2396. Dead-White Enamel

2396.    Dead-White Enamel. For white enamel, the articles must be perfectly free from foreign admixture, as this would impart a color. When well managed, either of the following forms will produce a paste that will rival the opal. Calcine (from 2 parts of tin and 1 part of lead calcined together), 1 part; fine crystal or frit, 2 parts; a very trifling quantity of manganese; powder, mix, melt, and pour the fused mass into clean water; dry, powder, and again fuse, and repeat the whole process 3 or 4 times, observing to avoid contamination with smoke, dirt, or oxide of iron.

2397. Fine White Enamel

2397.    Fine White Enamel. Washed diaphoretic antimony, 1 part; fine glass (perfectly free from lead), 3 parts; mix, and proceed as before.

2398. To Make Black Enamel for Gold or Silver

2398.    To Make Black Enamel for Gold or Silver. Melt together in a crucible, 1 part, by weight, of silver, 5 parts copper, 7 parts lead, and 5 parts muriate of ammonia. Add to this mixture twice its quantity of pulverized sulphur, covering the crucible immediately. Let it calcine until the excess of sulphur has passed off. Then pound the compound to coarse powder and make it into a paste with a solution of muriate of ammonia. This is the black enamel used for jewelry.

2399. To Black Enamel Gold or Silver

2399.    To Black Enamel Gold or Silver. Place some of the enamel paste, as prepared in the preceding receipt, on the article to be enameled; hold it over a spirit lamp until the enamel melts and flows upon it. It may then be smoothed and polished.

2400. Black or Enameled Copper

2400. Black or Enameled Copper. The beautiful enameled surface possessed by paintings on copper, may be produced, on "a black ground, by the following process: Clean the copper with sand and sulphuric acid, and then apply the following mixture: 2 parts white arsenic, 4 parts hydrochloric acid, 1 sulphuric acid, and 24 water.

2401. Enamel for Labels, Signboards, etc

2401.   Enamel for Labels, Signboards, etc. The fine enamels of trade are generally prepared by fusing at high temperatures, silica, oxide of tin, and oxide of lead, and spreading the mixture over the surface of a sheet of copper, gold, or platinum. The objections to the'se enamels are, in the first place their high cost, and secondly the impossibility of giving them a perfectly flat surface. Mr. E. Duchemin has advantageously replaced them by the following economical and efficient compound:

2402. Duchemin's Enamel for Labels, etc

2402.   Duchemin's Enamel for Labels, etc. Arsenic, 30 parts by weight; saltpetre, 30 parts; silica (fine sand),90 parts; litharge, 250 parts. This is spread on plates of glass of the required shape and size, care being taken, however, that the kind of glass employed be not inferior in point of fusibility to the enamel. Enameled glass prepared from the above substances may be drawn or written on as readily as if it were paper, and in less time than one minute the writing may be rendered indelible by simply heating the plate in a small open furnace or muffle. Drawings, autographs, legal acts, public documents, historical facts and dates of importance, labels for horticultural purposes or destined for out-of-door exposure, coffin plates, signboards, show-case signs, etc., may thus be cheaply made, which will resist atmospheric influences for ages. First-class photographs, either positives or negatives, may be taken on such enamels without collodion. (See Photographs on Enamel.)

2403. Enamel for Iron Hollow Ware

2403.    Enamel for Iron Hollow Ware. The enamel of iron hollow ware is made of powdered flints, ground with calcined borax, fine clay, and a little feldspar. This mixture is made into a paste with water and brushed over the pots after they have been scoured with diluted sulphuric acid and rinsed clean with water. While still moist they are dusted over with a glaze composed of feldspar, carbonate of sodium, borax, and a little oxide of tin. Thus prepared, the pots are gradually dried and then the glaze is fired or fused under a muffle at a bright red heat. Oxide of lead, although increasing the fusibility of the glaze, impairs its efficiency, as it will not resist the action of acids in cooking.