GILDING AND BRONZING One of the most ancient of the arts included within the painter's craft is that of gilding, or overlaying a surface with thin sheets of beaten metal—gold, silver, aluminum, tin, etc. The modern decorator uses gilding in many ways, either for accenting mouldings or carvings, as in the Colonial styles; for forming a background on walls; or for exterior ornamentation. It is used for the ornamentation of railroad cars and wagons, and extensively employed in sign work. In some classes of architecture, especially in church decoration, it is often found advisable to employ large surfaces of gold; but in domestic architecture, the pure metal, in large unbroken masses, is ordinarily too garish to suit the culti vated taste, unless it is modified in tone. Gild ing on oak or chestnut wood might be appro priate in an apartment where a very rich effect is desired and where handsome fabric hangings are used on the walls.
Besides gilding with leaf metal, there is an other method of coating a surface with metal, termed bronzing, because the metals usually em ployed are bronzes or alloys, although pure metal is sometimes employed. In this case the metal is used in a powdered form and is made to adhere to the surface, either by being first mixed with some suitable liquid or vehicle and spread upon 153 the surface in the same manner as paint, or else the surface is first coated with paint or with size, and, while the surface is still tacky, the bronze powder is dusted upon the surface. Bronze is cheaper than gold and the labor of ap plying it is much less. However, unless the bronze powder is made from pure gold or alumi num, there is always a tendency to tarnish whereas gold leaf is one of the most durable decorations known, perishing only by abrasion.
Gold Leaf. Gold leaf is still made in the same manner in which it was produced in olden times, nothing so far having been found to super sede the gold-beater's hammer. Gold can be rolled out by machinery to very thin sheets; but the thinnest sheet so produced is many times thicker than the gold leaf that is beaten out by hand, for each sheet of gold leaf averages but one three-hundred-thousandth part of an inch in thickness, and it requires 2,000 sheets three and one-quarter inches square to weight one ounce.
As pure gold is too soft to stand ordinary wear and tear, an alloy of gold and silver or gold and copper, such as is used in the manu facture of jewelry or for coinage, is usually em ployed in making gold leaf. The best commer cial gold leaf is twenty-two carats fine, or, in other words, twenty-two parts of pure gold are alloyed with two parts of harder metal. The color of the leaf varies with the proportion of copper or silver used, from almost silvery white to "red gold." The great advantage which gold leaf pos sesses over all other leaf metals is that it will not tarnish, but will retain its original color and brightness, save as it may be affected by thin films of grime or dirt deposited upon its surface, and it is absolutely unaffected by any of the gases ordinarily contained in the atmosphere.
Gold leaf is sold in "books," each contain ing twenty-five sheets interleaved with paper specially prepared to prevent the gold from ad hering. For exterior work, gold leaf is fur nished closely pressed against white tissue paper to which it firmly adheres. Upon being pressed against the sticky surface of the size, the paper can be pulled away from the gold leaf, which re mains firmly adhering to the surface to be gilded. In this form the gold leaf can he freely handled in the open air without danger of being blown away. This is usually termed patent gold leaf.
old leaf is made extra thick (from two to three times the usual thickness) for use on weather vanes, balls on flag poles, gilded domes, crosses on church steeples, and similar locations where the surface undergoes peculiar exposure and where the work of regilding is attended with unusual difficulty and expense.