Colour Fading in Van Gogh and Gauguin

One is aware that painting materials evolve with time. They take on an appearance which is specific to the pigments and techniques used in the various epochs. The relationship within the tonalities change, and some pigments are subject to environmental influences, especially the effect of light.

Artists of the Gothic period and the Renaissance used colours whose stability had already been ascertained and, thanks to long workshop experience, they chose them in accordance with the medium in which they wished to bind them. They were also aware of their specific properties, for instance their resistance to various ambient influences. The present condition of these paintings testifies to the excellen­ce of the techniques employed by these artists.

At the beginning of the sixteenth century, when the pro­portion of drying oils in the medium gradually increased, materials underwent a new type of aging. This process usu­ally induced darkening. Twentieth-century observers are so accustomed to this darkened appearance that even famous experts, art historians or specialists could be misled as to the artist's true intentions.

This calls to mind the curses pronounced against the restoration of the Sistine Chapel: the darkening of Michelangelo's frescos was not due to any change within the paint material itself, but to the soot and other deposits from the burning of candles and similar sources of pollution not to mention some unfortunate former conservation treatments. This superficial accumulation of grime has given the fresco a misleading appearance similar to that of oil paintings of-the same period. The fresco is still in a good condition, apart from limited losses in the plaster. The freshness of the fresco. colours recovered after the recent cleaning gives one an idea of how bright and luminous contemporary oil paintings must have been .

A other example of colour alteration is illustrated by the Tintoretto fragment of three red apples and green leaves, discovered by chance during the 1905 restoration in the Scuola di San Rocco in Venice. The fragment was part of a frieze with the heraldic arms of the great schools, and putti holding garlands of flowers. and fruit, and had been pro­tected from light and pollution by being folded under another part of the frieze. The colours had remained un­altered, and retained their original intensity.

Reading about painting conservation, one is too often told about paintings that have been brought back to their original freshness, as though they had just come from the artist's studio. This illusion comes from a misunderstanding of the inevitable impact of time on the materials that consti­tute works of art. It is necessary to have a profound knowl­edge of a painter's technique in order to get an idea of his vision at the moment of creation. Equally essential is the historical knowledge concerning the artist's intent, in order to be aware of the chromatic change of his paintings.

Generations of scholars have studied the works of the past, examining arid comparing them, and have arrived at conclusions that are well known to us today. Yet we have far less information about works executed in the last 100 or 150 years, which does not mean that they have been less subject to change. We often wonder, for instance, if certain colours have not faded a phenomenon that is well known in watercolours and tapestries. Jean Leymarie, who studied Van Gogh's oeuvre in depth, mentioned a strong alteration of certain chrome yellows, but to the author's knowledge there has as yet been no specific documentation of such a change of chrome yellow in Van Gogh's work.