Cooley's Cyclopaedia of Practical Receipts Volume I Part 261

The whole is, lastly, carefully polished with tripoli and water.

GILDING, WASH, AMALGAM G., MERCURIAL G., WATER G. This consists in the application of a thin coating of amalgam of gold to the metallic surface (bra.s.s, bronze, or copper) to be gilded, and the subsequent volatilisation of the mercury by heat. It is the usual method of gilding articles of copper and its alloys, and possesses great beauty and durability when skilfully executed. The occupation is, however, an unhealthy one, owing to the continual exposure of the workman to the fumes of mercury. The furnace invented by M. D'Arcet obviates this evil, as the whole of the volatilised mercury is carried off, and again condensed for further use. It should, therefore, be adopted by every water-gilder who studies economy and the health of those in his employ.

The process of water gilding consists in several distinct operations, and can only be successfully performed by those who have been schooled in the art by an apprenticeship to the trade. It would, therefore, be waste of s.p.a.ce to enter into details here. Formulae for several of the articles employed for the purpose will be found in the alphabetical places in this work.

GILDING, WATER. See _above_.

Among the applications of the process of gilding that deserve a separate notice are the following:--

The gold letters and figures on the covers of BOOKS are thus formed:--Gum mastic, in fine powder, is dusted over the surface to be gilded; an iron or bra.s.s tool bearing the design upon its face is then heated to a proper temperature, and gently pressed upon a piece of leaf gold, which slightly adheres to it; the two are then transferred to the cover, and the tool is gently pressed on it, by which means the mastic softens and retains the gold. The loose gold and powdered mastic are then dusted off with a brush.

Gold leaf will adhere to leather without the use of mastic, but not so firmly as when it is employed.

The edges of the leaves of books and paper are first cut perfectly smooth, and then washed over with a solution of isingla.s.s in weak spirit, or with a varnish made of Armenian bole, 4 parts, and powdered sugar-candy, 1 part, mixed up to a proper consistence with strained white of egg. The coating is allowed to dry, and is then smoothed with a wet rag, after which the gold leaf is applied and polished with the burnisher.

BRa.s.s b.u.t.tONS, formerly so much in demand, are covered by a rough species of wash gilding. The b.u.t.tons are polished in the lathe and thrown into a pan with a little amalgam of gold, and as much aquafortis diluted with water as will wet them all over. Here they are well stirred up, until they a.s.sume a silvery appearance, when they are washed with clean water. They are then submitted to a sufficient heat in a suitable apparatus, until the mercury is volatilised. The b.u.t.tons are next cooled, and well tossed and rubbed about with a painter's brush; and are, lastly, burnished by washing them well with beer or ale grounds.

Twelve dozen (1 gross) of b.u.t.tons, of 1 inch in diameter, may be perfectly gilded on both sides with only 5 gr. of gold. By an Act of Parliament, which is still unrepealed, this is the smallest quant.i.ty of gold permitted to be used for a gross of b.u.t.tons of the above size.

GLa.s.s, PORCELAIN, and EARTHENWARE, are gilded by blending powdered gold with gum-water and a little borax, and applying the mixture by means of a camel-hair pencil; the article is then heated in an oven or furnace, by which means the gum is burnt, and the borax, vitrifying, cements the gold to the surface. It is afterwards polished with a burnisher. Names, dates, or any fancy device, may thus be permanently and easily fixed on gla.s.s, china, earthenware, &c.

j.a.pANNED WORK is gilded by the method explained as 'j.a.panner's gilding'

(_above_).

LEATHER is gilded in the same way as the covers of books. (See _above_.) For common work, silver leaf, or even tin foil, is applied to the surface, previously covered with size or white of egg, and after being burnished down and dried, is washed over with gold-coloured lacquer.

The LETTERS of sign-boards and the ornamental gilding for out-door work are done by first covering the design with yellow paint, then with oil gold-size, and when this is nearly dry applying the leaf gold, observing to shield it properly from the wind, lest it be blown away or become crumpled before being properly attached. The work is, lastly, varnished.

POLISHED METALS may be gilded by one or other of the methods already noticed. Articles in silver, copper, bra.s.s, and bronze, are usually coated by the process of wash or water gilding; or, directly, by the application of gold leaf, as follows:--The piece or article is heated to a bluish tint, and gold leaf pressed gently and carefully on it with the burnisher; heat is again applied, and the process repeated with fresh leaves of gold until the gilding has acquired the proper thickness and tone. The surface is lastly polished with the burnisher, or is coloured in the usual manner at the stove. This succeeds with iron, steel, silver, copper and its alloys, &c. Another method for polished articles in iron and steel, which, however, is less durable than the preceding, is to apply an ethereal solution of gold to the surface with a camel-hair pencil. The ether flies off and leaves the surface coated with gold, which is then polished as before. In this way, any fancy device or writing may be executed on steel or iron with extreme facility.

SILKS, SATINS, WOOLLENS, IVORY, BONE, &c., may be readily gilded by immersing them in a solution of neutral terchloride of gold (1 of the salt, and 3 to 6 of water), and then exposing them to the action of hydrogen gas. The latter part of the process may readily be performed by pouring some dilute sulphuric acid on zinc or iron filings, in a wide-mouthed bottle, and placing it under a jar or similar vessel, inverted, at the top of which the articles to be gilded are suspended.

Flowers or other ornamental designs may be produced by painting them on the surface with a camel-hair pencil dipped in the solution. The design, after a few minutes' exposure to the hydrogen, shines with all the splendour of the purest gold, and will not tarnish on exposure to the air, or in washing.

GILDED THREAD or GOLD THREAD is merely a thread of yellow silk covered with a very thin flatted wire of gold, by means of a revolving wheel.

WIRE (copper, silver, or bra.s.s) is occasionally gilded, in coils, by a similar process to that adopted for b.u.t.tONS; but more frequently as follows:--Rods (usually of silver) are covered with gold foil of a thickness proportionate to the quality of the intended wire, and the compound bar is then drawn into wire, in the usual way. 100 gr. of gold was formerly the lowest legal quant.i.ty that could be employed for 1 lb. of silver.

_Patents._ Among the varieties of chemical gilding may be mentioned

1. (Elkington's patent--GERMAN GILDING, Bonnet's GILDING PROCESS.) The articles to be gilded, after being perfectly cleaned from scale or grease, and receiving a proper 'face,' are suspended, by means of wires, in the gilding liquid (boiling hot), and moved about therein for a period varying from a few seconds to a minute, or longer; the precise time required depending on the newness and strength of the liquid. When sufficiently gilded, the articles are withdrawn from the 'solution of gold,' washed in clean water, and dried; after which they undergo the usual operation of 'colouring,' &c. A dead gold appearance is produced by the application to the articles of a weak solution of nitrate of mercury previously to the immersion in the gilding liquor; or the deadening may be given by applying a solution of the nitrate to the newly gilded surface, and then expelling the mercury by heat.

The gilding liquor.--Take of fine gold, 5 oz. (troy); nitro-muriatic acid, 52 oz. (avoirdupois); dissolve by heat, and continue the heat until red or yellow vapours cease to be evolved; decant the clear liquid into a suitable vessel; add of distilled water, 4 galls.; pure bicarbonate of pota.s.sa, 20 lbs.; and boil for 2 hours. The nitro-muriatic acid is made with pure nitric acid (sp. gr. 145), 21 oz.; pure muriatic acid (sp. gr.

115), 17 oz.; and distilled water, 14 oz.

This process, though patented by Mr Elkington in England, was in reality discovered and first practised by M. Bonnet, a foreigner. Articles thus gilded do not bear friction and the operations of being put in colour (_mise en couleur_) so well as those gilded by the mercurial process, or by the methods of cold or leaf gilding as applied to polished metals.

2. (Talbot's patent.) By this process polished metallic articles are gilded by simple immersion in a solution of gallic acid in water, ether, or alcohol, to which a solution of gold has been previously added.

SILVERING and PLATINISING may be effected in the same manner, by using a solution of either of these metals instead of one of gold.

? These and other chemical processes have been almost completely superseded by the certain and economical process of ELECTRO-GILDING. See ELECTROTYPE.

=Gilding Amalgam.= See AMALGAM.

=Gilding Liquor.= This name has been given to various solutions of gold, and to other liquids employed in gilding. The former are noticed elsewhere. Among the latter are the following:

DEADING AQUAFORTIS. From mercury, 1 part; aquafortis (sp. gr. 133), 3 parts; dissolve, and add of soft water, 7 parts. Used to produce a dead-gold effect. It is applied (diluted) to the articles, before spreading the amalgam over them, in water gilding; or before placing them in the 'gilding liquor,' in the chemical processes.

MERCURIAL SOLUTION. From mercury, 10 parts, dissolved in aquafortis (sp.

gr. 133), 11 parts, and the solution diluted with 25 times its weight of water. Used to moisten the scratch brush before drawing it over the amalgam, in mercurial gilding; also to deaden the gilded surface, by moistening the latter with it, and then exposing the piece to a heat sufficiently high to drive off the mercury.

GILDER'S PICKLE. From alum and common salt, of each 1 oz.; nitre, 2 oz.; dissolved in water, 1/2 pint. Used to impart a rich colour to gold surfaces, especially of trinkets. Its application should not be too long continued, as it dissolves a small portion of the gold. For common purposes it is best used largely diluted with water.

VERMEIL, VERMEIL COATING, OR-MOLU C. From annotta and salt of tartar, of each 1 oz.; dragon's blood, 1/2 oz.; water, 1 quart; simmer down to about one fourth, add saffron, 20 gr., and when merely tepid, strain through fine muslin into a bottle. Used to give l.u.s.tre and fire to distemper gilding. A little is floated over the surface with a very soft, flat, camel-hair brush.

=Gilding Metal.= The metal employed as a base for gilding is usually bra.s.s, or a mixture of bra.s.s and copper. The following proportions have been recommended:--

1. Copper, 6 parts; bra.s.s, 1 part.

2. Copper, 4 parts; Bristol bra.s.s, 1 part.

3. Copper, 13 parts; old Bristol bra.s.s, 3 parts; tin, 14 parts.

=Gilding Powder.= _Prep._ 1. Pure gold, 5 dr.; pure copper, 1 dr.; aqua regia, 10 oz.; dissolve, moisten clean linen rags with the solution, dry them, and burn them to ashes. The latter contain the gold in a state of minute division, and must be carefully collected.

2. Grain gold, 1 dr.; rose copper, 15 gr.; aqua regia, 2 fl. oz.; proceed as last. Used in 'Gold Gilding.'

3. See Gold (in powder).

=Gilding Sh.e.l.ls.= See GOLD Sh.e.l.lS.

=Gilding Size.= See GOLD SIZE.

=Gilding Wax.= _Syn._ GILDING VARNISH, GILDER'S WAX. _Prep._ 1. From beeswax, 4 oz.; verdigris and sulphate of copper, of each 1 oz.; melted together.

2. Beeswax, 4 oz.; verdigris, red ochre, and alum, of each 1 oz. Used to give a red gold colour to water gilding.

=GIN.= _Syn._ GENE'VA. Corn spirit flavoured with either oil of juniper or oil of turpentine.

Gin was originally and, for some time, wholly imported from Holland, and was a rich, soft spirit, flavoured, chiefly, with juniper berries; on which account it had obtained the name of 'GENEVA,' from 'GENIeVRE,' the French for juniper. After a time the distillation of an imitation geneva sprung up in this country, when the foreign spirit came to be called 'HOLLANDS,' or 'HOLLANDS GENEVA,' to distinguish it from the spirit of home manufacture. The English monosyllable 'GIN' is a corruption of geneva, the primary syllable of which, as in numerous other instances, was seized on by the vulgar, and adopted as a short and convenient subst.i.tute for the whole word.

The liquor at present known by the name of 'gin' in this country is a very different article to that imported from Holland, and consists of plain corn-spirit, flavoured with oil of turpentine and small quant.i.ties of certain aromatics. The thousand and one receipts for this article, which have from time to time been printed in books, produce a flavoured spirit bearing no resemblance to the more esteemed samples of English gin; and, if possible, the products are even more unlike genuine Hollands. Any persons may easily satisfy himself of the truth of this a.s.sertion by actual experiment on the small scale. The cause of this incongruity has arisen chiefly from the writers not being practically acquainted with the subject, and from the disinclination of well-informed practical men to divulge, gratuitously, what they conceive to be valuable secrets. Hence the utter failure of any attempts to produce either gin or Hollands from the receipts usually published. The authors appear to have all imbibed a juniper-berry mania--probably from the imbibition of their favourite beverage. Oil of juniper, in the hands of these gentlemen, appears to be a perfect aqua mirabilis, that readily converts whisky into gin, and imparts the rich creamy flavour of 'Schiedam Hollands' to crude corn or mola.s.ses spirit. But theory and experiment sometimes disagree. In practice, it is found that the true flavour of foreign geneva cannot be imparted to spirit by juniper alone, and that the English gin of the present day depends for its flavour on no such a substance. The following formulae are merely given as specimens; and it is proper to remark, that every distiller has his own receipt for this notorious beverage. Hence it is that the gins of no two distillers are of precisely the same flavour; and this difference is still more marked when the distillers reside in parts of the country remote from each other. Booth's, Smith's, and Nicholson's gins have each a characteristic flavour, readily perceived by their respective votaries; whilst the difference between 'Plymouth' or 'Bristol gin,' and the 'gin of the metropolis,' is as remarkable as that between 'Barclay's x.x.x' and 'Guinness's bottled stout.' These variations in flavour generally depend on the use of more or less flavouring matter, or of a spirit more or less clean or free from taint; and, less frequently, on the addition of a small quant.i.ty of some peculiar aromatic, which exercises a modifying influence on the chief flavouring ingredient. In many cases the flavour has originated from accident, but the consumers having become accustomed to, and hence relishing, that particular 'palate,' it is found to be unwise or commercially impossible to alter it. Any change in these matters is therefore looked upon in every distillery as a dangerous innovation, which would prove more prejudicial to the prosperity of its exchequer than the repeal of the duty on French wines and brandy, or even a frightful conflagration. The distillers, like the brewers, are thorough conservatives in all matters connected with the flavour of their liquors.

In the preparation of gin, both sweetened and unsweetened, and indeed of liquors generally, the greatest possible care must be taken to avoid an excess of flavouring. The most esteemed samples are those that consist of very pure spirit, slightly flavoured.

_Prep._ 1. Clean corn spirit, at proof, 80 galls.; newly rectified oil of turpentine, 1-1/4 pint; mix well by violent agitation, add culinary salt, 14 lbs., dissolved in water, 40 galls.; again well agitate, and distil over 100 galls., or until the faints begin to rise. _Product._ 100 galls.

of gin 22 u. p., besides 2 galls. contained in the faints. If 100 galls.

at 17 u. p. are required, 85 galls. of proof spirit, or its equivalent at any other strength, must be employed.

2. Proof spirit (as above), 8 galls.; oil of turpentine, 1 fl. oz.; salt, 1-1/2 lb., dissolved in water, 4 galls.; draw over 10 galls., as before.

22 u. p.

3. Clean corn spirit, 80 galls.; oil of turpentine, 1 pint; pure oil of juniper, 3 fl. oz.; salt, 21 lbs.; water, 35 galls.; draw over 100 galls., as before. 22 u. p.