KNOW HOW

Counter Intelligence: Weighing the Virtures of Marble vs. Granite

By Jeanne Huber
Special to The Washington Post
Thursday, July 21, 2005

QI'm trying to decide between marble or granite kitchen countertops, but I've heard marble is more vulnerable to stains. And is honed stone more vulnerable still?

A Stone salespeople who don't want to deal with grumpy customers generally recommend granite because it's likely to stay in mint condition even with sloppy housekeeping, while marble countertops can become scratched, stained and dulled even if you're reasonably careful. Yet this hasn't stopped cooks in Italy from rolling their dough on marble for centuries. And it needn't stop you from installing it in your own kitchen -- provided you know what to expect and want that result.

The three main issues -- staining, dulling and scratching -- are easiest to understand if you know a little about the underlying geology. Marble started out as limestone, which is basically calcium carbonate (usually from shells) plus silt on ocean floors. As the Earth's crust buckled and shifted, the resulting heat and pressure softened the limestone and caused it to recrystallize as a harder, denser material.

Marble stains when watery or oily liquids seep into the microscopic spaces between the crystals; the crystals themselves are impervious. By applying a penetrating sealer, you can narrow the voids and make them so small that liquids can't flow through by capillary action. Individual water molecules can still fit through, however, so any moisture within the stone can evaporate, which is good. But liquids can still sink in, although not as quickly, so the stone can still stain. The sealer gives you maybe 24 hours, versus 30 minutes, to wipe up spills before they lodge too deep for you to wipe them away.

These sealers are so effective that, today, stains are probably the least of your concerns with marble, even though it's the issue you may hear most about. "Staining isn't as big an issue as people believe," says Chuck Muehlbauer, the technical expert for the Marble Institute of America, an industry group. "I field trouble calls from the whole nation, and I get maybe one call a week about staining of marble."

If marble does stain, you can usually remove the marks or at least partially lift them by applying a poultice -- an absorbent material plus a chemical that will dissolve the stain and cause it to flow into the absorbent material. There are ready-made products, which you spread on like peanut butter and cover with plastic for a day or two. Or you can make your own using a napkin, blotter paper or whiting as the absorbent material plus a liquid, such as hydrogen peroxide or acetone, that works on the specific spill. (See italic note on where to get recipes.)

The dulling issue is not so easy to deal with. Because marble is a carbonate, spills of lemon juice, vinegar or other acids trigger the same fizzy reaction that occurs when you swallow a Tums (also calcium carbonate) to deal with stomach acids. On a countertop, the reaction eats into the marble on the surface and leaves a dull mark. There is no way to reverse this once it has occurred, and sealers can't help because they only fill spaces between the crystals; they don't coat the surface crystals themselves. (A surface coating would do this, but it would leave you with a plastic work surface.)

Although it may be technically possible to sand down a dull area and repolish the marble, if you opt for marble countertops, you should be willing to accept dull spots. Like scratches on a new car, the first few will probably bug you far more than the many that are likely to accumulate over time.

To make etching less noticeable, consider buying marble with a honed surface rather than one that is highly polished. This evenly dull surface, which is what cooks in Italy always have, also dramatically ratchets down the formal look that polished marble conveys. But be aware that honed surfaces are a little more likely to show stains than polished ones. The stone itself doesn't stain any more readily, Muehlbauer says, but when the surface isn't reflective, color differences are more noticeable.

As for scratches, your best bet is to deal with a company that really knows stone. Although geologists have a fairly narrow definition for marble, the stone industry today markets a wide array of stones under this term. "Marble" may be almost any stone capable of taking a polish. Some are definitely unsuitable for kitchen countertops, while others work quite well. The Marble Institute of America has a rating system, A through D, that identifies which marbles are hardest and least porous, but much of what's offered for countertops isn't rated. Muehlbauer recommends asking the vendor which of the available marbles are most suitable for kitchen countertops. If you're not sure you're getting good advice, get samples of several types you like and do a little scratch test with a pocketknife.

Marble that is nearly pure white often is more difficult to scratch than marble that is highly colored or streaked because the colors result from impurities such as clay or silt that were in the original limestone. But pure white marble is, of course, most likely to show stains.

And what are the issues involved with granite? None -- except that it's everywhere. If you want your countertops to stay looking new, join the crowd. If you love the warm ambiance of antiques, go with honed marble.

For a brochure on how to treat spills and stains on natural stone surfaces, including marble, send $1 and a self-addressed, business-size envelope with a 37-cent stamp to the Marble Institute of America, 28901 Clemens Road, Suite 100, Cleveland, Ohio 44145. Or click on "stone tips" at the Web site of the National Training Center for Stone and Masonry Trades,http://www.ntc-stone.com.

For a brochure on how to treat spills and stains on natural stone surfaces, including marble, send $1 and a self-addressed, business-size envelope with a 37-cent stamp to the Marble Institute of America, 28901 Clemens Road, Suite 100, Cleveland, Ohio 44145. Or click on "stone tips" at the Web site of the National Training Center for Stone and Masonry Trades,http://www.ntc-stone.com.

For a brochure on how to treat spills and stains on natural stone surfaces, including marble, send $1 and a self-addressed, business-size envelope with a 37-cent stamp to the Marble Institute of America, 28901 Clemens Road, Suite 100, Cleveland, Ohio 44145. Or click on "stone tips" at the Web site of the National Training Center for Stone and Masonry Trades,http://www.ntc-stone.com.


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