Henley's Twentieth Century Formulas, Recipes and Processes. VariousЧитать онлайн книгу.
The above figures are understood to be by weight.
The gold solders, known in France under the names of soudures au quart (13 1/2 carat), au tiers (12 carat), and au deux (9 carat), are composed of 3, 2, or 1 part of gold respectively, with 1 part of an alloy consisting of two-thirds silver and one-third copper. Gold also forms with aluminum a series of alloys of greatly varying coloration, the most curious of them, composed of 22 parts of aluminum for 88 parts of gold, possessing a pretty purple shade. But all these alloys, of a highly crystalline base, are very brittle and cannot be worked, for which reason their handsome colorings have not yet been capable of being utilized.
Enameling Alloys.
—I. Transparent.—This alloy should possess the property of transmitting rays of light so as to give the highest possible effect to the enamel. The alloy of gold for transparent green should be pale; a red or copper alloy does not do for green enamel, the copper has a tendency to darken the color and thus take away a part of its brilliancy. The following alloy for transparent green possesses about the nearest print, in color, to the enamel—which should represent, as near as possible, the color and brilliancy of the emerald—that can be arrived at:
| ozs. | dwts. | grs. | |
|---|---|---|---|
| Fine gold | 0 | 18 | 8 |
| Fine silver | 0 | 1 | 6 |
| Fine copper | 0 | 0 | 10 |
No borax must be used in the melting of this alloy, it being of a more fusible nature than the ordinary alloy, and will not take so high a heat in enameling.
II. Red Enamel.—The enamel which forms this color being of a higher fusing point, if proper care be not taken, the gold will melt first, and the work become ruined. In the preparation of red enamel, the coloring matter is usually an oxide of gold, and this so raises the temperature at which it melts that, in order to prevent any mishap, the gold to be enameled on should be what is called a 22-carat red, that is, it should contain a preponderance of copper in the alloying mixture so as to raise the fusing point of the gold. The formula is:
| ozs. | dwts. | grs. | |
|---|---|---|---|
| Fine gold | 0 | 18 | 8 |
| Fine silver | 0 | 0 | 10 |
| Fine copper | 0 | 1 | 6 |
Gold-leaf Alloys.
—All gold made into leaf is more or less alloyed. The gold used by the goldbeater is alloyed according to the variety of color required. Fine gold is commonly supposed to be incapable of being reduced to thin leaves. This, however, is not the case, although its use for ordinary purposes is undesirable on account of its greater cost. It also adheres by contact of one leaf with another, thus causing spoiled material and wasted labor; but for work exposed to the weather it is much preferable, as it is more durable and does not tarnish or change color.
The following is a list of the principal classes of leaf recognized and ordinarily prepared by beaters with the proportion of alloy they contain:
| Gold grs. | Silver grs. | Copper grs. | ||
|---|---|---|---|---|
| I. | Red gold | 456–460 | — | 20–24 |
| II. | Pale red | 464 | — | 16 |
| III. | Extra deep | 456 | 12 | 12 |
| IV. | Deep | 444 | 24 | 12 |
| V. | Citron | 440 | 30 | 10 |
| VI. | Yellow | 408 | 72 | — |
| VII. | Pale yellow | 384 | 96 | — |
| VIII. | Lemon | 360 | 120 | — |
| IX. | Green or pale | 312 | 168 | — |
| X. | White | 240 | 240 | — |
Gold-plate Alloys.
—Gold, 92 parts; copper, 8 parts.
II.—Gold, 84 parts; copper, 16 parts.
III.—Gold, 75 parts; copper, 25 parts.
Imitation Gold.
I.—One hundred parts, by weight, of copper of the purest quality; 14 of zinc or tin; 6 of magnesia; 3/6 of sal ammoniac, limestone, and cream of tartar. The copper is first melted, then the magnesia, sal ammoniac, limestone, and cream of tartar in powder are added separately and gradually. The whole mass is kept stirred for a half hour, the zinc or tin being dropped in piece by piece, the {68} stirring being kept up till they melt. Finally the crucible is covered and the mass is kept in fusion 35 minutes and, the same being removed, the metal is poured into molds, and is then ready for use. The alloy thus made is said to be fine-grained, malleable, takes a high polish, and does not easily oxidize.
II.—An invention, patented in Germany, covers a metallic alloy, to take the place of gold, which, even if exposed for some time to the action of ammoniacal and acid vapors, does not oxidize or lose its gold color. It can be rolled and worked like gold and has the appearance of genuine gold without containing the slightest admixture of that metal. The alloy consists of copper and antimony in the approximate ratio of 100 to 6, and is produced by adding to molten copper, as soon as it has reached a certain degree of heat, the said percentage of antimony. When the antimony