works of art age. Light, atmospheric conditions, microbes, and pollutants can cause some pigments to darken and others to fade, varnish to yellow, paint to flake, paper to develop blotches, canvas to rot, wood to crack, marble to decompose, bronze to suffer corrosion, and dirt, dust, and grime to work their way into just about everything. As a final irony, our very presence—the moisture of our breath, the warmth of our bodies, the oils left from a casual touch—can pose a danger to the works of art we so admire.
Conservation aims to slow the inevitable effects of time by keeping works of art in the safest possible conditions. It is one of the most important tasks of museums, where it is the job of highly trained specialists. Museums take many steps to prolong the life of objects in their care. Vulnerable objects are displayed in glass cases, where temperature and humidity can be carefully controlled. Works on paper are exhibited at low light-levels, and paintings are kept away from direct sunlight (and camera flashes). Each object is examined regularly for signs of deterioration.
For larger works outside museum settings, public access may need to be limited. Since 1963, for example, the famous Lascaux caves (see 14.1) have been closed to all but five visitors per day, five days a week. (Tourists are directed to a nearby replica of the caves.) The Arena Chapel, whose walls boast an important cycle of frescoes by Giotto (see 15.26), has recently been placed in a sort of “iron lung”—a closed, air-conditioned environment that purifies the air inside the chapel and continuously monitors its atmosphere. Visitors are permitted in groups of twenty-five, and they may remain for only fifteen minutes. In between groups, the chapel “rests” for fifteen minutes so that its microclimate can restabilize.
Occasionally, the decision is taken to clean or restore a work in an attempt to roll back the effects of time. The decision can be controversial. In the past, techniques used for cleaning and restoration have sometimes done more harm than good. Even today, with methods informed by the latest scientific findings, heated debates about what technique to use, or even whether to proceed at all, are not uncommon.
Among the most highly publicized of recent conservation projects was the restoration of Leonardo's Last Supper, a detail of which is shown here. In painting the mural, Leonardo had experimented with a new technique of his own devising. The results began to deteriorate not long after he finished. Over the centuries, a series of well-intentioned but heavy-handed restorations left experts wondering what, if anything, was left of Leonardo's original work. Beginning in 1977, a team of restorers under the direction of Dr. Pinan Brambilla Barcilon labored for over twenty years to determine which flecks of paint remained from Leonardo's hand and to remove everything else. Areas where nothing was left at all were filled in with pale, removable watercolor that lessens the visual shock of the absence while being clearly distinguishable from the original pigment. What remains is a more luminous but far more fragmentary image than we had before. Our only comfort is that at least it is all by Leonardo.