PART III.
Of gilding, lilvering, bronzing, ja- paning, laquering, and the ftaining different kinds of fubftances, with all the variety of colours.
CHAP. I.
Of gilding.
SECT. I. Of gilding in general.
THE gilding different fubftances is per-formed by a variety of means accom-modated to the nature of each : but the principle is the fame in all} (except with refpedt to one kind pradtifed on metals, where quickfilver or heat is ufed, which I omit here as not properly a part of the fubjedt of this work j) being only the putting fome proper cement on the body to be gilt} and then lay-ing the gold either in the form of leaves, or powder, on the cement; which binds it to the body.
The principal kinds of gilding are thofe called oil gilding varnifh gilding j—and japanners gilding or gilding with gold fize. Thefe may be promil'cuoufly ufed on grounds either of wood, metal, or any other firm and rigid body: but paper and leather require a treatment in fome cafes peculiar to them- felves.
The firft attention, in moft kinds of gilding, is the choice of leaf gold : which fhould be pure, and of the colour accommodated to the purpofe, or tafte, of the work. Purity is requifite in all cafes : for if the gold be allayed with filver it will be of too pale and greenifh a hue for any application; and if it contain much copper, it will in time turn to a yet much ftron- ger green. The purity may be afcertained with accuracy enough for this purpofe, by the touch- ftone, and aqua fortis; and the fitnefs of the Colour, to any particular purpofe, may be diftinguifhed by the eye. The full yellow is certainly the moft beautiful and trueft colour of gold: but the deep reddifh caft has been of late moftefteemed from the caprice of fafhion: which ever may be chofen, die colour ought neverthelefs to be good of the kind j for there is a great variation in the force and effect of different parcels of the fame teint; fome appearing more foul and muddy; others bright and clear.
The beft method however of judging of the colour of leaf gold with nicety, is by keeping a fpecimen of fuch as is perfect j with which any frelh parcel may be occafionally compared.
There is, befides the true leaf gold, another kind in ufe, called Dutch gold : which is copper gilt and beaten into leaves like the genuine. It is much cheaper j and has when good greatly the effeft of the true at the time of its being laid on the ground; but, with any accefs of moifture, it lofes its colour, and turns green in fpots; and, indeed, in all cafes, its beauty is foon impaired, unlefs well fecured by laquer or varnifh. It is neverthelefs ferviceable for coarfer gilding, where Urge maffes are wanted; efpe- ally where it is to be feen by artificial light as in the cafe of theatres: and if well varnifhed will there in a great meafure anfwerthe end of the genuine kinds.
The other preparations of gold, belonging to particular kinds of gilding, I fhall treat of them, as likewife the cements or other fub- ftances employed, in their refpettive places j and proceed now to fhew, what the inftru- ments are, which are common to the three principal methods.