Porcelain vs. ceramic tile: Is this a war between two vastly different types of materials or simply a war of words? The terms porcelain and ceramic are often used interchangeably as if they were the same thing. Tile shop salespeople often claim a world of difference between the two in order to justify porcelain's cachet and its higher prices.
As it turns out, ceramic and porcelain are composed differently and do behave accordingly upon installation, but with only slight differences. The chief difference is that porcelain tile is more impervious than ceramic tile and is thus subject to greater water infiltration.
According to the industry group that decides whether a tile is porcelain or ceramic, everything boils down to that one issue: meeting a set of water absorption criteria. Another standards group, this one independent of the tile industry, even pushes the definition further by stating that porcelain is dense, impervious, fine-grained, and smooth, in addition to the same water absorption criteria.
Porcelain and Ceramic: Both From the Family of Ceramic
Porcelain and ceramic tile are both are part of the larger category of tiles that can generally be called ceramic. For modern tile specifications, it is more a case of reverse-naming, whereby manufacturers take tiles that have certain qualities and then assign the ceramic or porcelain titles to them.
Add a healthy dose of marketing and branding, as the tile industry is prone to touting porcelain's storied history. The word porcelain's Italian etymology is porcellana, or cowrie shell. Fine porcelain-ware is white, translucent, strong, and it has a fine, dense body. Marketing materials often mention how fine china, which can be both rare and very expensive, is made of porcelain.
But little of that applies to the porcelain tile of today. This is a different ball game, a game of branding and certifying, and has few connections with fine china. Certification is more than just protecting manufacturers' interests and limiting liability. It is a shortcut that consumers can use to quickly identify which types of tiles they are getting. And certainly, porcelain tile and ceramic tile can be considered close cousins when discussing other, wildly different types of tile such as quarry tile, glass tile, or natural stone.
Porcelain Has a Low Water Absorption Rate
Porcelain tile has a water absorption rate of 0.5 percent or lower as defined by American Society for Testing and Materials (ASTM) section C373. First, fired tile is weighed. Then it is boiled for five hours and let to sit in water for 24 hours. Next, 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.
Porcelain tile is often extruded; has fewer impurities than ceramic; is often rectified; and often contains more kaolin than ceramic. It is formed of quartz, clay, and feldspar that is fired at temperatures ranging from 1,200 to 1,400 degrees C.
But since that also defines many ceramics, again the difference is that porcelain has that 0.5 percent or less water absorption rate.
Porcelain Is Certified as Porcelain by Industry Groups
For years, tile manufacturers and tile distributors did not see eye to eye on the issue of how to define porcelain vs. ceramic tile. By 2008, the debate had reached such a fevered pitch that the manufacturers, represented by the Tile Council of North America (TCNA), and the distributors, represented by the Ceramic Tile Distributors Association (CTDA), formed a third-party organization to settle the differences and come up with a standard definition for porcelain tile. They called this new group the Porcelain Tile Certification Agency (PTCA).
According to the PTCA, it is not simply enough for a tile to be "impervious" (a favorite tile term, meaning that it is good against water). The tile has to meet those ASTM C373 standards of water absorption by sending in five tile samples for testing, paying a fee, submitting a participation agreement, and renewing certification every three years. After certification, a company may use the PTCA Certification Mark branding. At last count, 28 North American tile companies had received certification as producing authentic porcelain tile.
How Do You Know That Porcelain Tile Is Really Porcelain Tile?
The PTCA's fight did not end with the establishment of water absorption criteria. Today, about 70 percent of the tile purchased in North America is imported. The PTCA indicates that much of the imported tile that is prominently labeled as being "porcelain" is actually not porcelain.
In one independent blind test conducted by the TCNA, 1,466 tiles were tested for the water absorption criteria that would qualify those tiles for porcelain status. The conclusion was startling. Close to 23 percent (336 total) of the tiles tested that were labeled as "porcelain" were actually falsely labeled. In other words, they absorbed water over that 0.5 percent benchmark. In some cases, the so-called porcelain tile had an alarming 3 percent absorption rate.
This is an on-going fight for the PTCA, especially since more and more tiles are being imported. As a self-policing, self-funded organization, the PTCA lacks the resources to test every single tile that crosses the international border for water absorption criteria.
One way to determine if a porcelain tile is truly porcelain is to check the box for the PTCA Certification Mark. Currently, this is the distinctive green and gray logo that reads "Certified Porcelain Tile 0.5% water absorption," with a diamond-shaped tile forming the "O" of "porcelain."
However, the PTCA mark is subject to change. Plus, dishonest tile companies may fraudulently mislabel their boxes. That being the case, the only way to know for certain if that tile is truly porcelain is to check it against the PTCA's on-going database of tile makers and their series of porcelain tiles.
Broader ANSI Definition of Porcelain vs. Ceramic
The PTCA's sole interest is in assuring that tiles that are labeled as porcelain meet or exceed water absorption rate standards. But it can also be helpful to look at standards defined by American National Standards Institute (ANSI) A137.1, which says in part that porcelain tile can be defined as tile that is produced with a "dust-pressed method of a composition resulting in a tile that is dense, impervious, fine-grained, and smooth with a sharply formed face." It is important to note that ANSI A137.1 also references those important ASTM C373 standards of water absorption rates.
Where to Use Ceramic or Porcelain Tile
While it depends on who you ask, laying porcelain or ceramic tile outside is typically not recommended. Tile industry representatives may rightly claim that porcelain tile is fine for exterior use. Others may rightly claim that other paving or flooring materials such as quarry tile, concrete, or natural stone such as slate or marble work better outdoors than ceramic or porcelain tile.
What is most agreed upon, though, is that ceramic tile should not be installed outdoors. Ceramic tile is not durable enough for exterior use because it absorbs too much water. If you live in areas which freeze, your tile would likely crack within the first few freeze-thaw cycles.
Within the category of exterior porcelain, it can be helpful to consult Porcelain Enamel Institute (PEI) ratings, too. PEI ratings for porcelain tile tend to be around PEI 5 (heavy residential and commercial traffic). PEI ratings for ceramic tile can range anywhere from PEI 0 (no foot traffic) up to PEI 5, but with most ratings in the lower end of the scale.
Porcelain Tile Density and Long-Term Durability
Porcelain clays are denser and thus less porous than ceramic clays. This makes porcelain tile harder and more impervious to moisture than ceramic tile.
Not only is porcelain tile more dense than ceramic tile, but due to its through-body composition, it is considered more durable and better suited for heavy usage than ceramic tile. Chip the ceramic tile and you find a different color underneath the top glaze. Chip the porcelain and the color keeps on going, all the way through. As a result, the chip is nearly invisible.
While both porcelain and ceramic are fired at high temperatures, porcelain is fired at even higher temperatures and for a longer time than ceramic. Also, porcelain has a higher feldspar content, which makes it more durable.
Ease of Cutting
Tile density has a good side and a bad side. While ceramic tile is less dense than porcelain tile, it is also a far easier material for do-it-yourselfer homeowners to cut manually, by wet tile saw, or with a snap tile cutter. Porcelain tile is more brittle and may require the experienced hand of an experienced tile-setter to cut properly.
Price Differences of Porcelain vs. Ceramic
With all other factors equal, ceramic tile is cheaper than porcelain tile. Ceramic tile tends to run about 60 to 70 percent of the cost of porcelain tile. Both ceramic and porcelain tiles in the top 15 percent of their price ranges tend to be close in terms of price. But going below that top 15 percent, prices dramatically diverge between porcelain and ceramic tile.
Unless there is some anomaly in pricing, ceramic tile will nearly always be cheaper than porcelain tile. Porcelain is more expensive to manufacture than ceramic tile, resulting in higher retail prices.