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More on the materials of the masters ...

From Virgil Elliott

Published before 2005


Kevin Combes wrote:
Mr. Virgil Elliott's technical article concerning the use of sizing and grounds raised a couple of questions for me.

1) He recommends using acrylic matte medium diluted with water as a sizing. How is using this any different from using acrylic "gesso", which is an acrylic emulsion?

2) He says to allow alkyd based primers to dry in an out building due to solvent vapors. Does this hold true for all oil paint used in the execution of a painting?

Thank you. Love the web site, by the way!

Kevin,

1) Sizing is only intended to soak into the fibers of the canvas in order to render it non-absorbent, so it will not draw the binding oil out of the ground layer. The sizing, properly done, does not produce a layer or film. Acrylic "gesso," however, DOES produce a layer, since it is actually a paint, composed of pigment and binder. Its chemical dissimilarity to oil paint limits it to a mechanical bond only, whereas an oil or alkyd ground creates a chemical as well as mechanical bond with oil paint. That being said, I have been informed by my conservator sources that diluted acrylic GLOSS medium is actually a better choice for sizing than acrylic matte medium, as it is less porous. PVA (polyvinyl acetate) is perhaps the best choice of all. Gamblin's PVA Size is already diluted to the right degree, and is also buffered to neutral pH, so it is ready to use right out of the bottle. That is what I use and recommend for sizing, based on recommendations from the conservation department of the National Gallery of Art, in Washington, D.C., and the Smithsonian Institute Museum Support Center.

2) The solvent in alkyd grounds is harmful to the health if one breathes too much of it, and it is not deodorized, so it is nearly impossible to ignore or tolerate anyway. That's why I recommend using it in an outbuilding where the canvas can be left to dry without contaminating the air in anyone's living space. Indeed, all of the solvents commonly used in oil painting are toxic/harmful to the health to one degree or another, and inhalation of their vapors should be avoided as much as possible.

In my studio, I do not have open containers of solvent or any medium that contains solvent while I or my students paint. Linseed oil is the medium, and safflower oil is what is used for cleaning brushes while working, with a rag or paper towels to wipe off the excess oil from the brush when changing colors. I use different brushes for different colors, so I don't have to waste time cleaning brushes while I'm painting, but most of my students have fewer brushes than I do, so they sometimes need to clean a brush to use it for a new color.

After the day's painting session is over, I suspend my brushes in a can of safflower oil, which will keep the paint from drying on the brushes. I have a large coffee can with a plastic snap-on lid to cover it, and I poke holes in the lid to hold the brush handles, inserted from the underside far enough to keep the bristles from touching the bottom of the can with the lid in place. The level of the safflower oil (regular grocery-store safflower oil) is about two inches, so it covers the bristles of the brushes. The next painting session, I just wipe the brushes off with a paper towel, and they're ready to use. Or I can choose to clean them with solvent, outdoors, if I won't be using them for awhile, and then follow that with soap and water and let them dry overnight, hanging with the bristles down. The soap-and-water wash can actually take place right after the safflower oil rinse, for that matter, without any turpentine or turpenoid needed at all. So you see that it is possible to paint in oils without contaminating the air with solvents. There is some indication that Rembrandt followed this approximate practice, though with linseed or walnut oil instead of safflower.

I hope that helps.

Virgil Elliott