New & Traditional Countertop Choices: Part 1 Natural Stone  Ceramic Tile  Porcelain Slabs & Sintered Stone 

A countertop takes a lot of abuse. In the kitchen, you put hot pans on it, cut on it, scrape and scratch at it, scour it, and spill hot liquids on it. In the bathroom, it's worse – with all the various chemicals spilled on counter surfaces – the soaps, the creams, the nail polish, the model airplane glue. Yet after years of abuse, your countertop is expected to look as good as ever – and mostly they do.

Today's countertop materials are truly miracles of modern engineering, evolving so rapidly that even if you've replaced a kitchen countertop in the recent past, you'll probably be surprised by the many options in materials and styles now available.

Natural Stone Countertops

There are very few materials more durable than stone. Cool and long-lasting, stone offers a timeless, elegant beauty that few other materials can match.

Some stones are hard and resist scratches and heat, Others are more delicate and require a lot of care and maintenance. Even the most durable stone has drawbacks as a countertop material. It has no "give" at all so that a plate, cup, or glass dropped on it is likely to shatter rather than bounce.

The stone itself can crack, break, chip and scratch. Some stones stain easily – marble, travertine, and soapstone are notorious culprits – although many believe that the visible signs of use that accumulate over time add to the patina and charm of these upscale materials.

Slate and schist are particularly susceptible to edge chipping and require special care in both installation and daily use. But, all stones will chip if hit hard enough or at just the wrong angle.

Almost any stone can be made into a countertop but the most desirable stones are those that can take a good polish to create a smooth working countertop surface.

We are not even going to try to review all of the possible stone countertops. There are far too many. We will look at just the more common offerings in regular commercial use: granite, limestone, marble, schist, slate, and travertine.

Marble & Travertine Countertops

Travertine is very like marble, just more porous and softer. Both materials have been popular since the early Greek and Roman years because they are beautiful and fairly soft, making them easy to cut and polish with relatively simple hand tools (and a whole lot of hard labor).

Frequent cleaning and re-sealing are needed to keep the materials looking new. They can be dulled by soap scum and hard water and will show white rings if wet glasses are left on the countertop for too long.

Granite Countertops

Granite is still the stone of choice these days. It is heavy, hard, and durable, very difficult to crack or chip, and will easily outlast your house.

Many varieties are very hard to stain, but regular sealing is usually recommended. We have heard reports of granite tops that do not need sealing, but we have never actually seen one, and, frankly, don't believe it. Granite, no matter how dense, is porous and any porous material can stain.

Granite comes in a seemingly infinite range of colors and patterns, with more arriving every day. On the downside, it is just about the most expensive countertop material around, rivaled only by concrete and some engineered stone materials.

Soapstone Countertops

Soapstone, eclipsed for years by granite for most of the last two decades, is making a strong comeback as granite countertops become more and more common.

The look of soapstone is timeless and historically accurate for almost any period of American architecture. It is warmer, denser, and heavier than granite.

It is not, however, nearly as hard. The primary ingredient in soapstone is talc, about the softest mineral around. It can be scratched with a fingernail but rarely are scratches more than superficial and can be removed with an application of mineral oil. More severe scratches disappear with fine sandpaper or even a scouring pad.

Unlike granite and most of the other natural stones, soapstone is almost impervious to water penetration, unaffected by acids or other kitchen chemicals, and absolutely heat resistant.

These are some of the reasons it has been the preferred material for countertops in chemical laboratories for well over 150 years. Even the hottest pans can be set on it without harm. Since it is almost impervious to liquids, it does not need sealing. But, it does stain. Even water leaves a mark. Soapstone aficionadoes don't mind – it's all part of the patina that gives soapstone its unique look. Stains are easily removed, but it is bothersome to keep it looking new and unblemished. So, those who are not fans may want to stay away from it.

Classic soapstone from New England is light gray to almost black, often with a greenish tinge, but the material can range from light brown to terracotta depending on its source and treatment. Very little soapstone is now quarried in the U.S. Most comes from Brazil.

A soapstone surface darkens naturally with age or when exposed to water or oils. To darken it evenly, soapstone can be treated with food-grade mineral oil. The darker it gets, the more light grey or gray-green veins stand out adding to soapstone's appeal. New "dry wax" coatings have been developed that replace mineral oil and last longer, but are, of course, considerably more expensive. Many soapstone fans, however, simply let it age naturally over the years, adding a patina of wear and use. But, renewing soapstone is easy – simply sand away the old surface for a brand new look. Repeated restorations are possible over many years.

Limestone Countertops

Limestone is another sedimentary rock composed mostly of calcite. Like marble and travertine, Limestone is very soft and easy to damage with acids and abrasion. The most frequently used limestone for countertops is dense and fine-grained. Examples are Jerusalem stone that is known for its consistent texture and even color and Belgian and French bluestone.

Limestone is available in the usual earth colors: brown, beige, yellow, gray, and black. The bluestones have a bluish tint, which makes them rare and sought-after. Look for consistency in color and even texture throughout the stone. Some limestones are dense enough to be polished to a high gleam, but the usual finish is a low luster, hewn stone look.

The stone is soft and porous. It retains moisture and can stain irreparably. Like marble and travertine, it can be damaged by mild household acids like lemon juice, vinegar, and tomatoes which can dissolve the calcium in the stone. It can also be easily scratched and is not usually recommended for busy working surfaces such as in food preparation areas, or any place a knife is likely to be used. But as an accent countertop or backsplash, it can be truly gorgeous.

Slate and Schist Countertops

Most true slate is used for floors, usually in the form of tiles. It is too soft for countertops.

The material used in most "slate" countertops is actually schist, a. harder, finder grained metamorphic rock quarried mostly in New England and upstate New York.

Schist is dense and like soapstone, nonporous. Liquids cannot penetrate the surface of the stone, so it will not stain. It contains little calcium, so it is unaffected by acidic liquids like wine and fruit juices. Hot pans can be placed on it without the risk of damage.

It comes in an array of earth tone colors: light gray to charcoal, various shades of purple and green, and soft red in naturally streaked and plain patterns. Stylistically it is a more subdued option for countertops. It does not have the dramatic grain and color effects of granite. For reproducing a heritage kitchen, however, it is authentic and consistent with any era from early Victorian to the present.

Maintenance is minimal. A wipe-down with a damp cloth or sponge is usually sufficient with an occasional cleaning with a mild detergent. While the material does not need sealing, some owners wax or oil the surface to give it a wet look that deepens the color and enhances any grain effect.

Slate is brittle. It can be chipped at corners fairly easily, so most installers round off corners to reduce the risk. A sharp blow from a heavy object such as a cast-iron skillet can crack the material.

Ceramic Tile Countertops

If any countertop material is available in even more colors and patterns than laminates like Formica^®, it must be fired clay tile.

Tile for countertops has an impressive history going back to the ancient Greeks and Persians, even farther. To give you an idea of the durability of tile: Tile work in the Roman city of Pompeii was complex and intricate, survived one volcanic eruption, and has lasted for 2,000 years. And, by today's standards, it is not even a very good tile.

Ceramic tile is made from a special clay called kaolin and silica (sand). Clay tiles are "fired" – heated in a kiln to a very high temperature to harden the kaolin and turn the silica into quartz glass.

High-quality water- and wear-resistant tile is fired longer at a higher temperature so it is harder, denser, and more impervious to water than "softer" tiles.

A glazed tile has been surface coated on the top side with glass which bonds to the clay when the materials are fired. Tiles may be glazed or unglazed. Unglazed tile needs to be treated like stone. It must be sealed, and the sealant must be renewed every year or so.

Glazed tile may be treated like glass – a surface that needs almost no maintenance. Unlike glass, however, tile is very difficult to break.

Not every tile is suitable for use as a countertop. Soft, thin tiles designed to use on walls are not good countertop material. Hard tiles rated for use as flooring are more than adequate.

Grout is a problem for a lot of people who otherwise think tile would make a beautiful surface for countertops. Everyone has heard the stories: grout cracks, falls out, stains, gets dirty, harbors harmful bacteria, and needs to be cleaned and sealed regularly. All of this is true with cement-based grouts. But there are other kinds of grout.

Its one drawback is that it has to cure for up to 72 hours before being used (7 days around a sink), which can be a nuisance. It is also more expensive than cement-based grouts. But we think the extra expense is worth the saving in maintenance over the years. You have to specify urethane, otherwise, your tile installer will probably use the older, cement-based, formulation.

It is also possible to lay tile without grout. The edges are butted together, a process called close-setting. Ordinary tile may be close in finished size but is rarely exact due to the way the firing process shrinks tile unevenly. So, a grout line between tiles is normally required even if the grout line is a very narrow 1/16" or so. Close-setting requires a special "rectified" tile that has been cut or ground so that each tile is exactly the same size.

Glazed tiles are already permanently sealed with glass so sealing is not required. Urethane and epoxy grout does not need to be sealed. But, cement-based grout lines must be re-sealed periodically even in glazed tile. Grout and tile sealant is nothing more than a special coating containing a high percentage of silicon. It is usually applied with a brush or sponge and wiped off with a soft cloth. Nothing to it, really. It's not the sealing that is burdensome, it's the cleaning and de-staining before the sealing that people do not like.

The cost of tile ranges so widely that it is both the least expensive and most expensive countertop material. Some specialized imported tiles cost hundreds of dollars per square foot. Yet you can buy a perfectly acceptable tile on sale from time to time for $1.50 s/f. So it is possible for a customer on a budget to use tile -- just stay away from anything made in France or Italy.

Porcelain Slab and Sintered Stone Countertops

Porcelain slabs and sintered stone are not new materials. In fact, they are very old materials in a new guise – nothing more than exotic than ceramic tile in a new, larger format.

Porcelain slabs are typically sold by their makers as super-sized tile.

Sintered stone manufacturers are more likely to describe their material as an artificial stone and are less likely to glaze the material.

It is not stone, however. It is a ceramic made from clay, more akin to a brick than it is to stone.

Porcelain Slab Countertops

Tile makers have been experimenting with larger format tiles for decades.

Tile in larger sizes is hard to manufacture because the material tends to cup, curl, and twist when heated to temperatures of up to 2,500°. The larger the format, the more risk of deformation.

Tile makers perfected a flat 24" x 24" tile in the 1990s by adjusting the tile mix, using less water and special additives, and varying firing temperature and times. The larger format tiles generated a renewed interest in tile countertops since grout lines could be minimized using the larger format tile.

In the early 21st century even larger tiles were created – up to 48" formats. These made possible the faux wood strips popular as replacements for strip wood flooring in kitchens, baths, and mudrooms with more durable ceramic tile without sacrificing the wood look.

Now ceramic tile has gotten so large that a single tile can cover an entire countertop, eliminating grout lines altogether. In the industry, very large format tiles are no longer called tiles, they are called slabs, sheets, or veneers depending on the thickness of the material.

Early slabs were indeed slabs, up to 3/4" thick, heavy, and very expensive. As the technology of firing large formats improved, the material got thinner. Veneers are now available as thin as 1/8" (3mm).

More typical, however, are 1/4" (5.6mm) slabs – the thickness of ordinary floor tile. They are called "thin slabs" or "sheets."

Very large format ceramics are available in up to 12' lengths and as wide as 5' – and getting still larger as the technology continues to be perfected. Five feet wide is about the limit right now, however, until kilns are built that can handle wider sheets.

Veneers and sheets have no structural strength and need to be supported by a plywood substrate just like laminate materials such as Formica^®. The sheets are bonded to the substrate with a modified thin-set adhesive like the stuff used to set ceramic tile. The strength of the assembly is provided by the substrate under the slabs. The thin sheets and veneers are merely the surface finish.

Some manufacturers back their sheets and veneers with fiberglass to make them less likely to crack in handling, and some sheets are made with additives that leave them somewhat flexible. A few can even be bent around gentle curves without cracking, which increases their design potential.

Like glazed ceramic tile, por­ce­lain slabs can be top-coated with a glaze composed primarily of glass. The glaze bonds to the underlying ceramic as the materials are fired.

Glaze is impervious to liquids and unfazed by even the hottest pan (although every manufacturer recommends against putting hot pans on their por­ce­lain slabs). It needs almost no maintenance. The glaze is difficult to scratch or mar, chip, or crack, but if damaged, it cannot be repaired.

Unglazed slabs are somewhat porous and are sealed at the factory to resist staining. All slab manufacturers claim that once factory-sealed, the slabs never need re-sealing, but we take that with a fair-sized grain of salt. The material is very dense and minimally porous, but it is not entirely pore-free.

Any porous material can stain, and "never" is a long, long time. The material has no track record that proves it will not eventually need to be re-sealed from time to time. Check back in about 30 years. We'll know for sure by then.

Slabs can be made in almost any pattern and color. Some even emulate metal. But, patternless solid colors and simulated stone seem to be the most popular looks. Patterns in thicker slabs can go all the way through the material. So, any veining or stone pattern continues around the edge, making it look more like real stone.

In thinner sheets, the pattern is applied only to the surface. The material requires some sort of edge treatment, of which there are many.

A por­ce­lain slab can be an excellent choice to get the look of a fragile stone like marble, travertine, or limestone without the maintenance these stones require. In addition, unlike these calcareous stones, slabs shrug off acids, even strong acids, without damage and cannot be scratched except with a determined effort. The natural calcareous stones scratch easily.

Sintered Stone Countertops

The difference between sintered stone and por­ce­lain slabs is that there is almost no difference between sintered stone and porcelain slabs.

Sintered stone, like por­ce­lain slabs, is nothing more innovative or exotic than large-format ceramic tile. It is, in reality, just por­ce­lain slab by another name.

But, that has not stopped sintered stone manufacturers from hyping the material as "new and innovative" and the latest and greatest technological advancement in countertop surfaces – a step up from por­ce­lain slabs.

According to one manufacturer, what makes sintered stone better than por­ce­lain slabs is the careful choice of "natural materials" that go into sintered stone:

First are granite minerals such as quartz and feldspars, which provide hardness and strength. Second are silica and glass minerals, which add chemical stability. Third are clay minerals, which contribute adhesive properties and whiteness. Fourth, natural mineral pigments of different types can be added to create different colors or chromatic properties in the final product. ^Note 1

Another adherent suggests that it is the manufacturing process that distinguishes sintered stone from por­ce­lain slabs.

Sintered stone is manufactured using recent technological advancements which mimic the processes which form natural stone… Minerals … are … subject[ed] to extreme heat and pressure, just like they would be deep in the earth's crust where granite is formed. When the process is finished, the particles are bonded together permanently, without the need for resins or bonding agents. ^Note 2

In fact, there nothing here that is new or could be considered any sort of "technological advancement."

The fabulous "natural" materials used in sintered stone are nothing more exotic than the same old clay, sand, quartz, and feldspars that have been used to make ceramic tiles since the Stone Age – more than 5,000 years and possibly as long as 10,000 years ago. So, again, absolutely nothing new here.

The manufacturing process that mimics the extreme heat and pressure that form natural stone is the well-established dust-press (or dry-press) method of making ceramic tile. It has been around for the better part of two centuries, first patented in 1853 by British engineer, inventor, and patent law reformer, Richard Prosser.

Read the very interesting Prosser biography: Prosser The Engineer: A Forgotten Birmingham Genius by Susan Darby which can be downloaded in .pdf format, free of charge.

In the dust-press method, tile starts out as a slurry of kaolin clay, feldspar, silica (sand), quartz, and any additives the manufacturer believes will make a better tile. The slurry is about 30% water. The mixture is called the "slip" or "body slip".

Once the materials are well mixed, the slip is placed in a dryer to remove most of the water leaving a slightly moist powder that can be stored until needed.

To make tile, a porcelain slab, or a sintered stone panel, the damp powder is pressed in a mold at a very high pressure to compact the material and form what is called a bisque. The pressing removes almost all remaining water and any air or gas trapped in the material. The bisque is now very dense and compacted.

Next, it is dried again to remove all but a trace of moisture. The water has done its job, helping the particles stick together. It is no longer needed.

The bisque or "green tile" is fired for as long as 72 hours in a kiln that reaches 2,500°F (1,371°C). At this temperature, the clay and feldspar in the bisque soften and begin to bond together to produce a material called mullite.

Sintering: The process of softening a material to a point at which it begins to bond without turning it into a liquid state is called "sintering." The resulting bond is at a molecular level and very strong. It is also the source of thw word "sintered" used to describe the material.

At about the same time that sintering begins, the silica in the mix bonds with oxygen to turn into cristobalite, a form of quartz (silicon dioxide) that flows into the gaps in the mullite, sealing the material so water and other liquids cannot penetrate. This process is called vitrification.

Vitrification: from Latin vitreum, "glass" via French vitrifier, is the process of transforming a substance into a glass.

Mullite gives ceramic material its strength. Vitrification makes it stain- and water-resistant. How resistant depends on how much vitrification occurs. If vitrification is almost complete, the material is dubbed impervious to liquids using a rating system common in the tile industry.

So, when all the hype is stripped away, despite the word "stone" in its name, sintered stone turns out to be not a stone at all – not even a stone composite. It is nothing more innovative than a high-quality, very large format ceramic tile.

A more accurate description would be "sintered clay." But, who would buy sintered clay? Sintered stone is much sexier.

What is actually new to the process of manufacturing sintered stone (and porcelain slabs) is the chemistry of preparing the materials which has gotten more precise, the presses that have gotten larger and more powerful, and kilns that have gotten hotter. But, as far as an actual technological revolution, there is none.

Sintered stone is available in widths up to 5' and lengths up to 12', just like por­ce­lain slabs.

Also, like por­ce­lain slabs, sintered stone is available in several thicknesses down to about 1/4". A variety of colors is available, some without a pattern but many that simulate stone, especially marble. In fact, if you are thinking natural marble for your kitchen or bath, take a good look at porcelain slab or sintered stone. For about the same cost you will get a material that is much more durable and virtually maintenance-free.

One difference between porcelain slabs and sintered stone is that makers of porcelain slabs are more likely to use a glaze to protect the material while sintered stone-makers seem to prefer an unglazed ceramic – more in keeping with the illusion that the material is actual stone.

Porcelain and Ceramic Tile: Is there any real difference? For more information about por­ce­lain and other ceramic tile, and details of how tile (including por­ce­lain slabs and sintered stone) is made, see Porcelain vs. Ceramic. Is There a Difference? and How to Choose Ceramic Tile.

More Countertops…

We cannot get all of the many varieties of countertop material on one page, so to learn about other countertop materials, continue to the next section. (Continue).

Footnotes:

Rev. 10/11/23w