He stated the problem exactly when he placed it in the
domain of the material, and he showed that although a pupil
of the Ecole des Beaux Arts who had won the Grand Prix de
Rome might be capable of copying correctly a work by his
master,he could never successfully attempt the reproduction
of any work of the earlier periods because he did not possess
the exact medium used in those times.
Merimee's researches have given us the formulas for four varnishes. Unfortunately, the use of some of these proved disastrous in actual practice. Prud'hon used one of them on his "Christ on the Cross," in the Louvre Museum, and in view of its present state we cannot but confirm the failure of this particular formula.
As to the modern treatises on the formulas of the old masters, these are little more than interesting compilations of isolated, ancient texts. Because the authors deal here in theory they often contradict themselves to such an extent that the painter today cannot learn from these texts a single exact procedure. In general they tend to indicate what should not be done (and even in this they are often wrong) and they never make a clear statement of what is right to put into actual practice. Their chief value lies in certain quotations that are to be found in them and in the bibliographies they furnish. But they do not, in themselves, offer any practical solution for the artist today, which is the real objective of our studies.
I believe that in order for any discoveries claimed from Researches of this nature to have value they must meet three definite conditions. First, the characteristics of the process sought must be clearly defined and objective evidence of these characteristics must be given. Second, these evidences must be in accord with, or supported by, descriptions or of historical authenticity. Third, a painting executed with the reconstructed medium must show the same charac- teristics as a painting by the master whose technique it attempts to reproduce.
With these considerations in mind, I chose, as the point of departure for my studies, documents whose authenticity I deemed incontrovertible and paintings of unquestionable