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according to the current usage of the time, but whether the heat of the sun was too great or the wood was not sufficiently seasoned, the panel came apart in all its joints.
"When this disaster occurred, Jan formed a resolution to find some method whereby his pictures would never again be in danger of attack by the sun. He began to look for the formula of a varnish that would dry in the shade, and that would no longer necessitate the exposure of his paintings to heat. He made many experiments, and at last found that linseed and walnut oil were the most siccative among all of those he tried. After boiling them with other ingredients, he achieved a varnish that not only himself but all the other painters as well had been anxious to find. "His paintings, especially when they were still new, had the penetrating odor which this oil, mixed with colors gave off; and he thought that his secret would be discovered; but for many years it was not. "When he grew old at last, he favored his pupil, Roger van der Weyden by initiating him into the secret, and Roger passed it on, in his turn. .. ." Further along, Vasari speaks of the resistance of Van Eyck's paintings to water. Speaking of the portrait of King Alphonso of Naples, he wrote, "a painting which could be washed and still remain perfect. ,, It is examples such as these that have aided in the reconstruction of the medium of Van Eyck, but before we proceed further, let us see what were the inadequacies of the protecting varnish used until his time. The formula for a varnish given by Theophilus that was transcribed by Merimee many centuries later, reads as follows: "Place in a new glazed pot, a third Part of gum vernix* and two-thirds of linseed oil, and heat until the total volume is reduced by a third." It is probable that this varnish Theophilus speaks of had a basis of amber, since very few of the copals that we use today had been discovered before 1410. Amber makes a very thick varnish, for it will mix with oil only at a high temperature which causes it to thicken, reducing and transforming the oil into a barely liquid paste. Before spreading it on the canvas it was * A gum of unknown origin. |