Understanding Canvas and Linen
by Christopher Willard

New Orleans Conservation Guild
THE GUILD IN THE PRESS
American Artist September 2003

When deciding whether to paint on canvas or linen, artists can solicit advice from two authorities: conservators and other artists. Here, Blake Vonder Haarm he director of the New Orleans Conservation Guild, and portraitist Duffy Sheridan of Eloy, Arizona, offer their opinions.

THE CONSERVATOR'S VIEW

Vonder Haar points out that the word canvas is often used generically to refer to any stretched support. She is quick to clarify this misnomer, explaining that only canvas is woven using fibers from the fruit of the cotton plant. The number of ounces of cotton used in a yard of material determines the weight of the canvas. Canvas that artists consider thin has a weight of around seven ounces and is often labeled "single fill." Medium-weight canvas is about 10 ounces and is often called "cotton duck." Heavy canvas can weigh 14 to 20 ounces. Medium- to heavyweight canvases may also be labeled "double fill," referring to the fact that two threads are twisted together to make a single stronger thread.

"An artist does not need to know specific numbers to purchase appropriate canvas," Vonder Haar says. "It's more important to touch and feel the weight. Most canvas weights fall between a scale that would have a thin bedsheet on one end and an extra heavy sailcloth on the other. Exactly which weight artists artists need depends on their method of painting."

An artist who paints thinly can use a lighter-weight canvas with no technical problems, but according to Vonder Haar, an artist who applies thick impasto should buy a heavier-weight canvas, citing Portrait of William W. Rhett as a worst-case scenario. "The portrait was only 2 years old when I restored it because the simple rule of applying thick paint to heavy canvas had been broken," she relates. "The portrait was heavily painted on a light-weight canvas. The cotton canvas was not heavy enough to support the thick paint, and the sheer weight of the paint caused the canvas to start sagging. Canvas normally expands and contracts with changes in humidity. The keysin the corners of the stretcher frame are there to tighten the canvas if it starts to sag. But in this case, the corners of the stretcher bar were glued, and there were no keys. So first the canvas sagged, then the paint started cracking, and some of the paint actually flaked off." Vonder Haar notes that if the artist had employed the correct weight of canvas for the thick paint and used a professional stretcher frame with corner keys, the need for restoration so early in the painting's life would not have been necessary.

Another option is linen, which is made from the flax plant. "It has a natural brownish color, and it is also classified by weight," Vonder Haar explains. Linen is more durable than cotton, it's less prone to shrinkage, and it has a bit more spring to it. Many artists enjoy linen's slightly oily feel (flax is also the plant from which linseed oil is produced). Because the fibers of linen are longer than those of cotton, there are more varieties of linen than canvas, from the ultra-fine weaves of portrait linen to a fabric of super-coarse texture. Linen is more expensive than canvas and is therefore better suited for the professional than the student. For an artist concerned with long-term archival durability, linen is a better choice because it is less prone to degradation.

"Whether buying canvas of linen, artists should also look at the consistency of the weave," says Vonder Haar. "They should examine the entire run of the canvas they wish to purchase for seams or flaws, such as large bumps or fat threads that run through it." She adds that the weight of a fabric does not correlate with the texture—that is, "heavier canvas isnot necessarily bumpier," she says.

From an archival point of view, Vonder Haar says it makes no difference if an artist uses a preprimed or unprimed canvas or linen, provided that he or she uses a proper ground. "Preprimed canvases are so well-prepared," she remarks. Linen and canvas can be primed with either acrylic or oil grounds, and artists should check when buying either fabric. The conservator also notes that artists should cut rather than tear their fabric. "Tearing," she says, "can stretch and stress the weave."

Vonder Haar encourages artists to experiment with many varieties of canvas and linen. Once an artist finds the perfect support, she suggests buying it by the rool, which can be less expensive. In the conservation studio, she hangs the rolls of canvas and linen, rather than standing them up on end. "This prevents the canvas or linen from stretching, and it keeps it clean," she says. "It also prevents annoying wrinkles that would be just one more thing to deal with when stretching." The tube can be fed onto a horizontal pole or suspended by a rope through the center. Artists who purchase a few yards of unrolled fabric can find cardboard rools at a carpet-supply store. Finally, Vonder Haar recommends that artists "store canvas and linen so air can sirculate around it, and keep it out of direct sunlight, which can fade, shrink, or degrade the fabrics."

THE ARTIST'S VIEW

Sheridan painted on canvas for 15 years, but lately, he works primarily on fine portrait linen. "When working on canvas, I always tried to find a weave as perfect as possible, and the tightness of the weave was never as important as the consistency," he recalls. "I demand a consistently smooth surface, not glasslike but one my sable brushes will slide over easily. The integrity of my surface is important because I don't pile on globs of paint."

Sheridan's first priority when buying canvas was to inspect the fabric. He explains, "One or two inconsistent strands can create a line or series of bumps that detract from a portrait. I really couldn't have that. The imperfections always seemed to show up in the most inconvenient places, such as the eyeball or the face of the portrait."

He eventually switched to portrait linen of a very high quality because "it reveals no visual flaws, and it takes the paint perfectly," he says. There are many varieties of linen, and Sheridan judges them by touch. He then buys six-yard rolls at a width of 56 inches. He prefers preprimed linen, finding single-primed easier to work with than double-primed. Although the artist has learned to apply a ground to a solid weave of canvas and achieve the same results, he still favors Belgian portrait linen, "because I've used it for so long," he says.

Linen does present some dificulties. "Linen is less flexible than canvas because it has a tighter weave," Sheridan points out. "It's also harder to stretch than canvas, and even after it's stretched, linen will have unnecessary wrinkles." His solution is to dampen the fabric with water and then restretch while the material is wet. After it dries completely, he gives the surface what he calls, "a shot of my own primer."

Each portrait requires more than 450 hours of work, so Sheridan demands reliability from his support. He says, "Most paintings present an artist with problems—that is normal. But the last thing I want is an unreliable surface. Someone could give me a thousand-dollar-a-yard linen, but if it doesn't feel right, if I find it unreliable, then it's no good for me."