The oldest Mediterranean civilization, Greek, Roman or Egyptian have extensively used painting techniques based on mixtures of encaustic (probably rich in bee wax), mineral pigments (iron, copper, manganese oxides) and tempera. Vegetal oils, such as flax, walnut or poppy seed oil were known to ancient Egyptians, Greeks or Romans, but no precise indication of their use in painting may be found. Tempera is a fluid mixture of binder (organic medium), water and volatile additives (vegetal essential oils). Organic binders used by Italian artists were pertinacious materials available from animal sources (whole egg, animal glues or milk).

At the end of the Roman Empire and up to the Renaissance period (15th century), this ancient technique was lost and replaced by oil paint and/or tempera. In Italy and Greece, olive oil was used to prepare pigment mixtures but the drying time was excessively long and tedious in the case of figures. This drawback led a German monk, Theophilus, in the 12th century to warn against paint recipes including olive oil (Schoedula Diversarum Artium). It was reported that Aetius Amidenus, a medical writer in the 5th century, mentioned the use of a drying oil as a varnish on paintings. Similarly, it seems that perilla oil was used in Japan in painting after addition of lead in the 8th century. In the 14th century, Cennino Cennini presented a painting procedure integrating tempera painting covered by light oily layers.

 

According to Giorgio Vasari (1511-1574) in his "Lives of the Artists" (Le vite de piu eccelenti pittori, scultori e architetori, Firenze, 1550), the technique of oil painting, as used till now with few technical modifications, was invented or re-invented in Europe around 1410 by Jan van Eyck (1390 -1441). In fact, as said before, this Flemish painter was not the first to use oil paint; his real achievement was the development of a stable varnish based on a siccative oil (mainly linseed oil) as the binder of mineral pigments. It could be established that the Van Eyck secret was a mixture of piled glass, calcined bones and mineral pigments in linseed oil maintained a long time up to a viscous state at boiling temperature. Besides linseed oil, walnut oil and poppy-seed oil were also used while not so quick-drying. It is probable that painters have already observed that these oils led to accelerated drying time of canvas under the sun. It seems that Van Eyck kept his secret up to about 1440, a few time before his death.

 

Historians agree that the masterpiece of Van Eyck, the wedding portrait of Giovanni Arnolfini and his wife (National Gallery, London) painted in 1434, is one of the first and the best example of the new technique. If the pigments were the same as those used by Italian painters, the siccative oil has increased brilliance, translucence and intensity of color as the pigments were suspended in a layer of oil that also trapped light. The resulting optical effect obtained with pigment-oil mixtures and stacked layers explain the enameled aspect of Van Eyck works. These innovations in the oil medium produced an art that set the standard for a long time and which has never been surpassed.