SILVERING

is the art of covering the surfaces of bodies with a thin film of silver. When silver leaf is to be applied, the methods prescribed for gold leaf are suitable. Among the metals, copper or bra are those on which the silverer most commonly operates. Iron is seldom silvered; but the proce es for both metals are e entially the same. The principal steps of this operation are the following :— 1. The smoothing down the sharp edges, and polishing the surface of the copper; called émorfiler by the French artists. 2. The annealing ; or, making the piece to be silvered redhot, and then plunging it in very dilute nitric acid, till it be bright and clean. 3. Pumicing ; or, clearing up the surface with pumice-stone and water. 4. The warming , to such a degree merely as, when it touches water, it may make a slight hi ing sound; in which state it is dipped in the very weak aquafortis, whereby it acquires minute insensible asperities, sufficient to retain the silver leaves that are to be applied. 5. The hatching . When these small asperities are inadequate for giving due solidity to the silvering, the plane surfaces must be hatched all over with a graving tool; but the chased surfaces need not be touched. 6. The bluing , consists in heating the piece till its copper or bra colour changes to blue. In heating, they are placed in hot tools made of iron, called mandrins in France. 7. The charging , the workman’s term for silvering. This operation consists in placing the silver leaves on the heated piece, and fixing them to its surface by burnishers of steel, of various forms. The workman begins by applying the leaves double. Should any part darken in the heating, it must be cleared up by the scratch-brush. The silverer always works two pieces at once; so that he may heat the one, while burnishing the other. After applying two silver leaves, he must heat up the piece to the same degree as at first, and he then fixes on with the burnisher four additional leaves of silver; and he goes on charging in the same way, 4 or 6 leaves at a time, till he has applied, one over another, 30, 40, 50, or 60 leaves, according to the desired solidity of the silvering. He then burnishes down with great pre ure and addre , till he has given the surface a uniform silvery aspect.