A New Medium

The Merode Altarpiece
(1425-28, The Master of Flémalle, or Robert Campin?)

                    If we compare the Merode Annunciation with those of earlier panel paintings, we see vividly that, all other differences aside, its distinctive tonality makes the Master of Flémalle's picture stand out among the rest. The jewel-like brightness of the older works, their patterns of brilliant hues and lavish use of gold, have given way to a color scheme far less decorative but much more flexible and differentiated. The subdued tints—muted greens, bluish or brownish grays—show a new subtlety, and the scale of intermediate shades is smoother and has a wider range. All these effects are essential to the realistic style of the Master of Flémalle; they were made possible by the use of oil, the medium he was among the first to exploit. 

                    The basic technique of medieval panel painting had been tempera, in which the finely ground pigments were mixed (“tempered”) with diluted egg yolk. It produced a thin, tough, quick-drying coat admirably suited to the medieval taste for high-keyed, flat color surfaces. However, in tempera the different tones on the panel cannot be smoothly blended, and the continuous progression of values necessary for three-dimensional effects was difficult to achieve; also, the darks tended to look muddy and undifferentiated. For the Master of Flémalle these were serious drawbacks, which he overcame by substituting oil for the water-and-egg-yolk mixture. In a purely material sense oil was not unfamiliar to medieval artists, but it had been used only for special purposes, such as the coating of stone surfaces or painting on metal. It was the Master of Flémalle and his contemporaries who discovered its artistic possibilities. 

                    Oil, a viscous, slow-drying medium, could produce a vast variety of effects, from thin, translucent films (called “glazes”) to the thickest impasto (that is, a thick layer of creamy, heavy-bodied paint); the tones could also yield a continuous scale of hues, including rich, velvety dark shades previously unknown. Without oil, the Flemish masters' conquest of visible reality would have been much more limited. Thus, from the technical point of view, too, they deserve to be called the “fathers of modern painting,” for oil has been the painter's basic medium ever since. Needless to say, the full range of effects made possible by oil was not discovered all at once, nor by any one man. The Master of Flémalle contributed less than Jan van Eyck, a somewhat younger and very much more famous artist, who was long credited with the actual “invention” of oil painting.

H.W. Janson
“Late Gothic Painting, Sculpture, and the Graphic Arts”
in History of Art

A Man in a Red Turban (Self-Portrait?)
(1433, Jan van Eyck)