Part 198

Russian Green.—

Malachite green 10 parts Enamel yellow 5 parts Majolica white 5 parts Flux No. 8 (see previous formula) 2 parts

Grind only.

Amber.—

Oxide of uranium 1 part Coral flux 8 parts

Grind only.

Gordon Green.—

Yellow U. G. 5 parts Flux No. 8 (see above) 15 parts Malachite green 10 parts

Grind only.

Celadon.—

Enamel light blue 1 part Malachite green 1 part Flux No. 8 (see above) 15 parts

Grind only.

Red Brown.—

Sulphate of iron, fired 1 part Flux No. 8 (see above) 3 parts

Grind only.

Matt Blue.—

Flux No. 8 (see above) 10 1⁠/⁠2 parts Oxide of zinc 5 parts Oxide of cobalt 4 parts

Glost fire, then take

Of above base 1 part Flux No. 8 (see above) 1 1⁠/⁠8 parts

Grind only. {308}

«PREPARATION OF ENAMELS.»

The base of enamel is glass, colored different shades by the addition of metallic oxides mixed and melted with it.

The oxide of cobalt produces blue; red is obtained by the Cassius process. The purple of Cassius, which is one of the most brilliant of colors, is used almost exclusively in enameling and miniature painting; it is produced by adding to a solution of gold chloride a solution of tin chloride mixed with ferric chloride until a green color appears. The oxide of iron and of copper also produces red, but of a less rich tone; chrome produces green, and manganese violet; black is produced by the mixture of these oxides. Antimony and arsenic also enter into the composition of enamels.

Enamels are of two classes—opaque and transparent. The opacity is caused by the presence of tin.

When the mingled glass and oxides have been put in the crucible, this is placed in the furnace, heated to a temperature of 1,832° or 2,200° F. When the mixture becomes fused, it is stirred with a metal rod. Two or three hours are necessary for the operation. The enamel is then poured into water, which divides it into grains, or formed into cakes or masses, which are left to cool.

For applying enamels to metals, gold, silver, or copper, it is necessary to reduce them to powder, which is effected in an agate mortar with the aid of a pestle of the same material. During the operation the enamel ought to be soaked in water.

For dissolving the impurities which may have been formed during the work, a few drops of nitric acid are poured in immediately afterwards, well mixed, and then got rid of by repeated washing with filtered water. This should be carefully done, stirring the enamel powder with a glass rod, in order to keep the particles in suspension.

The powder is allowed to repose at the bottom of the vessel, after making sure by the taste of the water that it does not contain any trace of acid; only then is the enamel ready for use.