The phrase "rectangular canvas" refers to a flat piece of material that has four straight sides and four right angles, similar to a sheet of paper. It is often used as a surface for painting or drawing. Full definition
In the early 1960s, he moved away from the traditional rectangular canvas, extending his paintings into the three - dimensional space. (patchoguearts.org)
In the 1950s and 1960s Stella's interest in the idea of art as an object rather than as a symbolic representation was reflected in his series of Black Paintings, which were rectangular canvases painted in black stripes with thin lines of unpainted canvas, and his Irregular Polygon series, which was painted on irregularly shaped canvases. (mmoca.org)
Through a single medium — vitreous enamel spray paint — on rectangular canvases and free standing or wallmounted foam - core boards, Rhodes will present an installation of paintings in Gallery III. (caseykaplangallery.com)