Ceramic tile can best be characterized as either porcelain or non-porcelain. Traditional ceramic tile is non-porcelain and is made from white, red, and/or brown clay and other minerals. Porcelain ceramic tile is made from clay and minerals as well, but it also contains 50% of a white dust or sand called feldspar. Feldspar is a type of crystal found in rock that acts as a "flux" during the kiln-drying process, melting into a glass-like material and bonding all of the molded ingredients together. Minor modifications to the ingredients of ceramic tile or the kiln-drying process (i.e., to the temperature and type of kiln) create enormous variety in the appearance and characteristics of manufactured ceramic tile flooring products.
Porcelain and non-porcelain ceramic tile can be either unglazed or glazed. Glazed tile has a matte, semi-gloss, or high-gloss finish applied to the surface during the manufacturing process. In the past, glazed tile was kiln-fired twice, once to harden the tile mold and a second time to harden the glaze. Today, in addition to double-fired ceramic tiles, an automated single-fired manufacturing process called Monocuttura hardens a glazed mold in one step. Glazed tiles have increased stain resistance, scratch resistance, and traction, as well as decreased water absorption, in comparison to an un-glazed tile.
Non-porcelain, ceramic tile is among the most economical types of tile flooring. Porcelain ceramic flooring is more expensive than non-porcelain and can be harder to work with. However, it offers greater durability, natural stain resistance, minimal water absorption, and through-bodied color. Many types of tile are manufactured in a similar fashion to ceramic tile, but they are less common. These include brick, cement, glass, encaustic, saltillo, and terra cotta tile. The varying materials and manufacturing processes create distinctive product characteristics.