ENCAUSTIC TILES, ornamental tiles made of earthenware, and now extensively used for paving churches, halls, conservatories, etc. Strictly speaking, the name applies only to tiles with a pattern produced by layers of different-colored clays; but we may also include those made of a single color where two or more kinds go to form a pattern. Of course a mosaic can thus be formed with tiles of various forms as well as colors. . Tiles of one color are made of dried slip—that is, the powder of carefully mixed and prepared clay. These "dry tiles" are made by placing the colored clay powder in strong steel molds, and subjecting it to a pressure of several hundred tons, by means of a plunger fitting accurately into the mold. A depth of 3 in. of powder is compressed into a tile of 1 in. in thickness. It is then removed, heated iu a hot chamber, fired, and glazed if required.
The figured tiles are made in a different manner. The clay is worked in a moist state, but very stiff, first into square blocks. These are cut into square slices or slabs by pass ing a wire through them; upon this is put a facing of fine clay of the color of the ground of the pattern—another layer, of a different quality of clay, is sometimes added to the bottom, to prevent warping. It is then placed in a mold, with a plaster-of-Paris slab forming the top, on the under surface of which is the pattern in relief. This slab is pressed down, and thus forms a deep impression of the pattern which is to be produced in another color. The clay of the requisite color to form the pattern is now poured, in
a semi-fluid state, into this depression, and allowed to flow over the whole face of the tile; then it is set aside until dry enough to have its surface scraped and smoothed on a whirling table. means uiertluous c1< is removed, and the pattern is _ • ,•.k. •%I.1 brought out clear and well-defined, the two colors of clay forming one smooth flat sur face. The tile is then dried and fired.
By Malkin's patent process, inlaid as well as plain tiles are now wholly made of dried slip. The pattern is produced by the use of brass plates one eighth of an inch thick, a separate one being used for each color. Thus, if it consist of an ornament in red and white on a blue ground, one plate is perforated so as to enable the red portion of the clay powder to be filled in, another is cut for the white portion, and a third for the blue ground. When all are filled up, the tile is pressed in a screw-press and fired.
Tiles of this kind were used for paving churches in England and on the continent from the 12th to the 15th c., after which they fell into disuse. The modern manufacture is therefore nothing more than a revival, with some improvements, of an ancient art.