IN THE CENTURIES following the disappearance of the great encaustic technique, painting took on those characteristics which have caused It to be called " primitive." Artists, limited in their technical expression by the lack of a pliable medium for their colors., made little progress either in drawing or painting until up possibilities were opened up to them through the discovery, in 1410, Of a new medium by Jan Van Eyck.

    In this period, besides fresco, there were two other techniques known to painters-painting with oil and painting with tempera (which is painting with a medium that had a base of glue diluted with water). Each of these techniques possessed its own peculiar disadvantages.

     Oil Painting, which had been known for a very long time, was both described and condemned at the same time by the monk, Theophilus, who, in the twelfth century, writing in his Schoedula diversarum atrium said: "Take the colors which you wish to use, grind them carefully in oil, without water, and make the mixtures of colors for the figures and the garments, as you have done until now, with water; anti you will paint with their- natural colors, as it pleases you, the animals, the birds and the foliage." This, essentially, is the same process we use today. The colors in tubes that we use are ground in the same manor. But Theophilus added a little later: "Each time that you have to place a color you cannot superimpose another until the first is dry, which for likenesses is to slow and too tedious. In this case it is preferable to use the gum of the cherry tree." The meaning of this statement is clear. The artist was obliged to wait for the drying of his last touch before continuing with his work, because if he painted into the fresh paint his colors would become muddied in mixing, as do the colors used today. The siccative that is added to the pigments today - which is the only modern technique contribution to the technique of Theophilus--does not alter

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