Porcelain tile has a water absorption rate of 0.5 percent or lower as defined by the American Society for Testing and Materials (ASTM) section C373.2 To test this, the fired tile is first weighed, then it is boiled for five hours and left to sit in water for 24 hours. Then it is weighed again. If the tile weighs less than half of one-percent more as a result of water-absorbing into its surface, it is considered porcelain.
To achieve this density, a special kaolin clay mixture is used, which is finer and purer than most ceramic clay. It usually contains notable levels of quartz and feldspar mixed in. Porcelain tiles are fired at temperatures ranging from 2,200 to 2,500 degrees Fahrenheit. To the consumer, it generally suffices to say that porcelain is a dense, fine-grained, smooth tile that is more impervious to water than ordinary ceramic tile.
Porcelain tile virtually always receives a surface glazing treatment—a coating of liquified glass material—while some forms of ceramic tile are left unglazed. As a rule porcelain tile is more impervious than ceramic tile and is thus subject to less water infiltration.
One recent innovation with porcelain tile is the ability to manufacture them to resemble different materials. While ceramic tile generally has solid color and pattern, porcelain tiles are available that are remarkably good at mimicking natural stone such as marble or even wood grains. This makes porcelain tile an excellent choice where you want the look of wood without wood’s susceptibility to water damage.
Porcelain tile has the edge when it comes to appearance, for the simple reason that it is available in more colors, patterns, and surface finishes, including tiles that resemble wood grains and natural stone.
Porcelain has slightly better water resistance, making it possible to use it in outdoor locations in regions with mild climates. Ceramic tile is generally not recommended for outdoor locations in any environment.
Porcelain tile is very easy to clean up by damp-mopping with a mild water-soap solution. The cementitious grout filling the joints between tiles needs to be periodically sealed to guard against stains and mildew.
Porcelain clays are denser and thus less porous than ceramic clays. This makes porcelain tile harder and more impervious to moisture than ceramic tile. Due to its through-body composition, it is considered more durable and better suited for heavy usage than ceramic tile. Chip a porcelain tile, and the color continues all the way through; as a result, the damage is nearly invisible. Porcelain is an easy material to maintain, requiring only period sealing of the grout lines.
As a harder material that has solid color throughout, porcelain tiles are stronger and more durable, and chips are less likely to be visible.
Porcelain tile is more brittle and may require the experienced hand of an experienced tile-setter to cut properly. A wet tile saw is the recommended tool for cutting porcelain, while an inexpensive snap cutter generally works fine with ceramic tile.
Porcelain is more expensive to manufacture than ceramic tile, resulting in higher retail prices. Porcelain tiles begin at about $3 per square foot, running to $35 per square foot.