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Canvas is an extremely durable Plain weave Cloth used for making , , marquees, , shelters, as a support for oil painting and for other items for which sturdiness is required, as well as in such fashion objects as handbags, electronic device cases, and shoes. It is popularly used by artists as a painting surface, typically stretched across a wooden frame.
Although historically made from hemp, modern canvas is usually made of cotton, linen, or sometimes polyvinyl chloride (PVC). It differs from other heavy cotton fabrics, such as denim, in being plain weave rather than Twill. Canvas comes in two basic types: plain and Cotton duck. The threads in duck canvas are more tightly woven. The term duck comes from the Dutch language word for cloth, doek. In the United States, canvas is classified in two ways: by weight (ounces per square yard) and by a graded number system. The numbers run in reverse of the weight so a number 10 canvas is lighter than number 4.
The word "canvas" is derived from the 13th century Anglo-French canevaz and the Old French canevas. Both may be derivatives of the Vulgar Latin cannapaceus for "made of hemp", originating from the Greek κάνναβις (cannabis).
Panel painting remained more common until the 16th century in Italy and the 17th century in Northern Europe. Andrea Mantegna and Venetian artists were among those leading the change; Venetian sail canvas was readily available and regarded as the best quality.
Canvas is usually stretched across a wooden frame called a Stretcher bar and may be coated with gesso prior to being used to prevent oil paint from coming into direct contact with the canvas fibers which would eventually cause the canvas to decay. A traditional and flexible chalk gesso is composed of lead carbonate and linseed oil, applied over a rabbit skin glue ground; a variation using titanium white pigment and calcium carbonate is rather brittle and susceptible to cracking. As lead paint is poisonous, care has to be taken in using it. Various alternative and more flexible canvas primers are commercially available, the most popular being a synthetic latex paint composed of titanium dioxide and calcium carbonate, bound with a thermo-plastic emulsion.
Many artists have painted onto unprimed canvas, such as Jackson Pollock, Kenneth Noland, Francis Bacon, Helen Frankenthaler, Dan Christensen, Larry Zox, Ronnie Landfield, Color Field painters, Lyrical Abstractionists and others. Staining acrylic paint into the fabric of cotton duck canvas was more benign and less damaging to the fabric of the canvas than the use of oil paint. In 1970, artist Helen Frankenthaler commented about her use of staining:
When I first started doing the stain paintings, I left large areas of canvas unpainted, I think, because the canvas itself acted as forcefully and as positively as paint or line or color. In other words, the very ground was part of the medium, so that instead of thinking of it as background or negative space or an empty spot, that area did not need paint because it had paint next to it. The thing was to decide where to leave it and where to fill it and where to say this doesn't need another line or another pail of colors. It's saying it in space.De Antonio, Emile. Painters Painting, a Candid History of The Modern Art Scene 1940–1970, p. 82, Abbeville Press 1984,
Early canvas was made of linen, a sturdy brownish fabric of considerable strength. Linen is particularly suitable for the use of oil paint. In the early 20th century, cotton canvas, often referred to as "cotton duck", came into use. Linen is composed of higher quality material, and remains popular with many professional artists, especially those who work with oil paint. Cotton duck, which stretches more fully and has an even, mechanical weave, offers a more economical alternative. The advent of acrylic paint has greatly increased the popularity and use of cotton duck canvas. Linen and cotton derive from two entirely different plants, the flax plant and the cotton plant, respectively.
Gessoed canvases on stretchers are also available. They are available in a variety of weights: light-weight is about or ; medium-weight is about or ; heavy-weight is about or . They are prepared with two or three coats of gesso and are ready for use straight away. Artists desiring greater control of their painting surface may add a coat or two of their preferred gesso. Professional artists who wish to work on canvas may prepare their own canvas in the traditional manner.
One of the most outstanding differences between modern painting techniques and those of the Flanders and Netherlands Masters is in the preparation of the canvas. "Modern" techniques take advantage of both the canvas texture as well as those of the paint itself. Renaissance masters took extreme measures to ensure that none of the texture of the canvas came through. This required a painstaking, months-long process of layering the raw canvas with (usually) lead-white paint, then polishing the surface, and then repeating. The final product had little resemblance to fabric, but instead had a glossy, enamel-like finish.
With a properly prepared canvas, the painter will find that each subsequent layer of color glides on in a "buttery" manner, and that with the proper consistency of application (fat over lean technique), a painting entirely devoid of can be achieved. A warm iron is applied over a piece of wet cotton to flatten the wrinkles.
Canvas can also be printed on using Offset printing or specialist digital printers to create canvas prints. This process of digital inkjet printing is popularly referred to as Giclée. After printing, the canvas can be wrapped around a stretcher and displayed.
Stapled canvases stay stretched tighter over a longer period of time, but are more difficult to re-stretch when the need arises.
Canvas boards are made of canvas stretched over and glued to a Paperboard backing, and sealed on the backside. The canvas is typically linen primed for a certain type of paint. They are primarily used by artists for quick studies.
Art conservators have recently adopted a new method called zero-span strength analysis, nanoindentation, and numerical modelling to quantitatively evaluate the mechanical properties of painting canvases. Zero-span strength analysis measures the tensile strength of materials, such as paper and yarns, by reducing the clamping distance to 0.1 mm and applying load to a particular point on the yarn. This minimizes effects from material geometry and accurately assesses intrinsic fiber strength. This also reduces the amount of material needed for samples to 60 mm. Using zero-span strength analysis, conservators measured tensile strength of flax, commonly used canvas material in historical paintings and correlated tensile strength to the degree of cellulose depolymerization -- cellulose is a component of flax. Another method for assessing canvas quality is nanoindentation utilizing a millimeter-sized cantilever with a microsphere at its end and measuring local Viscoelasticity. However, with the nanoindentation method, conservators can probe the composite behavior of the layers of paint on top of the canvas, not the actual strength of the canvas itself. Lastly, conservators are using finite element modeling (FEM) and extended-FEM (XFEM) on canvases undergoing desiccation (removal of moisture) to visualize the global and local stresses.
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