by Jane Sutherland

Mounting Linen on Masonite

I have always used cotton canvas for my oil paintings, but I would now like to start using linen. Can I mount the primed linen on Masonite as I have done with cotton canvas, or does it need to be stretched?

Primed linen canvas can be mounted onto Masonite in the same manner as cotton canvas. Oil-primed canvas is more flexible than acrylic-primed canvas, which is an advantage if you intend to wrap the edges of the canvas around the panel. The best adhesive is hide glue. Hide glue is easy to use and apply, and if there is ever a need for restorative treatment the canvas can be removed from the panel. The disadvantage of hide glue is its vulnerability to moisture penetration, which can cause the canvas to loosen from the support. Acrylic emulsion gel or acrylic gloss medium are good adhesives that are not prone to moisture penetration, but these glues are more permanent.

Working With Powdered Charcoal

I am about to start several medium-to-large (30"-x-40") charcoal drawings and want to use powdered charcoal. Do you have any recommendations for how to apply and use it?

You can apply powdered charcoal with blending tools such as cotton balls, bristle brushes, mop-style brushes, blending stumps, chamois cloths, Q-tips, or any other such material. For erasing charcoal powder, a kneaded eraser will take off some of the charcoal pigment, and a pink pearl or vinyl eraser removes most or all of the pigment in much the same way as it does with charcoal pencils or sticks. Another method of using powdered charcoal is to put some ordinary household rubbing alcohol on a cotton cloth and rub the cloth over the charcoal on the paper, which produces a lovely steel-gray tone. Because charcoal powder can spread into the air during applications, it is advisable to wear a mask when working with it over an extended period of time. Be practical and lay out only as much powder as you need to achieve the desired effect.

Oil-Primed Canvas and Acrylic-Primed Canvas

What is the difference between oil-primed canvas and acrylic-primed canvas? I recently bought some prepared canvas and once I got home I felt it was too smooth. Is there any way to rough it up a bit?

The surfaces of these primed coatings feel slightly different. Oil-primed canvas is more flexible than acrylic-primed canvas, which tends to be brittle by comparison. Oil paint can be used on both oil-primed canvas and acrylic- and alkyd-primed canvas, but acrylic paint should not be used on oil-primed canvas.
There are significant differences in preparing oil-primed and acrylic-primed canvas. An oil-primed canvas first receives a coat of glue size and then one or two coats of oil paint. The glue size forms a protective layer between the oil ground (primer) and the support, preventing the ground from penetrating the canvas. White lead, the long-established ground, is no longer used in priming canvas because of the health hazard associated with lead paint. Titanium white, zinc white, and oil-priming white are all satisfactory alternatives. Hide glue, long used for sizing, is sensitive to humidity, which can cause the canvas to lose its shape. Today hide glue can be replaced with synthetic glue.

Acrylic emulsion gesso primer has been available since the 1960s. Although acrylic gesso can be applied directly to the support without a size, it is advisable to apply a coat of acrylic medium to size the fabric before priming. Otherwise the ground may go through the fabric and form beads on the back side of the canvas, which can cause the front side to appear irregular. Acrylic gesso should not be used over hide glue. Because acrylic primer has less body than oil primer, it may be necessary to apply as many as three or four coats of primer depending on the weave of the canvas and whether or not you want the weave of the fabric to be perceptible.

The advantages of acrylic primer are its rapid drying time (12 to 24 hours), and simple cleanup (no solvents are necessary, just soap and water). Oil primer, on the other hand, takes up to two weeks to dry. Alkyd, another primer alternative, does require a glue size but will dry overnight so that a second coat can be applied. However, a two-week drying period, although not necessary with alkyd primer, is recommended to increase the stability of the canvas.

You can give some tooth to the surface of a smooth canvas by working either a pumice stone or a piece of very fine sandpaper evenly and gently across the entire canvas. A sandpaper block (a rubber holder made to be wrapped with sandpaper) is useful if you choose to work with sandpaper.

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