Encaustic (Gr. in, and burning), a term applied to the method of fixing colors upon objects by burning them in. Enamelling 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 picture to preserve it from the action of the atmosphere and light. In modern use a peculiar kind of tiles are called encaustic; and by the French the same epithet is applied to preparations of wax used for polishing and protecting the surface of wood. The little that is known of the ancient art of encaustic painting is derived 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 l'histoire et du secret de la peinture en cire, produced a picture in wax in 1749. In 1829 M. de Montabert, in his Traite de tous lea genres de peinture, favorably noticed the process, and M. Durozier of Paris soon after announced 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 embodied, and which were used upon a heated surface, the outline of the picture having been first traced.
The whole was afterward covered with a varnish of wax melted in and polished. 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 colors. 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 thoroughly 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 shipping, a square slab is cut off with a wire, upon which slab the facing 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; a plaster of Paris slab containing the pattern in relief is then brought down upon the face of the tile, and the design is impressed into the soft tinted clay. The hollows thus formed are filled with a semi-fluid clay of a rich or deep color poured into them and over the whole surface of the tile. In 24 hours this has becorne hard enough to admit of the surplus clay being removed, which is done by placing the tile, still in the box, upon a horizontal wheel, and as it revolves applying a knife or scraper entirely across, so as to rest upon the edges of the box. The surface is thus cut down so as to expose the pattern and the ground. The defects are removed with a knife, and the edges after being square are rounded off with sand paper. The tiles are kept for a week in a warm room called the greenhouse, and the drying is completed in another called the hothouse. They are then baked like other articles of pottery, except that double the ordinary time is given to the process, and the oven is left six days to cool before the tiles are taken out. They contract in baking from one eighth to one sixteenth of their dimensions.
The process is supposed to be nearly the same as that employed in the middle ages in France and England in making pavements for churches, and also for the beautiful pottery called Henry II.'s ware, peculiar to France in the 16th century. - The French apply the term encaustic to preparations of wax used for covering furniture and floors, which are then polished by friction.