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Understanding Materials: Ceramic Tile

Ceramic products are varied and depending on their manufacturing processes, they exhibit their own special qualities and properties. The hardness of the ceramic material is directly attributed to its manufacturing process, and generally references the Mohs Scale to categorize its hardness.

The Manufacturing Process

Ceramic tile production begins with the excavation of clays to be used in the manufacturing process. Depending on the type of tile being produced, any number of two to six different types and colors of clay may be necessary to blend together in a mixture.

The selected bulk clays are mixed with water and this mixture is pumped into large, rotating cylindrical mills, where extreme grinding action pulverizes the clay into uniform and homogeneous particles. This substrate is called “body-slip,” and has the consistency of a milk shake.

Next, moisture from the body-slip is evaporated by a spray dryer burner, creating fine particles of uniformly sized dry clay called “powder.” The powder is then fed into molds within a hydraulic press, where it is molded under pressure (approximately 4,000 PSI) to form “green ware” (what the tile is called prior to being fired). The green ware is dried again to further reduce the moisture content, and then travels down “glaze lines” where various types of glazes are applied to the surface.

The glazed green ware travels through a kiln and undergoes a 45-50 minute firing where temperatures can reach 2300°F causing the glaze to fuse to the body. The tile that emerges from this process is very hard, durable and impact resistant.

Hardness of Ceramic Tiles