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then rubbed on, taking care that the projecting parts receive more of the powder than the cavities, to imitate the brightness on those parts of bronze which are liable to be rubbed.
Soldering is the art of joining two pieces of metal together, by heating them with a thin piece or plate of metal interposed between them. Thus tin is a solder for lead; brass, gold, or silver, are sol. ders for iron, &c.
To make Silver Solder.
Melt fine silver two parts, brass one part; do not keep them long in fusion, lést the brass fly off in fumes.
Another for coarser Silver. Melt four parts of fine silver, and three of brass; throw in a little borax, and pour it out as soon as it is melted.
A Solder for Gold. Melt copper one part, fine silver one part, and gold two parts ; add a little borax when it is just melted, then pour it out immediately.
The Method of soldering Gold or Silver. After the solder is cast into an ingot, it would be more ready for use if your were to draw it into small wire, or flat it between two rollers; after that cut it into little bits ; then join your work together with fine soft iron-wire; and with a camel's-hair percil, dipt in borax finely powdered and well moistened with water, touch the joint intended to be
soldered; placing a little solder upon the joint, apply it upon a large piece of charcoal, and, with a blow-pipe and lamp, blow upon it the flame until it melts the solder.
To cleanse Silver or Gold after it is soldered.
Make the silver red hot, and let it cool; then boil it in alum-water, in an earthen vessel, and it will be as clean as when new. If gold, boil it in urine and sal ammoniac.
A Solder for Lead., Put two parts lead to one part tin: its goodness is tried by melting it, and pouring the size of a crown-piece upon the table; if it be good, there will arise little bright stars in it. Apply resin when you use this solder.
A Solder for Tin. Take four parts of pewter, one of tin, and one of bismuth ; melt them together, and run them into narrow thin lengths.
A Solder for Iron. Nothing here is necessary, but good tough brass, with borax applied, mixed with water to the consistence of paste.
MOULDING AND CASTING.
The art of taking casts or impressions from pieces of sculpture, medals, &c. is of very great importance in the fine arts.
In order to procure a copy or cast from any figure, bust, medal, &c. it is necessary to obtain a mould by pressing upon the thing to be moulded or copied, some substance which, when soft, is capable of being forced into all the cavities or hollows of the sculpture. When this mould is dry and hard, some substance is poured into it, which will fill all the cavities of the mould, and represent the form of the original from which the mould was taken.
The particular manner of moulding depends upon the form of the subject to be worked upon. When there are no projecting parts but such as form a right or a greater angle with the principal surface of the body, nothing more is required than to cover it over with the substance of which the mould is to be formed, taking care to press it well into all the cavities of the original, and to take it off clean, and without bending.
The substances used for moulding are various, according to the nature and situation of the sculpture. If it may be laid horizontally, and will bear to be oiled withoutinjury, plaster of Paris may be advantageously employed; which may be poured over it to a convenient thickness, after oiling it, to prevent the plaster from sticking. A composition of beeswax, resin, and pitch, may also be used; which will be a very desirable mould, if many casts are to be taken from it. But if the situation of the sculpture be perpendicular, so that nothing can be poured upon it, then clay, or some similar substance, must be used. The best kind of clay for this purpose is that used by the sculptors for making their models with; it must be worked to a due consistence, and having spread it out to a size sufficient to cover all the surface, it must be sprinkled over with whiting,
to prevent it from adhering to the original. Beeswax and dough, or the crumb of new bread, may also be used for moulding some small subjects,
When there are under cuttings in the bas relief, they must be first filled up before it can be moulded, otherwise the mould could not be got off. When the casts are taken afterwards, these places must be worked out with a proper tool,
When the model, or original subject, is of a round form, or projects so much that it cannot be moulded in this manner, the mould must be divided into several parts; and it is frequently necessary to cast several parts separately, and afterwards to join them together. In this case, the plaster must be tempered with water to such a consistence, that it may be worked like soft paste, and must be laid on with some convenient instrument, compressing it so as to make it adapt itself to all parts of the surface. When the model is so covered to a convenient thickness, the whole must be left at rest till the plaster is set and firm, so as to bear dividing without falling to pieces, or being liable to be put out of its form by any slight violence; and it must then be divided into pieces, in order to its being taken off from the model, by cutting it with a knife with a very thin blade; and being divided, must be cautiously taken off, and kept till dry: but it must be observed, before the separation of the parts be made, to notch them across the joints, or lines of division, at proper distances, that they may with ease and certainty be properly put together again. The art of properly dividing the moulds, in order to make them separate from the model, requires more dexterity and skill than any other thing in the art of casting, and does not admit of rules for the most advantageous conduct of it in every case. Where the sub
ject is of a round or spheroidal form, it is best to divide the mould into three parts, which will then easily come off from the model; and the same will hold good of a cylinder, or any regular curve figure.
The mould being thus formed and dry, and the parts put together, it must be first oiled, and placed in such a position that the hollow may lie upwards, and then filled with plaster mixed with water; and when the cast is perfectly set and dry, it must be taken out of the mould, and repaired when necessary, which finishes the operation.
In larger masses, where there would otherwise be a great thickness of the plaster, a core may be put within the mould, in order to produce a hollow in the cast, which both saves the expense of the plaster, and renders the cast lighter.
In the same manner, figures, busts, &c. may be cast of lead, or any other metal in the moulds of plaster or clay; taking care, however, that the moulds be perfectly dry; for should there be any moisture, the sudden heat of the metal would convert it into vapour, which would produce an explosion by its expansion, and blow the melted metal about.
To take a Cast in Metal from any small Animal,
Insect, or Vegetable.
Prepare a box of four boards, sufficiently large to hold the animal, in which it must be suspended by a string; and the legs, wings, &c. of the animal, or the tendrils, leaves, &c. of the vegetable, must be separated, and adjusted in their right position by a pair of small pincers. A due quantity of