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Gilding, Silvering, and Tinning (To Gild Glass and Porcelain)

To Gild Glass and Porcelain.

Drinking and other glasses are sometimes gilt on their edges. This is done, either by an adhesive varnish, or by heat. The varnish is prepared by dissolving in boiled linseed-oil an equal weight either of copal or amber. This is to be diluted by a proper quantity of oil of turpentine, so as to be applied as thin as possible to the parts of the glass intended to be gilt. When this is done, which will be in about 24 hours, the glass is to be placed in a stove, till it is so warm as almost to burn the fingers when handled. At this temperature the varnish will become adhesive, and a piece of leafgold, applied in the usual way, will immediately stick. Sweep off the superfluous portions of the leaf; and when quite cold it may be burnished, taking care to interpose a piece of very thin paper (Indian paper) between the gold and the burnisher.

If the varnish is very good, this is the best method of gilding glass, as the gold is thus fixed on more evenly than in any other way.

Another Method.

It often happens, when the varnish is but indifferent, that by repeated washing the gold wears off; on this account the practice of burning it in is sometimes had recourse to.

For this purpose some gold powder is ground with borax, and in this state applied to the clean surface of the glass by a camel's-hair pencil.

When quite dry the glass is put into a stove heated to about the temperature of an annealing oven; the gum burns off, and the borax, by vitrefying, cements the gold with great firmness to the glass, after which it may be burnished. The gilding upon porcelain is in like manner fixed by heat and the use of borax; and this kind of ware being neither transparent nor liable to soften, and thus to be injured in its form, in a low red heat, is free from the risk and injury which the finer and more fusible kinds of glass are apt to sustain from such treatment. Porcelain and other wares may be platinized, silvered, tinned, and bronzed in a similar manner. Preparation for Gilding Porcelain.

This preparation, the invention of the brothers Dutuste, is reported on by Salvétat. The peculiar advantage of it is, that after burning the gold is so bright as not to require polishing. Thirty-two grammes of gold are gently warmed with 128