Many artists today consider oil painting to be the fundamental art medium; something that a student should learn to appreciate, because of its properties and use in previous, very popular artwork. Typical qualities of oil paint include a long "open time," which means that the paint does not dry quickly. Oil paints take several weeks to dry, this allows the artist to work on a painting for many sessions. Oil paint also has a propensity to blend into surrounding paint allowing very subtle blending of colors. This medium also produced vivid color with a natural sheen and distinct contrast. Oil paints have a surface translucency similar to human skin, making it an ideal medium for portraits.
The color of oil paint derives from the small particles mixed with the carrier. Common pigment types include mineral salts such as white oxides: lead, now most often replaced by less toxic zinc and titanium, and the red to yellow cadmium pigments. Another class consists of earth types, e.g. sienna or umber. Synthetic pigments are also now available. Natural pigments have the advantage of being well understood through centuries of use but synthetics have greatly increased the spectrum available, and many are tested well for their lightfastness.