O il painting developed in Europe in the late Middle Ages. Oil paint dries relatively slowly with little change in colour.
Tones are therefore easy to match, blend, or grade, and corrections are easy to make.
Without being restricted to a pre-arranged design, the painter can freely change and improvise. Most artists today use commercial materials but some prefer to make their own paints in the traditional way. Oil paint consists of ground pigment mixed with oil that dries on exposure to air. The pigments, or coloured powders, must be insoluble, impervious to fading, and chemically inert. The oil is usually linseed but may be poppy or walnut.