Glazed ceramic tiles are made by applying a ceramic glaze to the surface of a clay tile and then vitrifying the glaze by subjecting the tile to temperatures of between 600 and 1300 degrees Celsius. The surface of the glazed ceramic tile is therefore close in chemical nature to a pigmented glass, and is subsequently resistant to chemicals and is nonporous in nature. Glazed ceramic tiles may be high gloss or matt, and may have a uniform surface or a profiled surface. Sealing of glazed ceramic tiles is not recommended. The sealing of the grout between the glazed ceramic tiles is however recommended to resist staining and allow for easier cleaning.
Vitrified, Full-bodied and Split Tile are all terms used to describe the type of tile used mainly for industrial or heavy-duty applications where the whole body of the tile has been heated to such a high temperature and held at high temperature for so long that the entire tile becomes almost vitrified and extremely hard. These tiles are sometimes made by the "split-tile" method, where the clay is extruded into shape in a double form, and then, after firing, split by means of a cutter. This is why the term “Split Tile” is often used to describe vitrified tiles, although this method of manufacture is sometimes also used to make low-fired clay tiles. Punched clay tiles can be made by the same method. Although extremely hard and dense these tiles do require sealing to prevent staining from mineral oils, fats and organic matter. Sealing also reduces water staining in these tiles. Repellents or impregnators are best used for these types of tiles.
Porcelain tiles are vitrified or full-bodied and are generally available in natural form or polished. Polished porcelain is produced by means of artificially diamond polishing the fine clay to a mirror like finish. Porcelain tiles have very low porosity or absorption rates (usually less than 0.03 percent by weight), but due to their crystalline structure have a peculiar surface porosity which makes them sometimes difficult to clean. Certain polished porcelain has a tendency to stain. Porcelain tiles come in a wide variety of colours , blends and surface textures. Porcelain tiles are used as wall and floor tiles, and as wall cladding in certain environments.
