Page:The American Cyclopædia (1879) Volume VI.djvu/599

 ENAMELLING In in use. The use of lead must be care- y avoided in articles of this kind. Vessels wrought iron are also treated by the same process ; and iron pipe for conveying water is advantageously protected by a clean silicious enamel not liable to affect the purity of the water. The process employed for many years by the Messrs. Clarke of England consisted in the use of the following composition and method: 100 Ibs. of calcined ground flints and 50 Ibs. of borax calcined and finely ground, to be mixed, fused, and gradually cooled. Of this, 40 Ibs. are mixed with 5 Ibs. of potters' clay, and ground in water to a pasty mass. The vessel, first thoroughly cleaned, is lined with a coating of this about one sixth of an inch thick, and left for it to harden in a warm room. A new coating is next added, pre- pared from 125 Ibs. of white glass without lead, 25 Ibs. of borax, 20 Ibs. of soda in crys- tals which have been pulverized and fused to- gether, ground, cooled in water, and dried. To 45 Ibs. of this 1 Ib. of soda is added, the whole mixed in hot water, dried and pounded. A portion of it is sifted over the other coating while it is still moist, and dried in a stove at the temperature of boiling water. The vessel is then heated in a stove or muffle till the glaze fuses. It is taken out, more glaze powder is dusted on the glaze already in fusion, and it is again subjected to heat. The Polytechnisches Centralblatt for 1872 recommends the follow- ing enamel for copper cooking vessels: 12 parts of white fluor spar, 12 of gypsum, and 1 of borax, finely powdered, and fused in a crucible ; when cold the mass is again pulver- ized, and made into a paste with water, laid upon the metal, and fused. Small articles of enamel, as little toys imitating the figures of birds, &c., and also artificial eyes, are made by melting with the table blowpipe rods or tubes of enamel prepared for this purpose, and shaping them by hand, just as the glass blower works with tubes and rods of glass. Enamel- ling of slates to imitate marble and malachite was introduced in London by Mr. G. E. Mag- nus. The art was first practised in the United States at Boston, and slates from Wales were imported for this purpose. Subsequently the slates of the Lehigh river were applied to this use in Lehigh co., Pa., and were also sent to Philadelphia to be there enamelled. In Ver- mont the business is now carried on at West Castleton, where are extensive quarries of slate, and an establishment of the same kind is in operation in New York. A great variety of useful articles are produced, among which the most important are billiard tables, mantels, tubs for bathing, sinks, &c. The slates are sawed to proper shape, planed to uniform thickness, and rubbed smooth with polishing stones. The ground color adapted to the mar- ble it is designed to imitate is then laid on, and after this the variegated colors. The slab is then placed in an oven heated to 200, and allowed to remain over night. In the morning 294 VOL. vi. 38 ENCAUSTIC 591 after cooling it receives a coat of varnish, and is returned to the oven till the next day. Other heatings and varnishings alternately succeed, with rubbing with pumice stone; and a final polishing with pumice stone, rotten stone, and the hand completes the process. ENCAUSTIC (Gr. /, in, and Kawm/5j, burn- ing), a term applied to the method of fixing colors upon objects by burning them in. En- amelling in colors is an encaustic process. The word is most commonly used in its application to an ancient method of painting, in which wax was employed with the colors, and a coating of the same material was finally applied to the pic- ture to preserve it from the action of the atmo- sphere and light. In modern use a peculiar kind of tiles are called encaustic ; and by the French the same epithet is applied to prepara- tions of wax used for polishing and protecting the surface of wood. The little that is known of the ancient art of encaustic painting is de- rived from the mention made of it by Pliny (" Natural History," lib. xxxv. ch. xi.), Mar- cianus (lib. xvii.), and Julius Paulus (lib. vii. et seq.). M. Bachelier, author of a treatise De Vhistoire et du secret de la peinture en cire, produced a picture in wax in 1749. In 1829 M. de Montabert, in his Traite de tons les genres de peinture, favorably noticed the pro- cess, and M. Durozier of Paris soon after an- nounced that he had perfectly succeeded with the method given by Montabert. The ancient methods appear to have consisted in the use of wax crayons, in which the colors were em- bodied, and which were used upon a heated surface, the outline of the picture having been first traced. The whole was afterward cov- ered with a varnish of wax melted in and pol- ished. The method of Count Caylus consisted of rubbing and melting wax into the canvas or panel, then coating the surface with Spanish white, and painting upon this with water col- ors. By warming the picture the colors are absorbed into the wax, and thus protected. Mr. J. H. Muntz recommends waxing only one side of the canvas, painting on the other in water colors, and then melting the wax through to fix them. ENCAUSTIC TILES consist of a body of red clay, faced with a finer clay, which bears the ornamental pattern, and strengthened at the base with a thin layer of a clay different from the body, which prevents warping. The clay of the body is exposed to the weather for six months or more, and is afterward thorough- ly worked over and tempered, and mixed with other substances, and at last evaporated at the slip-kiln. From a cubical block of this, formed in the usual method by slapping, a square slab is cut off with a wire, upon which slab the fa- cing of finer clay colored to the desired tint is batted out and slapped down; a backing is then applied in the same way to the other side of the tile. It is then covered with a piece of felt, and put into a box press j a plaster of Paris slab containing the pattern in relief is then brought down upon the. fa.ee of the tile,