Ceramic tile. Now there's a term for you. When hearing or reading it, most people think of the highly glazed "bathroom" tiles of years gone by or of decorative tiles which are used to dress up otherwise plain tile installations. After all, aren't there many different kinds of clay tiles? Aren't ceramic tiles just a small part of the field?

Actually, no. The term "ceramic tile" covers almost every clay product produced and used within the tile industry. In addition to four-and-a-quarter-inch bathroom tiles and colorful "decos," there are "monocottura" or single-fired floor tiles, 1-inch and 2-inch "mosaic" tiles mounted on sheets, double-, triple-, and even quadruple-fired tiles decorated in dozens of different ways, and large format porcelain tiles which are used on floors and walls. It is this last category of tiles that we will concern ourselves with here. There is a great deal of confusion concerning the status of porcelain tiles, most of it generated within the tile industry itself.

Sales of floor tiles in the U.S. and Canada have doubled in slightly over a decade, and the popularity of tiled floors continues to increase at a dramatic rate. The rise in tile sales can be attributed to two factors primarily: a determined and well-thought-out effort developed and sustained by marketing and sales forces within the industry; and by constant and significant improvements achieved by tile manufacturers over the past couple of decades. In slightly over twenty years we've come from fairly soft "knob-back" floor tiles made from terracotta-like clays to extremely dense dust pressed porcelains that are all but indestructible. Walk into any tile salesroom today, and you will find mostly porcelain tiles displayed.

Ask a tile sales person whether porcelain tiles are stronger and more durable than ceramic tiles and in most cases the answer will be yes. But although porcelain tiles are indeed strong and durable, that answer is essentially incorrect. As I stated above, porcelain tiles ARE ceramic tiles. Porcelain is simply a type of ceramic clay. Porcelain tiles are those which have the lowest absorption rates of all the ceramic tiles available. To be classed as "porcelain," a tile cannot absorb more than .5 percent of it's total mass in water. Many porcelain tiles absorb less than that -- down to as little as .1 percent. In the industry, these tiles are called "impervious."

There is no confusion on this matter among installers. We call ourselves ceramic tile setters, not porcelain tile setters. It's just that as it turns out, most of the floor tiles we install nowadays are made from porcelain.

But the misinformation continues. The Porcelain Enamel Institute rates glazed floor tiles as to their resistance to abrasion. Glazed tiles are those to which a decorative layer has been applied over the clay body of the tile. Glazes are rated 1 through 5 with 5 being the highest or most durable grade. Many, if not most, porcelain tiles are not glazed, yet ask your tile sales person about the PEI rating of the porcelain tile you are examining in the showroom. It's very likely you'll hear something like, "Oh, this is a grade 5 porcelain tile. You could lay this baby in a car factory."

I certainly don't aim to demean tile sales people. We need them and love them. Without them we'd be out of work. I do wish they'd get themselves a little better informed, though, so they can better inform the buying public about the virtues of ALL ceramic tiles.

John P. Bridge is the author of three books on tile setting: Ceramic Tile Setting, McGraw-Hill, 1992; Tile Your World, Mistflower Press, 2003; The Kerdi Shower Book (eBook), Mistflower Press, 2005. Bridge also operates the John Bridge Ceramic Tile Forums on the Internet. http://www.johnbridge.com/vbulletin/index.php

A veteran of 33 years in the tile business, John is a residential tile contractor in Houston, Texas, where he resides with his wife Patti.