Iron is gilt by heating it blue, and laying on the gold-leaf, burnishing, and heating. Repeat till perfect.
Copper buttons are gilt by putting them in nitric acid, and then burnishing on hard stone. Then stir them in nitric solution of mercury till white. The amalgam of gold is then mixed with nitric acid, and the buttons being well stirred the gold attaches. By heating, the mercury is made to run, when, after trituration in a hairy bag, further heat evaporates it, and the buttons are bur nished.
Gilding in cornices, &e., is effected priming with boiled linseed-oil, and car bonate of lead. The surface is then co vered with gold size, on which slips of gold-leaf are pressed with cotton. The edges are then brushed off. Burnished gilding requires priming with gum, and bole must be mixed with the gold size.
Gilding in oil.-1. The first operation is to give a priming coat of color, formed by white lead in oil, rendered drying by boiling with litharge, and tem pered afterwards with linseed-oil, adding a little fat oil, and- a very small portion of spirits of turpentine. 2. Grind cal cined white lead very fine in fat oil ; this must immediately be tempered with oil of turpentine, as it is subject to become thick very quickly. Three or four thin coats of this are to be given very evenly in the ornaments, and in all parts in tended to be gilt. Care must be taken in applying the color to the deeper parts of the work, that it may be even and perfect.—This is the teinte dare, or hard ground. 3. The gold color or size, pre viously strained through fine linen, is then to be laid on, very thin and even, with a soft brush which has been used for oil colors. A smaller brush must be used for the deeper parts of the sculp tuted or other ornaments, carefully ob serving to remove any hairs which may be detached from the brash. 4. Where the size is so far dried as to become tacky, the gold leaf is to be spread upon the cushion, and divided with the knife ; the gold is placed on with a small block of wood, faced with cloth, called a •pa lette, and lightly pressed with cotton, repairing where necessary with pieces of gold cut small, applied by a badger's hair-pencil. 5. If the articles gilt are to be exposed to the weather, as balconies, gratings, statues, &c., they ought not to be varnished, as gilding in oil is more durable without than with varnish. The heat of the sun will, after a heavy rain, cause gilding covered with varnish to craze or crack over its whole surface. Gilding in the interior of a building, as on the rails of staircases, &c., should have a coat of spirit of wine varnish, drying it by means of a chafing-dish, then ap plying a coat of oil varnish. The beauty of oil-gilding depends greatly upon the manner of varnishing it.
For gilding metal baltot:rt.—To 4 oz. of yellow melted bees'-wax add, in fine powder, 1* oz. of •red ochre, 11 oz. of verdigris, calcined till it yields no fumes, and* oz. of calcined borax, and mix them
well. It is necessary to calcine the ver digris.
To exalt the color of green gold.—Take saltpetre 1 oz. 10 dwts., sal-ammoniac 1 oz. 4 dwts., and verdigris 18 dwts., and dissolve a portion of the mixture in water, as occasion requires.
To exalt Me color of yellow gold.—Take saltpetre B oz., green copperas 2 oz., white vitriol and alum, of each 1 oz. If the color be wanted redder, a small portion of blue vitriol must be added. To be dissolved in water, as wanted.
These two last compositions must be applied to the surfaces of the gilt works, either with a pencil, or by dipping them ; a proper degree of heat must then be used to cause them to assume a black color, when they must be quenched, or cooled, either in vinegar or water.
Gilding japan-work is performed with japanner's gold size 7 and for dead gold it should be used with turpentine only, but for lustre with flit oil only.
Gilding earthenware and porcelain.— Take 2 drs. or 5 dwts. of pare gold and triturate in a porcelain mortar carefully, until very fine ; add, at distinct times, 1, 2, and 8 dwts. of pure mercury, and mix well together ; then add 10 grs. of white oxide of lead. Or, exclude the lead, and 1 dwt. of the mercury, when a strong body of gold is required.
On a glass plate, long, and very care fully grind for use.
When the gold (as on some occasions) contains an alloy of silver, less mercury must be taken, and lead wholly ex cluded.
In executing the superior specimens of this art, men are employed ; and in many of the porcelain manufactories may be seen specimens of the high excellence of which it is susceptible, in flowers, landscapes, and portraits. Other less delicate patterns are the work of young women ; of whom, great numbers pro vide for their comforts by these employ ments.
When the gilded ware has been through the muffle, and is cool, the gold is bur nished with nate or bloodstone; the ware is then wrapped in tissue paper, and carefully packed for home, or foreign markets.
On some of the least valuable porce lain, leaf-gold is fixed by being placed on a warm size, formed of these compo nents. Boil together half a pint of pure linseed-oil, oz. of gum arable, gum ben zoin, and acetate of lead severally ; and after being well boiled, cool ; lay evenly on the ware, heat the whole a little, add the strips of leaf-gold, and carefully place for sale.
Pb gild with burnished gold.—Give five or six coats of size and whiting. First with varnish of Armenian bole, wax and size. Wet with water, and lay on the gold, and in a few hours burnish with agate.
To gild the edges of books. — Wash them, in the press, with Armenian bole, sugar candy, and white of eggs. Wet with water and lay on the gold leaf, and burnish with a dog's tooth or steel tooth.
Golden articles of jewelry.—The two best mixtures for the purpose of giving a good gold color to articles of jewelry, are as follows :—