Porcelain vs. Ceramic Tile, Part 2
How to Choose Ceramic Tile

Your understanding of rest of this article will be greatly improved if you first read Part 1.
Back to Part 1: Porcelain vs. Ceramic Tile: What is the Difference

We suggest that you ignore the term por­ce­lain when shopping for fired clay tiles. It tells you nothing useful about the tile. As we explained in Part 1 of this article, the term por­ce­lain is used in so many ways to mean so many things that it has lost all usefulness and merely causes a great deal of confusion.

You can't tell the color the body of the tile because all of the exposed surfaces are glazed. Special glazed tiles called bullnose tiles are used to go around corners. But, even if these special tiles are not available your tile setter has a few tricks to disguise the unglazed edge of the tile.
The tile is terra-cotta, by the way — not that it matters.

This is not new. The English ceramicist, Wm. Burton, writing in 1906, noted that the term had already been applied to such diverse materials that it had "lost all meaning"1.

To avoid becoming a victim of the confusion and misinformation surrounding por­ce­lain, and possibly ending up with overpriced tile you don't need, disregard the dubious distinction between por­ce­lain and other ceramic tile. It actually makes choosing the right tile much, much easier.

There are only two things you actually need to know about any fired clay tile.

First, do you like it? Does the size, pattern, price and color all work for you?
Second, what are its ratings. Has the tile been tested and rated for the use you intend for it?

The ratings tell the tile's whole story including where and how it may be used and if it is suitable for the application you have in mind. If a tile is rated for the application you intend, it will work irrespective of whether its manufacturer choses to call it por­ce­lain.

If you can answer yes to both questions, great! You've knocked it out of the ballpark.

The Tile Glaze

Some fired clay tiles — quarry and saltillo tiles, for example — are not glazed. The color of the tile body is the color you see, so it makes a difference what clay was used to make the tile.

But, most ceramic tiles have a coat of opaque, glassy material on the face of the tile that we call the glaze.

There are emerging one-step (or "monocottura") processes in which the tile and glaze are fired at the same time. But, traditionally, glaze is applied after the biscuit is fired, then the tile is fired again to set the glaze. This is called a "bicottura" or double firing method. It's this glaze that gives the tile its color and texture, not the composition of the tile body. The glaze is the tile's paint.

Glaze vs. Enamel

In the tile world, the glass finish applied to ceramic tile is called the "glaze". In the bathroom fixture industry, the glass finish is called "enamel" — hence the term "enamelware". The two terms mean exactly the same thing, but there is an historical basis for the different names.

The traditional term, going back to the 15th century in the jewelry-making trades, for glass applied to metal was "enamel". The process involves grinding glass into a powder (called "frit") which is applied to metal that has been fired hot enough to melt the frit. It is not only beautiful, but is the ideal material for protecting metals from damage by water.

With something small like a broach or finger ring, enameling metal is fairly simple, but what about something the size of a bathtub? Industrial scale enameling was not possible until 1880s when American Standard and Kohler Co. separately developed processes for coating large iron objects — giving birth to the modern bathroom fixture industry.

Following the old tradition, the glass coating was called enamel. When sanitaryware manufacturers began applying over-glaze to ceramic bath fixtures like toilets and sinks, rather than iron fixtures, like tubs, they kept the term "enamel" instead of adopting the pottery term, glaze.

Enamelware was durable, very sanitary, and easy to maintain; and became an instant hit with American homeowners of the late 19th century who were avid for anything hygienic and sanitary. (See Arts & Crafts Styles: Craftsman, Prairie and Four-Square Architecture for more information). They were so superior to the earlier wood and metal products, that the old products were literally driven from the market within a decade.

Paint manufacturers soon took note of the reputation of sanitary enamelware in the public mind, and seeking to capitalize on the name, started calling some varieties of their more durable paints "enamel".

Fixture manufacturers were a little miffed when the paint guys tried to steal their glory, and fought if for years. They lost. Paint companies can call their paint "enamel". Today, sanitary fixture manufacturers refer to their glazing as "por­ce­lain enamel" or "vitreous enamel" to distinguish it from that other stuff the paint companies sell.

Think of wood siding. You don't see the wood in your siding. What you see is the coating on the wood — the paint. Most likely you don't even know what kind of wood was used for your siding, or if it was wood at all. It may be Masonite® or one of the more contemporary products, fiber cement siding, for example, which is a wood fiber and portland cement composite.

The same is true of glazed tile. Once tile is installed you can't see the tile body, you see only the glaze. So what difference does it make if the tile body is white, sand, terra-cotta or puce? If you need to go around a corner where the edge of the tile will be exposed, there are special edge tiles made just for that purpose. And, if you can't find a matching edge tile, your tile setter has a few tricks to disguise the edge.

With unglazed tile like quarry and saltillo tile the color of the tile body is exposed, so body color makes a difference to the finished look. In glazed tile, on the other hand, the body is entirely concealed by the decorative glaze, so the tile's body color is irrelevant.

Glazing was, until just a few de­cades ago, more art than science. It took many years of study under a master glazer to learn the combinations of minerals and additives, the heat variations and the amount of time in the kiln that would produce the many colors, lusters and textures on tile and pottery. Now it is mostly science. Consistent glazing compounds and standardized processes make is easier to reproduce the same finish over and over with great accuracy. So, while it is still desirable to get all of the tile you may need from the same firing, it is not nearly as important as it once was. Glazers can match most basic glazes from batch to batch so that any differences are almost invisible.

By the way, we have heard mentioned from time to time that the glaze on good por­ce­lain tiles has more "depth" than that on ceramic tiles, but that's just another nonsense myth. Glaze is "deep" if the glazer applies a thick coat of glaze, it makes no difference what kind of backing material the glaze is applied to. Even concrete blocks can have a "deep" glaze. This is yet another of those fables surrounding por­ce­lain tile that just won't go away.

How to Read a Tile Label

Once you have found the size, color and pattern of a tile that you like, then all the other information you need to assess the usefulness of the tile is printed somewhere on the box, often in the form of icons. These icons tell us all about the tile. And, since their use is regulated, the information in the icons is probably not going to be just marketing hype.

Let's see just what these icons can tell us.


Tile Grade

Grade Icon
Tile grade is the result of a visual inspection. The range is 1 to 3, the lower the number the better the tile.

Grade 1 or Standard Grade tile exhibits no obvious imperfections when visually inspected at a distance of 3 feet.

Grade 2 (Secondary Grade) tile shows no visible imperfections at a distance of 10 feet.

Almost all tile in a tile store will be grade 1. Sometimes you will find grade 2 tile on a "special purchase" sale — often at quite the discount. Grade 2 is just fine for many applications. The durability of a grade 2 tile is usually not suspect, it merely has visible imperfections. We sometimes use it in historical renovations to simulate 19th century tile that often had many visible flaws.

Grade 3 (Cull Grade) tile is rarely seen in retail stores. It usually has major aesthetic problems including wide variations in tone and sizing. Let the tile professionals buy this tile. They know where and how to use it.

Wear Resistance

Wear Rating
This is the result of the PEI wear test that we introduced in Part 1. Many manufacturers use this test only on floor tiles. The higher the rating, the more wear-resistant the tile. A tile used as flooring or on a countertop should be rated at least in Group II (light traffic floors). A higher rating is even better for floors with medium or heavy traffic.

Floor tile should also be at least 1/4" thick. Thicker is generally better. If the tile is glazed, then it is the glaze coating that is tested. If the tile is un-glazed, such as in quarry tile, the tile body itself is tested. The tests are slightly different. If this rating is missing, the tile is probably not intended for floors — and will usually say so right on the box.

Water Absorption

Grade Icon
This is the score the tile received on the ANSI test for resistance to water penetration (See Part 1 for more information.). A tile that is installed outdoors where there is a real Winter should not absorb water. Otherwise, water trapped within the tile may freeze, fracturing and cracking the tile. Almost all tiles rated impervious will work outdoors, but so will some vitreous tiles. Look for the frost rating (see below). For indoor applications, semi-vitreous and vitreous are strong enough for floors, and non-vitreous for walls.

All tiles called "por­ce­lain" do not necessarily rate "impervious". Don't rely on the word "por­ce­lain" on the box, look specifically for a frost rating or a W.A. score of "impervious". Some hardy tiles intended for use outdoors will have both. If there is a PCTA certification of "por­ce­lain", then the tile has been tested for water absorption and found to be impervious, and this certification is a substitute for a W.A. rating of "impervious".

Slip Resistance

For floor tile, this Coefficient of Friction (COF) ranking is important. The test establishes how much force is required to move an object across the face of the tile, dry or wet. It tells you how resistant a tile is to slipping. The higher the score, the more slip-resistant the tile.

Tile COF can be rated "wet" or "dry". For a general floor, both require a dry rating of 0.6 and above for a dry floor to be considered "safe". For a bath or kitchen, where the floor is likely to get wet, a wet rating of 0.6 or greater is required and 0.7 or higher is better. Some tiles specifically designed for wet floors are rated above 0.85 wet — a floor you could not slip on even with great effort.

COF is an important consideration, especially in wet areas. One of my neighbors ignored COF when selecting impervious tile for his front stoop, and now, on wet days, you have to tip-toe over the tile with a death-grip on the handrail to avoid great bodily harm.

There are some problems with this test, however. The approved testing process (ASTM C1028-07), involves pulling a weighted board with a Neolite® (rubber) sole (used to simulate the bottom of a shoe) along the surface of a test tile. This is called a static slip test. However, the way we walk involves more than just slip-sliding along. There is both downward and outward force applied with each step we take. The static slip test tells us nothing about the effects of these forces.

To test downward and outward force, what's needed is a kinetic or "dynamic" test. There are a number of dynamic resistance tests. The most widely accepted test in Europe is the ramp test (DIN 51130) developed in Germany. The test involves a person walking along a ramp of tiles that are being tested. The ramp's incline is increased to a point where the person slips

Obviously, since people react differently when anticipating a slip — including changing their stride and walking more carefully — and some acrobatic individuals can airily skip down slippery slopes that would kill us clutzier types, this test has some basic reliability problems. It has not been widely adopted outside of the European Community.

The static slip test has its own reliability problems. It often misreads the slipperiness of wet surfaces, showing them safe when in fact they are not. Both the Ceramic Tile Institute of America, and Tile Council of North America have acknowledged that the test is inadequate for assessing the slip safety of ceramic tiles.

The most promising replacement is the Dynamic Coefficient of Friction test (DCOF/ACU). The testing protocol requires a BOT-2000 drag-sled meter that crawls along the tile under its own power at a constant speed measuring the resistance to slip of a standardized piece of rubber loaded into the bottom of the machine. The minimum acceptable DCOF test value for floor tile using this test is 0.42 wet or dry. Below .30 is considered unacceptable for floor tile.

At the moment many tile companies are using and reporting both the static slip test and the BOT-2000 test, but the expectation is that eventually the static test will be discontinued altogether.

Breaking Strength

Grade Icon
Breaking strength is important for floor tiles. When you step on a tile, you don't want it to snap. The tile industry uses ASTM C648-04 to determine the strength of the tile. A force is applied to an unsupported portion of the tile specimen until it breaks. The tile's breaking strength is stated in pounds of force applied.

A tile for use on floors must have a breaking strength of at least 250 lbs. Higher is better. And, if Uncle George, even after his last diet, still weighs in at a crushing 380 lbs. or so, higher is definitely required. This rating is typically not printed on the tile box or data sheet. It is simply assumed if the tile is intended for floors. You may have to telephone the tile company to get the actual rating.

Chemical Resistance

Grade Icon
Chemical resistance is measured using ASTM C650-04. A tile sample is placed in continuous contact with a variety of chemicals for 24 hours, rinsing the surface and then examining the surface for deterioration and visible color or texture variations. This is a pass/fail test. If there is any change in the tile, it fails and is usually not even put on the market or it is sold subject to limitations printed on the box or specifications sheet.

Stain Resistance

Grade Icon
Stain resistance of ceramic tile is tested using a process specified in ASTM C 1378. Various
Stain Grading Table
RatingStain completely removed with ...
5Hot water
4Weak cleaner
3Strong cleaner
2Solvent specific to the staining agent
1Stain not removed
staining agents are placed on a minimum of five sample tiles. Each staining agent must remain on the samples, for 24 hours. They are then removed. The tile is rated by the strength of the cleaner required to completely remove the stain.

Tile must test at class 3 or higher to pass — the stain must be completely removed with, at most, a strong cleaner. Typically the result is reported as merely pass/fail. Almost any glazed tile will easily pass this test. Of more concern are unglazed tiles such as quarry or saltillo tiles. When buying these tiles, you will want to know the tile's stain resistance class.

Freeze Resistance

Grade Icon
The "Frost" icon tells you that the tile is able to withstand repeated cycles of freezing and thawing. And, that's how its tested. It is put through multiple freeze/thaw cycles to see if it will show damage. The result is reported as pass/fail. If it cracks, it fails. The body of a tile rated "impervious" in the water absorption test will almost always withstand repeated freeze/thaw cycles, but this may not be true of the glaze. Some glaze will "craze", i.e. form small cracks. This frost test subjects the glaze as well as the body of the tile to freeze/thaw cycles to see if both parts of the tile can withstand the stresses of Winter.

If there is no frost icon, it means that the tile is not suitable for use outdoors in any place where it might freeze. Some tiles rated "vitreous" in the water absorption test will pass the frost test, and almost all "impervious" tiles will pass.

Tone & Shade Uniformity

Tone & Shade Table
V1 RatingV1 (Low) indicates low visible shade and texture variation within each carton.
V2 RatingV2 (Medium) indicates a medium shade and texture variation within each carton.
V3 RatingV3 High) tiles show distinguishable differences in texture and pattern within each color.
V4 RatingV4 (Random) file contains random variations of shade and texture within each carton.

Grade Icon
The tone and shade rating is an indication of how much variation there is in the color and shade of the tile. The range of ratings on this V-scale is V0 to V4. V0 (monochromatic) indicates no visible color or shade variation among the individual tiles.

Grades V3 and V4 need to be continually blended during installation to insure optimum appearance. This generally results in higher installation costs. Also, examine more than one tile, and more than one box of tiles to see if you like all the various tones. There may be considerable variation between cartons.

Some Informal Quality Tests

How did we tell good tile from not-so-good before there were these helpful package ratings? There are traditional tests that can be used to help judge the quality of a tile..

Here are some rule-of-thumb tests that have been around for many years.


The Weight Test

Hard fired tile is generally denser and therefore heavier than softer tile. You probably can't judge comparing single tiles, but heft the boxes. The heavier box is usually the harder tile.

The Ring Test

Hold a tile between your thumb and forefinger at one corner and let it dangle. Snap near the middle of the tile with your fingernail. A well-vitrified file with a high crystallization content will ring like a lead crystal glass. The sharper and higher the ring, the more vitrified the tile. If it goes "thunk", think of it as wall or backsplash tile.

The Color Test

Hard fired terra-cotta tile is generally browner. We don't know why. It may be the composition of the clay or the fact that high firing turns the clay browner. And, it's not always true. But, generally hard fired tile is browner.

The Completely Unofficial (and Entirely Unapproved) Ad Hoc Kinetic Slip & Fall Field Test

The COF rating indirectly tells you whether a tile is slippery, but it's not 100% reliable. The most accurate test is our Completely Unofficial (and Entirely Unapproved) Ad Hoc Kinetic Slip & Fall Field Test. It is a simple two part test.

1. Carefully place several tiles on a hard, level floor, well supported so they do not tilt or wobble.
2. Walk on the tile.

If you slip and fall, the tile fails the test. Don't buy it, and call your lawyer. If you need a wet kinetic slip test, toss some water on it first. The tile store clerk will probably go batty when you do this, but if you want to be completely satisfied that a tile is not slippery, do it anyway. We do.

The Informal Mohs Scratch Test

In 1882 mineralogist, Friedrich Mohs, developed a table of relative hardness of minerals which has since become well-known as the Mohs Scale. Each mineral was given a number, with talc, the softest mineral ranked as 1, and diamond, the hardest, ranked 10. The minerals are:

Mohs Table of Relative Hardness
RankMineralSubstitute
10Diamond
9Corundum
8Topaz
7QuartzCase hardened Steel File
6Orthoclase
5ApatiteWindow Glass
4FluoritePocket Knife Blade or Steel Screw
3CalciteCopper Penny
2GypsumFingernail
1Talc 

Each mineral in the table will scratch any mineral ranked lower in the table, but will not scratch any mineral ranked higher. Since most of these minerals are a little hard to come by in daily life — just what the devil is fluorite or orthoclase anyway? — substitutes are generally used for the informal Mohs scratch test. These are shown in the table.

The substitute will scratch any mineral lower than its place in the table, but will not scratch any material higher than its place in the table. So, a copper penny will scratch gypsum, but not fluorite, whatever that is.

Wall tile should be at least 4 on the Mohs Scale. You should not be able to scratch it with a copper penny. Floor tile should be at least 6 (7 is better in high traffic areas). You should not be able to scratch floor tile with a piece of ordinary window glass. If even a case-hardened steel file does not scratch the tile, it's some kind of alien super-tile, possibly escaped from a secret government lab in Area 51. Check for radiation!

Relative Hardness of Flooring Materials
RankMaterialTest With…
10  
9  
8
7Case-Hardened Steel File
6Ceramic Floor Tile
5Natural GraniteWindow Glass
4Ceramic Wall Tile, MarblePocket Knife Blade/Steel Screw
3Site-Finished Wood FlooringCopper Penny
2 Fingernail
1Vinyl Flooring

For comparison…

Vinyl floor tile and vinyl sheet flooring is Mohs 1-2. You can dent it with a copper penny and sometimes with a fingernail.

Site-finished wood flooring is Mohs 3-4 and can be scratched by a steel screw or pocket knife, but rarely with a copper penny.

Marble is also typically Mohs 3-4.

Natural granite tops out at Mohs 4-5. Some can be scratched with window glass, but not with a pocket knife.

Engineered quartz countertops are around Mohs 6 — tough stuff that can be scratched only with a case-hardened file.

Do not scratch a tile without the store clerk's permission. If the clerk does not give you permission, buy just that one tile, then see what will scratch it before committing to more.

You may not have to scratch it at all if the tile maker has conducted a formal Mohs test and printed a Mohs rating right on the box, and many tiles do. The rating is stated as a number from 1 (softest) to 10 (hardest). Values of 4 or more are suitable for walls and backsplashes, 5 to 7 for most floors. For very highly trafficked areas, or if hubby wears his golf shoes in the house, consider a Mohs value of 7. If the company claims a Mohs of 9 or 10, it's lying. No tile is this hard.

These rule-of-thumb tests should not be relied on by themselves. Read the ratings on the box. But, you can use these to impress the sales clerk with your deep and comprehensive knowledge of fired clay tiles. It also helps to throw around words like "monocottura" and "bisque" while you're at it, and refer frequently to ANSI A137.1 and wet and dry COF. You'll have the guy on the run after just a few minutes.

Choosing the Right Tile for Your Application

So, now you know a lot of rules and a few little tricks about ceramic tile, but you are probably asking yourself how you can apply the rules to make the best decision about buying tile for your bathroom, kitchen or sun room. Do you need PEI Group II or Group III, Vitreous or Semi-Vitreous? And, how about that Coefficient of Friction thingy?

Well, here's the table that shows how to put your new, in-depth tile knowledge to practical use in selecting the right tile for the particular use or application you have in mind. keep in mind that the table depicts the ideal tile for each application. Some of the combinations are probably not going to be found in the tile store. For example exterior walls call for a water absorption rating of "impervious", but a wear rating of just group I or II. Most likely you will have to move up to a Group III or IV because it is almost impossible to manufacture a tile that both impervious and soft. Chemically it cannot be done. So the lowest wear grade you are likely to find in an Impervious tile is probably Group III. More wear resistance than you need, but it's what's actually available.

Ceramic Tile Application Guide
(Minimum ratings for the application specified)
Wall Tile
ANSI Water AbsorptionPEI Wear ResistanceCOF
Dry Area
Non-vitreousGroup 1 or II1N/A
Tile wainscots, fireplace surrounds. Areas that rarely if ever get wet.
Wet Area
Semi-vitreousGroup 1 or II1N/A
Kitchen backsplashes. Areas that may get wet on occasion, but are unlikely to see constant or standing water.
Very Wet Area
vitreousGroup 1 or II1N/A
Shower walls. Areas that may get wet frequently and/or are likely to see constant or standing water. Exterior walls in areas that do not experience a hard freeze (and in areas that do experience a hard freeze if the tile is frost rated).
Exterior3
Vitreous (if frost rated) or Impervious2Group 1 or II1N/A
Exterior areas that experience a hard freeze in winter.
Floor Tile
ANSI Water AbsorptionPEI Wear ResistanceCOF
Dry Area
Light Traffic
Non-vitreousGroup II (Dry)
COF 0.60, DCOF 0.42
Bedrooms. Rooms where there is usually no through traffic.
Medium Traffic
Non-vitreousGroup III(Dry)
COF 0.60, DCOF 0.42
Family rooms. Areas of moderate through traffic or normal use.
Heavy Traffic
Semi-vitreousGroup IV(Dry)
COF 0.60, DCOF 0.42
Hallways. Areas of constant through traffic or heavy use.
Wet Area
Light Traffic
Semi-vitreousGroup II(Wet)
COF 0.60, DCOF 0.42
Laundry rooms. Areas where there is little traffic that get wet on occasion, but are unlikely to see constant or standing water.
Medium Traffic
Semi-vitreousGroup III(Wet)
COF 0.60, DCOF 0.42
Kitchens. Areas of some through traffic or moderate use that get wet on occasion, but are unlikely to see constant or standing water.
Heavy Traffic
Semi-vitreousGroup IV(Wet)
COF 0.60, DCOF 0.42
Kitchens with heavy through traffic. Areas of constant through traffic or heavy use that get wet on occasion, but are unlikely to see constant or standing water.
Very Wet Area
Light Traffic
VitreousGroup II(Wet)
COF 0.60, DCOF 0.42
Guest baths. Rooms where there is usually no through traffic, that may experience constant or standing water.
Medium Traffic
VitreousGroup III(Wet)
COF 0.60, DCOF 0.42
Master or family baths. Areas of through traffic or normal use that may experience constant or standing water.
Heavy Traffic
VitreousGroup IV(Wet)
COF 0.60, DCOF 0.42
Busy bathrooms and shower floors. Areas of constant through traffic or heavy use that may experience constant or standing water. Exterior decks, patios and walkways that do not experience a hard freeze (and in areas that do experience a hard freeze if the tile is frost rated).
Exterior
Vitreous (if frost rated) or Impervious2Group IV or V(Wet)
COF 0.60, DCOF 0.42
Decks, Patios, Walkways. Exterior areas that experience a hard freeze in winter.
Notes:
1. You will rarely find Group I tile at a tile store. It is usually sold for hobby and craft applications.
When in doubt about a rating, select the next higher rating. For example, if you are not sure whether your kitchen qualifies as a moderate traffic or heavy traffic area, go with heavy traffic and choose a Group IV tile over a Group III tile — just to be sure. Better sure than sorry. Almost all tile is now glazed, and almost all glazed tile rates at least Group II on the PEI wear test.
2. Some tile rated "vitreous" in the water absorption test will also work outdoors in a hard freeze climate. Look for the "Frost" rating on the package.

When Do You Really Need Por­ce­lain?

Porcelain is far too much tile for most applications, and just not worth the higher price for features you don't really need. When do you actually need por­ce­lain? Well, it depends on what you mean by por­ce­lain, but here is a rough guide.

If You Mean Waterproof, "Impervious" Tile

There is no residential indoor application that requires impervious tile. That's worth saying again: there is no indoor application that requires impervious tile. None. nada, zip, zero, zilch, bupkus. Outside, it's a different story.

Outside the House

If you are using tile on a patio or deck in the Yukon (or Nebraska), you need a tile rated for frost resistance so it will withstand the repeated freeze/thaw cycles of northern winters without cracking. Some tile rated "vitreous" in the water absorption test will stand an exterior environment in hard freeze areas — look for the frost rating. A tile rated "impervious", will almost certainly be suitable for exterior use, frost rating or not. but it does not necessarily need to be called por­ce­lain. Ignore the word "por­ce­lain", look for "impervious" or the frost rating to be sure of what you are buying.

Inside the House

Inside the house, impervious por­ce­lain is simply more tile than you need. If you examine the Application Guide, above, you will find that the best grade of tile you are likely to need is "vitreous" with a wear rating of Group IV for your floors in high traffic areas (hallways, kitchens, entries).

There is no indoor residential application that actually requires impervious por­ce­lain tile — absolutely none.

There is no glazed tile that needs to be full-bodied.

If your tile seller says different, he is a big fat liar, liar, pants on fire.

Even this level of durability is more than is needed for low traffic floors, walls, backsplashes, and other surfaces that are not heavily walked on. Semi-Vitreous and Group III are likely more than enough. If the tile is on a wall in an area other than a bath or kitchen, then most likely Non-Vitreous and Group I or Group II will work well enough, although, frankly, you will seldom find a tile rated in Group I in a tile store. You will have to go to a hobby or craft store to buy this grade.

You can, of course, buy impervious tile for inside your house. Just expect to pay more for durability features you won't need. It's like buying a car. If you need to get to work, to the store and to church on Sunday (or Friday or Saturday, as the case may be), you don't need a Ferrari. It would be nice to own one, and you can certainly buy a Ferrari if you don't mind the budget-walloping cost of a Ferrari, but you are not likely to use the extra features you are paying for, like 200 m.p.h. on the flat or zero to 100 in 3.4 seconds. For what you are going to use it for, a Chevy is car enough.

The subway tile on the walls rates “Semi-Vitreous” on the ANSI water absorption test and the unglazed hexagonal mosaic floor rates “Vitreous” with a hardness rank in PEI Group II (light duty floors).

Both are called “porcelain” by their manufacturer following the European tradition which defines any light bodied tile as a por­ce­lain.

Neither would be por­ce­lain under the American/ANSI definition of por­ce­lain, but they are both completely adequate for their respective applications and will last a long, long time with reasonable care.

The same is true of ceramic tile. The most economical approach is to buy just the features you actually need. Sure, tile rated Impervious is harder and more durable and will last nearly forever — it's the Ferrari of tile. But, do you need a tile that will last nearly forever, or can you get along with one that will last a mere 500 years or so?

If a tile is rated for the application you have in mind, it will outlast you, your house, my 1968 VW micro bus (maybe), and your great-grandchildren's great-grandchildren. Any extra durability is just a waste of money that you could be using to upgrade your faucet, buy a better bathtub, or splurge on a romantic dinner for two at Vincenzo's. Don't forget that ceramic tile found in Pompeii has lasted over 2,000 years, survived at least one volcano, and, by today's standards, is truly crappy tile.

If You Mean Light-Bodied Tile

If by "por­ce­lain" you mean a light bodied tile, then whether you need it depends on whether the tile is glazed or unglazed.

Glazed Tile

Glazed light bodied tile has absolutely no place, purpose or function in the world. We have never in 40 years of remodeling found a use for a through- or light-bodied glazed tile. Not once. Not ever.

If the tile is glazed only the glaze will show once the tile is installed, so the color of the tile body makes absolutely no difference whatsoever to the appearance of the installed tile.

A tile that is rated for the application in which you intend to use it will outlast you, your house, my 1968 VW micro bus (maybe), and your great-grand­child­ren's great-grand­children.

Any extra durability is just a waste of money …

Of course, your friendly tile store clerk may recommend full-bodied tile "just in case" it chips or cracks. And, it is true that the damaged area will not be quite as obvious in a full-bodied tile. But, this is a false economy. First, the chance that a properly installed ceramic tile will chip or crack is very remote. Beating it with a hammer will do it, but not much else. And, second, the solution for a chipped or cracked tile is to fix it. None of the many tile rsurfacing kits available on the market is perfect, but they do a better job for a lot less money than the extra cost of a roomful of through-bodied tile. Better yet, replace it with one of the extra tiles you saved and stashed in the basement.2 (You did save some and stash it in the basement, right? Right?)

Unglazed Tile

If the tile is not glazed, then it's a different story. The color of the body is the color you will see, and if you need a light colored tile, traditional light-bodied por­ce­lain may be your answer. One common interior application is mosaic floor tile which is often not glazed (to reduce slipperiness). This was a tile frequently used for bathroom floors in Victorian and Craftsman bathrooms — most often in bright white — so we use a lot of it in reproductions. Light-bodied por­ce­lain used to come primarily from Italy, and it was pricey. Now days its made almost everywhere, and the price has dropped dramatically.

The Bottom Line

So, here's the bottom line:

1. There is no indoor residential application that actually requires impervious por­ce­lain tile — absolutely none. If your tile seller says different, he is a big fat liar, liar, pants on fire.
2. Light bodied por­ce­lain is appropriate where the body will show and a light body color is desired. If the tile is glazed, however, the color of the body makes no difference. It it will not be seen after the tile is installed. So, paying extra from full-bodied or light-bodied glazed tile makes no sense whatsoever.

The Three Tile-Buying Do's and Don'ts

So, at the end of all this discussion we end up with just three simple rules for buying fired clay tile.

Don't  pay any attention to the word "por­ce­lain" on a box of tile. The term is far too ambiguous with multiple meanings. It and does not tell you anything particularly useful.

Do      read the ratings on the box. Even if there are no handy icons, the ratings are probably in the fine print somewhere. If there are none, pass it by. You do not want to buy untested tile because you have no idea what you are getting. If you have questions about a rating or whether a tile will work for the application you have in mind, ask them of the manufacturer, not the clerk. The clerk probably knows less about it than you do after reading this article.

Don't  buy a better tile than you need. If you buy an impervious tile for your shower walls, you have probably paid more for features you don't need such as very high wear and frost resistance. A semi-vitreous tile would work just as well, and most likely cost less. Of course, if you just found the tile sale of a lifetime, forget all this and splurge, splurge, splurge.

So, is it por­ce­lain or is it Ceramic?

We don't actually care, do we?

As we have seen, a tile deemed "por­ce­lain" by its manufacturer is not necessarily better, harder, more durable, more scratch resistant or even always more expensive than a ceramic tile; and if you paid more for a tile because it said "por­ce­lain" on the box, you've just been had by a marketing scheme that dates back beyond the ancient Greeks to the even more ancient Chinese.

The only two things that actually matter are whether you like the look of the tile and whether it is rated for how you intend to use it. A tile rated for the application you have in mind will work whether the manufacturer chooses to call it por­ce­lain or not.

So, if the tile salesman tries to "upgrade" you to a more expensive "por­ce­lain" tile, look bored and yawn a lot. You know that there is no practical difference between ceramic and por­ce­lain tiles. Ah, what the hell, "accidently" drop a box of tile on his toes for trying to trick you — deceivin' scoundrel that he is.

A Little Something to Take to the Tile Store

OK, so now you know how to buy tile. If you read this article carefully, you also know more than 95% of tile store clerks. So now for the piece-de-resistance, here is our handy How To Read a Tile Label & Ceramic Tile Application Guide crib sheet that you can download and print to take with you to the tile store.

Don't forget your "tile expert" testing materials: pocket knife, small shard of window glass, copper penny, small case-hardened (machinist) file and the ever necessary tap water — cleverly disguised as bottled drinking water — no one will suspect. (By the way, don't try to go through airport security or into a federal building with this stuff in your pocket or purse. At very least you will be asked a lot of personal questions by large, humorless men in blue blazers.)

Happy tile hunting. Let us know how it works out. And, don't forget leave your comment, below. Also, take a look at our other in-depth articles on remodeling topics and issues. The complete list is in our Index to Articles. Have fun. We do.

Footnotes
1. Burton, William, Porcelain, Its Nature, Art and Manufacture, B. T. Batsford Ltd., London 1906, pp. 4748. Available on line and as an e-book, courtesy Google Books.
2. For a good, well illustrated article on replacing a ceramic tile, see How to Replace a Broken Tile from Old House Magazine.

Rev. 02/132/18