Porcelain Outdoor Tile began only in the 1300s, when the Chinese introduced finely ground sand into white clay, known as kaolin, and fired the composition at temperatures that greatly exceeded that of ceramic kiln firing. Because of the intensity of heat during firing and the quality of its composition, Retro Porcelain Outdoor Tile is denser than ceramic, less porous and doesn’t absorb moisture or stains as easily as ceramic.