Porcelain tile is a type of dense, durable ceramic tile that does not easily absorb water or other liquids. Both tiles are manufactured similarly using baked clays, so it is primarily the strength and density the tiles that separates the two. Ceramic tiles are generally more absorbent and delicate, so they work better in indoor places that are not likely to get damaged, such as kitchen backsplashes. Porcelain tiles are much less absorbent than ceramic tiles, and so they are suitable for outdoor use and high traffic areas. Porcelain tiles tend to be more expensive than ceramic tiles but are more useful in a wider variety of applications.
edit Clays Used in Ceramic vs Porcelain Tiles
Ceramic tiles are made with red, brown, or white clay, while porcelain tiles are almost exclusively made with refined and purified white clay. The clays used in porcelain tend to have fewer impurities than clays used in ceramic tiles and have more kaolin and feldspar. This ultimately results in a denser and more durable tile.
Ceramic and porcelain tiles can be any color and even made to look like other materials, such as wood or natural stone. However, the design on a porcelain tile is more likely to withstand damage, as porcelain tile design goes throughout the entire tile. Designs on ceramic tiles are merely "printed" on top and then covered with a glass-based glaze. This means that a chip on a ceramic tile is much more noticeable than a chip on a porcelain tile.
Ceramic tiles are appropriate for areas that will not be subjected to heavy use or harsh conditions. Art mosaics, walls, kitchen backsplashes, and countertops that will only be lightly used or have glass overlays are all areas that can use ceramic tiles. Ceramic tiles should almost always stay indoors, as typical weather conditions — hot, cold, or rain — can cause ceramic tiles to become weak and crack. Like granite, ceramic is porous, meaning ceramic tiles may absorb liquid spills that could cause staining.
Because porcelain tiles are much more durable and stain resistant, they can be used inside or outside for walls or countertops and even in high traffic areas as flooring. However, not all porcelain tiles are the same, meaning it is important to purchase the right kind of porcelain tiles. For example, only some porcelain tiles are that are manufactured for outdoor use.
While porcelain tiles have long been a more stain resistant alternative to porous surfaces, they are not as durable or as stain resistant as some modern surfaces, such as quartz and Corian. However, they are more affordable and can even be made to look like natural stone.
Porcelain tiles are much more durable than ceramic tiles. In particular, they are less likely to absorb water than ceramic tiles are. This makes porcelain tiles more immune to rain, ice, or liquids which might cause stains or other damage.
All ceramic tiles are subjected to a water absorption test during their manufacturing process. Baked tiles are weighed before they are placed in water for up to 24 hours and then are weighed again after they are removed from water. Those tiles which weigh less than 0.5% more after being submerged are considered dense enough to be classified as porcelain. Tiles that weigh 0.5% more or greater — i.e., those tiles that absorbed more water — are considered ceramic.
edit Porcelain Enamel Institute (PEI) Ratings
Ceramic and porcelain tiles are often given class ratings from the Porcelain Enamel Institute. There are six class ratings (0 to 5), altogether, which indicate how hard and impervious a tile is. A PEI Class 0 rating suggests a tile is delicate and not suitable for any foot traffic, while a Class 5 rating indicates a tile is very durable and suitable for high foot traffic in commercial areas or perhaps even outdoor use.
Most ceramic tiles receive a PEI class rating of 0 to 3, while most porcelain tiles receive a class rating of 4 or 5.
edit Porcelain Tile Certification
Marketing terms can sometimes make it difficult to know whether a tile is ceramic or porcelain. This is highly problematic considering ceramic and porcelain tiles often have very different applications. The best way for homeowners to ensure they are purchasing porcelain tiles is to look for tile that has been certified by the Porcelain Tile Certification Agency (PTCA). The PTCA maintains a list of certified porcelain tile sellers on its website.
While neither ceramic nor porcelain tiles are very expensive compared to other countertop or flooring materials, porcelain tiles are more expensive than ceramic tiles. Prices for both also vary according to tile density (i.e., according to PEI ratings).
Both ceramic and porcelain tiles can be very delicate to handle during installation. Ceramic is not very thick, meaning it can be easy to cut in a DIY project, but may also easily (and noticeably) chip. Porcelain tile, meanwhile, is so hard that it may be brittle and prone to cracking when handled with unskilled hands. Once installed, both tiles should function relatively well if the right class of tile has been used in the right place. Installation of either tile, however, will almost certainly require a professional.