A Select Collection of Valuable and Curious Arts and Interesting Experiments, / Which are Well Explained and Warranted Genuine and may be Performed Easily, Safely, and at Little Expense.

by Unknown

2. The art of burnish gilding.—Make a sizing by boiling the skins of beaver and musk rats, (which may be readily procured at a hat manufactory,) in water, till it is of sufficient strength that by cooling it will become a stiff jelly; strain the liquor while warm, and give your work one coat of it with a brush; when this is dry, add a little fine whiting to the sizing, and give the work one coat of this. Then add as much whiting as will work freely under the brush, and lay on five or six coats of this, allowing each a sufficient time to dry. Smooth the work by wetting it, and rubbing it with a piece of pumice stone, which should be previously cut and fitted to the moulding or other work that is to be gilt; afterward, when the work is dry, rub it with some fine sand paper. Then take some burnish-gold-size (which is composed of pipe-clay, plumbago, beef tallow and castile soap, but may be easily procured ready made,) and dilute it with water till it is of the consistence of very soft putty, and afterward with the above mentioned sizing till it will flow freely from a brush, and give the work three successive coats of this; when the last is dry, dip a camel-hair pencil in a mixture of equal quantities of rum and water, and with it wet a small part of the work, and immediately, while it is flowing, lay on a leaf of gold, brushing it down with a very soft, flat camel-hair brush, with which also, the leaf is usually conveyed from the book to the sizing; proceed thus till the whole is gilt, and let it dry. When the work is sufficiently dry to take a fair polish by burnishing, (which can be only ascertained by applying the burnisher to different parts of the work occasionally while it is drying,) rub over the whole carefully with a flint burnisher, or with the tooth of a wolf or dog, being fixed in a convenient handle, till the whole acquires a brilliant polish, except such parts as are required to remain in a rough-gilt state, which parts are usually flatted by a coat of thin sizing. Such are the principal rules of the art of burnish gilding; but as this business requires some variation of management, according to the state of the weather and other circumstances, it may not be expected that any person should become very expert in the art, without the advantage of some experience and practice.

3. Ornamental bronze gilding.—This is performed by means of gold or silver, reduced to an impalpable powder, called bronze. One method of preparing it, is to levigate any quantity of gold or silver leaves on a stone, with some clarified honey; dilute the honey with clear water, that the bronze may settle; pour off the water and honey, and add fresh water to the bronze, which, after being thus thoroughly washed, may be dried on paper, and is ready for use. Another method of preparing the gold bronze, is to precipitate the gold from its solution in nitro-muriatic acid, (see 5,) by adding sulphate of iron to the solution;—then washing it, as directed above. But in general it will be found much cheaper to buy the bronze ready prepared. The ground for this work must be varnished with a mixture of copal varnish, with an equal quantity of old linseed oil; and whatever figures are to be formed in bronzing, must be represented by holes cut through pieces of paper. Lay these patterns on the work, when the varnish is so dry as to be but slightly adhesive, but not press them down any more than is requisite to keep the paper in its place. Then take a piece of soft glove-leather, moisten it a little by breathing on it, and dip it in some dry bronze, and apply it to the figures, beginning at the edges;—tap the figure gently with the leather, and the bronze will stick to the varnish according to the pattern. Thus any figure may be produced in a variety of shades, by applying the bronze more freely to some parts of the work than to others. If some internal parts of the figures require to be more distinct than others, they may be wrought by their peculiar patterns, or may be edged with dark coloured paint. In some work it may be well to extend the varnish no farther than the intended figures, in which case, any projecting or branching parts of the figures, may be drawn with a camel-hair pencil, and the patterns may in some measure be dispensed with. In either case, the work must afterwards have one or more coats of copal or shellac varnish.

4. To enamel picture glasses with gold.—The glass must first be washed perfectly clean and dried; then damp it by breathing on it, or wet it with the tongue, and immediately lay on a leaf of gold, and brush it down smooth. When this is dry, draw any letters or flowers on the gold with Brunswick blacking, (see 51) and when dry, the superfluous gold may be brushed off with cotton, leaving the figures entire. Afterward the whole may be covered with blacking, or painted in any colour, while the gold figures will appear to advantage on the opposite side of the glass. This work may be elegantly shaded by scratching through the gold with a small steel instrument, (in the end of which many sharp points are formed,) previous to laying on the blacking. Oil paints of any kind may be substituted in the place of the blacking, but will not dry so quick.

5. To wash iron or steel with gold.—Mix together in a phial, one part of nitric acid, with two parts of muriatic acid, and add as much fine gold as the acid will dissolve. For this purpose gold leaf is the most convenient, as it will be the most readily dissolved. (This solution is called the nitro-muriate of gold.) Pour over this solution, cautiously, about half as much sulphuric ether;—shake the mixture, and then allow it to settle. The ether will take the gold from the acid, and will separate itself from it also, and form an upper stratum in the phial. Carefully pour off this auriferous ether into another phial, and cork it close. Wash any piece of steel or iron with this ether, and immediately plunge it in cold water, and it will have acquired a coat of pure gold. With this also, any flowers or letters may be drawn or written, even with a pen, and will appear perfectly gilt. The steel or iron should afterward be heated as much as it will bear without changing colour, and if the steel be previously polished, the beauty of the gilding may be much increased by burnishing with a cornelian or blood stone.

6. To wash brass or copper with silver.—To half an ounce of nitric acid in a phial, add one ounce of water, and one fourth of an ounce of good silver. It will soon be dissolved, and if the acid and metal are both pure, the solution, (which is called nitrate of silver) will be transparent and colourless. Add to this a solution of nearly two drachms of muriate of soda, in any quantity of water; this will precipitate the silver in a white opaque mass. Pour off the water with the acid, and add to the silver an equal quantity of super-tartrate of potass, thus forming a soft paste;—dip a piece of soft leather in his paste, and rub it on the metal to be silvered; continue rubbing it till it is nearly dry; then wash it with water, and polish by rubbing it hard with a piece of dry leather. Another method is, to add sub-carbonate of potass to the nitrate of silver, as long as ebulition ensues; then the acid is poured off, and the precipitate, (which is white at first, but becomes green when dry,) is mixed with double its quantity of muriate of soda, and super-tartrate of potass. With this composition, being moistened, the metal is rubbed over, &c.