Artists' colors made by grinding pigment in linseed oil or another vegetable oil to a smooth paste-like consistency. Other ingredients include a drier, a stabilizer and plasticizer such as wax to give each color the same consistency. Since the 15th century in Europe, oil paint has been the most traditional medium for fine-art painters because it, unlike the prevalent tempera, was more amenable to the depiction of flowing robes for church and political dignitaries. Artists of the late Middle Ages and early Renaissance combined oil with tempera such as in the work of Piero della Francesca (c. 1420-1469) and Filippo Lippi c. 1406-1469). The Venetian painters increasingly used oil, and Titian (1477-1576) and Tintoretto (1518-1594) used oil primarily for their paintings, although some European artists continued to use oil and tempera together. Reasons for the desirablity of oil paint are that it dries slowly, allowing for changes with the brush, and and does not change colors when it is dry. Also the oil painter can achieve both opaque and transparent effects and matte and gloss finishes. Today a group of western painters called the Oil Painters of America actively promote oil as a medium. Prominent members include Howard Terpning, Roy Andersen, Joan Potter, George Carlson, Clyde Aspevig, David Leffel, Sherrie McGraw, Mian Sditu and Ramon Kelley. Sources: Ralph Mayer, "A Dictionary of Art Terms and Techniques"; AskART biographies. <br><br>Slow drying paint made when pigments are mixed with an oil, linseed oil being most traditional. The oil dries with a hard film, and the brightness of the colors is protected. Oil paints are usually opaque and traditionally used on canvas. They can have a matte, semi-gloss, or glossy finish. To look at examples of works in oil paints, see the articles under the names of every period from the Renaissance onward.Here are examples of particularly early oil paintings:Giovanni Bellini (Italian, c. 1430?1516), Giovanni Emo, c. 1475-83, oil on wood panel, 19 1/4 x 13 7/8 inches (49 x 35 cm), National Gallery of Art, Washington, DC. Giovanni Bellini, St. Francis in the Desert, c. 1480, tempera and oil on wood panel, 49 x 55 7/8 inches (124.4 x 141.9 cm), Frick Collection, NY.Related resources: Chalkboard's article on oil painting. Chalkboard is produced by Ralph Larmann, a member of the art faculty at the University of Evansville, IN. Also see pellicle, pochade, primer, stain and stain removal, and the names of various oil painting techniques, such as abbozzo, alla prima, impasto, overpainting, and underpainting.