thickly as to create a discrete
layer and certainly not a glossy surface. Any size applied too thickly will
cause problems with adhesion (actually this is less of an issue when painting
acrylic dispersion colors on acrylic dispersion grounds since the acrylic dispersion
binder is such a good adhesive as compared to oil paint) . See our section on
sizes in our “Resources” section for general issues about sizing.
If the shellac is applied in a dilute enough state that is
cuts and evens out the absorbency of the panel but does not create a discrete layer
which would eliminate mechanical adhesion of the ground and paint layers, this
should be a trustworthy panel. Whether these specific panels are “acceptable
and durable” would relate to the above as well as what type of panels they are
sealing with shellac. No size is likely to make a junk panel acceptable.
There is actually a long history of the use of shellac as a
preliminary application before oil paint in the house painting trade. I seem to
remember reading a house painting manual from the early 20th century
where it said to, “give the wall a good drink of shellac before painting in oil
paint,” or something to that effect. I just checked and R. Mayer also mentions
Now, the above is specifically about the use of such a size under an oil ground
and oil paint. I can see no reason to use a shellac-sized wooden panel for
subsequent acrylic dispersion grounds and paint. In that case, it would make
more sense to size the panel with acrylic dispersion medium or perhaps PVA
size. Animal glue, if one choses to use it despite its reactivity to the
environment, should only be used under oil and alkyd layers.
There should be no problem in terms of paint adhesion/etc
for you to paint directly on the shellac sized panel. The only issue would be
the color of the panel. Depending on how dark the wood is, this would be
visually similar to painting on a mid-toned or even dark colored ground. We
know from examining old oil paintings that oil paint can becomes more transparent
overtime. This is mostly, but not completely, the result of a chemical change
in lead white and even zinc white paints. Thinly painted lighter or even
mid-valued paints can become darker because of this increased transparency.
This sometimes resulted in an exaggerated contrast effect where the darks
became slightly darker, the midtones disappeared, and the thickly applied
highlights remained light. Othertimes, it caused an overall lowing of the value
and intensity of the painting.
We are not sure if paintings made with titanium white will
exhibit this increased transparency of time but it is unlikely to do so to the
same degree. We now know that oil painters should avoid the use of zinc white
for a number of reason. I am also definitely not suggesting that oil painters should
avoid lead white. It is really the best oil paint that we have in terms of
preservation. Additionally, there are plenty of paintings from the 17th-21th
C. where that artist left portions of their wooden panel exposed for a specific
effect. We just do not know the degree to which these have shifted overtime. What
I am suggesting is that a painting executed on a darker color (like could be
the case with shellac sized wood) should not be painted too thin if the artist
wants to avoid possible changes overtime.
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