Porcelain tile has become extremely popular with consumers, but there is still a lot of confusion about what porcelain is and how it should be installed. Columnist Dave Gobis examines some common misconceptions about this popular flooring product.

Porcelain tile can be problematic to drill without the proper equipment.
These drills are one of many that come as a kit. The key to longevity is keeping the drills wet at all times.


Porcelain tile is no longer a craze; it is now a normal everyday product commonly used everywhere in the home and at work. We still hear "I have porcelain," which I guess must be equivalent of saying I own a Hummer instead of a Jeep. Basically it is that same type of perception that Porcelain tile shares with typical floor tile that has absorption over .5. Porcelain, like a Hummer, is a little more heavy duty than a Jeep and has a few more bells and whistles available. In the real world, just how many really need a Hummer instead of a Jeep? Certainly very few can fully take advantage of the performance difference. With enhanced performance ceramic tile (Porcelain) comes the need for enhanced installation but many continue to treat porcelain as just another tile. From a sales perspective misconceptions about its performance and manufacturing process also continue as a common place. In doing a little research for this article I Googled "Porcelain Tile" and came back with 3, 700,000 hits. Next I entered "Porcelain Tile Problems" and came back with 2, 600,000. I was not ready for that, so I decided to do a little cut and paste Q&A for this month's article. What follows are actual excerpts taken at various websites from retailers, contractors, distributors and manufacturers. Each company is highly recognizable and the text is unaltered, their names have been deleted for obvious reasons.

With the proper equipment even fabricating intricate shapes are a breeze. Shown is one of many band saws that make short work of custom patterns.
Quote: "PORCELAIN TILE is not a glazed tile. They are the same extremely hard, durable, non-absorbent material all the way through. The tile face finishing process creates microscopic open pores (micro pores)."

This is a quagmire of sorts. Most Porcelain tile today is glazed. Glaze is a ceramic surfacing material that is used to provide a certain appearance. Glazes are a thin finish that can and will eventually wear off of the tile. Glazing today is a very sophisticated matter. Modern high volume plants have a plethora of devices on a conveyorized glaze line, such as silk-screeners, waterfalls, sprays, dry glaze dispersers, printing rollers, texturizing machines, and other devices. Some factories have 15 or more applications of glaze material on one line before firing the tile to make the tile look natural and random. It is true that polished porcelain often has exposed pores. Some tiles are treated with a clear glaze, some are not. Before grouting it is important to know if the exposed pores will harbor small grout particles. If so a sealer is recommended.

Quote: Special clays allow porcelain tile to be fired at temperatures even higher than ceramic tile, typically exceeding 2,400 degrees (F). The higher temperature results in a very dense tile. And the denser a tile, the better it resists moisture.

First and foremost, porcelain is a type of ceramic tile. Porcelain tile actually requires minerals in addition to clay. In this process is the mineral components of the tile body are milled to very small particles (like dust) and then pressed under very high pressure to form the tile body. The particles are of varying size and very small. They are then compacted under high pressure into a body that when heated in a kiln will fuse into a strong, dense, and low water absorbing body. No argument the denser the tile, the more resistant to moisture. However, the denser the tile, the hard to bond in direct surface applied applications.

Quote: Always look for a Mohs Hardness. The Mohs test is a scale of hardness developed by the German mineralogist Frederich Mohs and ranges from 1 (talc) to 10 (diamond). You should look for a 6 or 7.

A Mohs hardness is a scratch resistance test. In most tile applications glaze wear is of much more concern than scratching. When a porcelain tile is glazed it is the glazed surface that takes the wear, not the body. There are glazed porcelains on the market that only make a glazed wear rating of 2, barely residential. It is true that a porcelain body can support a harder glaze surface and result in increased wear ratings. It is not however automatic that all porcelain tiles are rated a 4 or 5

Quote: "Ceramic" or non-porcelain tiles are generally made from red or white clay fired in a kiln. They are almost always finished with a durable glaze which carries the color and pattern. These tiles are used in both wall tile and floor tile applications, are softer and easier to cut than porcelain, and usually carry a PEI 0 to 3 rating. Non-porcelain ceramic tiles are usually suitable for very light to moderate traffic and generally have a relatively high water absorption rating making them less frost resistant and they are more prone to wear and chipping than porcelain tiles.

There is little in that entire paragraph that is accurate. Clay used in manufacturing tile can be in many colors. Lets get rid of another tall tale about the color of the clay and it's affects on the performance of the tile. Relatively speaking, there is none, quality is important, not color. Coloration of the clay (which is only one of the components in ceramic tile) indicates nothing. If your plant is near a good red clay deposit, that may make it red. If your plant is near a gray clay deposit, that may make it gray. If your selling red tile body against gray tile body of course red is better, likewise if your selling gray. Then maybe you will get a company that feels (sells) white body that is better than red or gray! There are also many non-porcelain ceramic tiles that carry a wear rating of 4 and some even 5. Most non-porcelain floor tile today falls in the 1 to 5% absorption range.



Score and snap large porcelain tile?
I have found very few instances where a large porcelain tile can not be cut with a quality cutter.
Quote: To be used outdoors, we recommend the tile must be frost proof and unglazed for floor use. Make sure the absorption rate is 0.5% or less.

This basically limits all exterior installations to unglazed porcelain tile. Tile has been installed for hundreds of years, and in some instances thousands of years before porcelain tile came along. Most non-porcelain floor tile today falls in the 1 to 5% absorption range. Anything less than a 5% absorption rate can be used outside in a freeze thaw area, less than 3% is preferred. Many millions of square feet of glazed tile have been successfully installed in exterior applications.

These four quotes appear to be one of the most popular fantasies about porcelain tile

  • Porcelain tiles will not need replacement if chipped.
    Hmmm, I don't know about you but if there is a chunk of tile missing in my floor, I would want it repaired regardless
  • Extremely durable, porcelain is made of the same material from top to bottom. Even if the top chips or scratches, the mark is not visible. Porcelain tiles that imitate real stone are very popular. Since tiles vary slightly in shade and texture, it is difficult to tell porcelain from real stone.
    Most porcelain tile that has a stone appearance is glazed porcelain. The body may be the same color from top to bottom. But, if you chip the glaze you will see the color of the body, and it will not look the same.
  • A true porcelain tile has color all the way through it. If you chip a porcelain tile, the color is still there. Porcelain tile is much harder than ceramic. It's also more expensive."
    If it is glazed, you will see the body. There are also processes of manufacture that use double charging where to distinct colors of porcelain tile exist. This is typically to create a desired effect.
  • You would be advised to select a porcelain tile with a hardness rating of at least 5 even for your own home. As a porcelain tile it is the same color all the way through, so, if you do manage to chip it somehow it is less obvious.
    For residential application a group 3 is more than adequate unless you live on a sandy beach. The only difference between a rating of a 4 and a 5 is a staining test. Group 5 will withstand severe commercial traffic. I can not think of any residential application that would warrant such a tile by necessity.

Quote: There are consequences to making a tile with a near-zero water absorption rate. Because of its density, porcelain tile needs to be physically supported while the adhesive sets. Also, porcelain tile is much harder to cut. You'll need a diamond wet-saw.

Now I am totally at a loss as to what this means. Physically supported while it sets? Neat trick, I thought that is what thinset was for, silly me. As for needing a wet saw to cut porcelain tile, only if you don't buy decent tools. There are very few porcelain tiles that I have not been able cut with a score and snap cutter over the years, very few.



When purchasing new equipment such as a wet saw you need to be realistic about the size tile you will be cutting both on a straight cut and diagonal. Many newer saws are designed with this in mind. Note the clearance on the supporting arm of this saw.
Quote; Low porosity of porcelain tile presents a challenge to bonding and requires a premium two-part acrylic/latex enhanced mortar system.

This may have been true in 1975 (the quote was from a recent article) but is certainly not the case anymore. There have to be literally more than a 100 polymer modified products that will bond porcelain as well as some liquid systems. Liquid is no doubt a superior product when all things are equal but is very easy to exceed the values of liquid latex when they are not equal, at a more cost effective price.

Quote 1: Patios and porches are popular spots for tile. But in climates where freezing and thawing are quite common during the winter months, ceramic tile is not practical. Porcelain tile, which is non-porous and denser than ceramic tile, is a better choice for outdoor installation.

Quote 2: Some PORCELAIN - tiles can be used on exterior applications but be careful to ensure it is a porcelain thru body tile and not a glazed porcelain as most glazed porcelains are not freeze/thaw stable and can crack in our climate.

This is also not true as we discussed earlier in this article. I live in Wisconsin where we have many 100-plus-year-old buildings with the original quarry tile floors and entries in exterior freeze thaw environments. These were installed without thinset, membranes, latex or any other modern setting materials, just good old sand and cement. In many instances they look as good as the day they were installed. Glaze is much like glass. If your windows make it through winter, so will your glazed tile.



What kind of tile article would it be if we did not say thinset coverage is everything to an installation? How about trying one of the new specially formulated thinsets or new trowel configurations?
Quote: Ceramic and porcelain tile both are made from silica, a hard glassy mineral, but differ in how they're manufactured. Ceramic tile starts out as wet clay, and is pressed with molds into desired shapes and sizes, then fired to about 1,600 degrees. By comparison, porcelain tile starts out as a powder, and also is pressed into the desired form, but then is baked at a much higher temperature of up to 2,600 degrees, "to the point where it vitrifies, which makes it impervious to moisture," he says. Porcelain tile thus is denser than ceramic tile, which means it's less likely to break, and its frost-proof, so it can be used outdoors.

There are two major types of tile, quarry tile that is tile that is made by extrusion or wet process from natural clay or shale and tile that is made by the pressed dust method or dry method. You may ask at this point, how can a pressed dust body produce a strong tile? Well, this process is one in which the mineral components of the tile body are milled to very small particles (like dust) and then pressed under very high pressure to form the tile body. They will compact into a strong body that when heated in a kiln will fuse into a strong, dense, and low water absorbing bisque. This dust press category includes wall tile, mosaic tiles, and floor tile. Any type of tile can be glazed or unglazed. Once again, the moisture absorption rate determines whether it can be used in exterior application, not the "type" of tile.

We hope exploring some of these published excerpts has helped you become a better informed tile professional. As an industry group, we appreciate that you take the time to read articles such as this and many others to become better educated and thus separate fact from fantasy. If there are any subjects you would like to explore in future articles please let us know. We write for you and are happy to explore any tile-related subject you may choose.