FADING MASTERPIECES

Sun (Auckland), Volume IV, Issue 1078, 16 September 1930, Page 10

FADING MASTERPIECES

SCIENCE TO AID OF GREAT PICTURES PATIENT RESEARCH WORK The fierce sunlight o£ recent days , gives rise to the thought that never j since the time of the ancient Greeks ; has the light of day been more'thor-j oughly appreciated than it is at the ! present time. We hear more and more of the beneficial effects of sunlight i upon the body. We hear of scientific apparatus by which ultra-violet light j can be artificially produced; we hear | of a special kind of window glass which permits these health-giving rays to reach the children in schools, the workers In factories, the patients in i hospitals and sanatoria, and the ! creatures in zoological gardens. The j time seems definitely to have passed ; when one of the most important busi- I nesses of the housewife was to draw j the blinds in order “to keep the sun- i light out” (writes R. R. Tutlock, in j the “Daily Telegraph”). All this is the result of long anil patient research work on till- part of an army of trained scientists, who have carried out innumerable experiments connected with the study of tlie spectrum of daylight, and the j analysis of various rays, both visible j and, like the ultra-violet and the infrared rays, invisible, and having very j odd and unexpected functions and ; effects.

But if the summer sunshine brings with it health and well-being to human and animal life, it spells danger to | the welfare of many works of art. j The four great enemies of the painted j picture are sunlight, water, a polluted j atmosphere and strong heat. j Water, considered in relation to old j masters, is a most important factor. | An object may lie in a perfectly dry atmosphere for many centuries without undergoing any important psycical i change. Both mummies and works j of art have lain in deserts so free j from moisture that no sign of animal j or vegetabel life is perceivable, and j after the passage of enormous lapses j of time still preserve their most im- : portant characteristics. But take one j of these objects to Europe, and ex- j hibit it in the ordinary manner, and j it will give way at once to decay.

It used to be the custom to wash the surface of old pictures with water, but Sir Charles Holmes proved conclusively that when that is done the water sinks into the cracks in the pigment and sets up a kind of rot. This can be prevented to a large extent by treating the canvas or panel with a species of tan. The effects of polluted air on an old picture are necessarily very various and depend on the kind of foreign bodies to be found in the air. In great industrial centres like Sheffield, Manchester and Glasgow chemicals of one kind or another attack varnish and paint with certain more or less wellascertained effects; and fog has he;n proved to be harmful to old masters, though the damage in that case consists mainly in a mere dulling of the surface. Unless more drastic measures are called for (and that can be determined only by expert examination), a weekly polishing with a silk duster may suffice. The good results from that simple process have been made evident in the case of Leonardo’s “Virgin of the Rocks” at the National Gallery.

Long exposure to powerful daylight tends in most cases to the reduction of intensity of the colours of oil paint.. A famous instance was a painting on canvas by Tintoretto in Venice, a corner of which had been turned back, probably soon after the picture was painted. Not many years ago the corner was re-exposed, and was seen to be many times more vivid in colour than the rest of the'picture; but after a short experience of the daylight it became just as dark and dim as the main part of the picture. Oil paint, however, does not suffer through exposure to strong light anything like as much as water colour does. Some familiar water-colour pigments are so “fugitive” that they ought to be abolished by serious artists. Experiments with water colours have recently been made, with valuable results, at the National Psysical Laboratory, and still more reeently Messrs. .1. A. Macintyre and H. Buckley have developed the work there performed.

Their main conclusions are that in the case of valuable water colour pictures dried air should be supplied by a simple apparatus to the surface of the picture behind its glass, and that ultra-violet light should be excluded. When that was done in the course of the experiment it was found that fading did not take place to any great extent provided no definitely unstable pigments, such as Turner, unfortunately, dabbled with, w-ere used.

In the case of less valuable water colours screening from strong light is recommended This, of course, is already a general though not a universal practice. It comes to this, that water colours deteriorate in sunlight because of the ultra-violet rays contained therein, and in the ordinary air of a temperate climate because of the water contained therein. All preventive measures must be directed to the elimination of these tw 7 o factors.