GILDING. - The use of gilding on objects, sculptures, and architectural works dates back to the remotest antiquity.
The most primitive operation was that of covering objects with exceedingly thin sheets of gold; only later did the use of leaf gilding, simpler and less costly, come into practice. The mordant or fixing agent varied according to the material to be covered. For metal, a mercury amalgam applied by fire was used; for marble, egg white; and for wood, a rudimentary varnish called leucophorum. In medieval and modern art, as is known from the sources (Teofilo, Schedula diversorum artium; Cennini, Il libro dell'arte, and Cellini and Vasari), the application of gilding did not differ greatly from that of antiquity.
It was especially employed by painters, who prepared the grounds of their panels in gold; by woodcarvers, who gilded frames, tabernacles, and other ecclesiastical furnishings; and by sculptors, who thus finished many of their bronze works. A remarkable example is provided by the bronze doors of Ghiberti for the Florentine Baptistery, as has recently been confirmed by their cleaning.