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Ask the Editor: Sealing Granite

A kitchen with split-level stone countertops.

How Do You Maintain Stone Countertops?


Question: "We just got new granite and marble countertops and were told that they have been factory sealed. Should we use an additional sealant? How often do they need to be resealed?"


Answer: First, find out what kind of sealant the factory used on each stone. Your installer and/or fabricator can give you this information. Some sealants need to be reapplied every six months to a year; others can last for several years. The porosity of the stone as well as its usage (counter, floor or wall; kitchen, bathroom or other room; amount of traffic or food preparation) also will affect the length of time between treatments.

You can do the sealing yourself or hire a professional-if the stone has become stained or needs to be refinished or rebuffed, the latter might be the wiser choice. 


Sealing Granite Counters in the Kitchen

All natural stone is porous, which means water, spaghetti sauce, cooking oil and other liquids could seep into and stain it. In addition, acids-whether found in citrus fruits or household cleaners-have a corrosive effect on stone. That's why when it comes to natural stone kitchen counters, most pros recommend using a non-toxic, food-safe penetrating sealer or impregnator.

Although granite is a hard substance that resists most chipping, heat, stains and scratches, it can still be damaged. Kelly DaSilva, president of La Pietra Custom Marble and Granite in Connecticut, takes a strong preventative approach to stone care by using two coats of sealer and a resin treatment. It makes the price of the stone higher for customers more, but reduces maintenance labor and costs in the long run.

DaSilva recommends StoneTech Professional BulletProof sealer, which the manufacturer says lasts three to five years for interior surfaces. With two coats, DaSilva says homeowners only need to reseal every six years. The factory-applied resin treatment helps to strengthen the granite and enhance its beauty."Resin treatment adds 35 percent extra to the cost, but it covers all the natural pits and fissures," says DaSilva. "That's why you don't want to use abrasive cleansers. They eat the seal and treatment, and damage the finish."For daily cleaning, she recommends using Rock Doctor or a similar product designed specifically for stone care. 


Avoid Marble in High-Use Areas

Marble is much softer and less durable than granite, susceptible to chips, scratches, stains and burns. In fact, DaSilva, like many stone experts, prefers to avoid installing marble in kitchens.

"You have to be more careful with the marble," explains DaSilva. "Make sure you don't get acids on it, they will burn into it. It's easily scratchable. I never recommend marble for kitchen countertops-keep those fine surfaces for bathroom surrounds and other areas."

Still, many homeowners can't resist marble's beauty, and it's a great surface for working with dough. If you're going to put marble in the kitchen, DaSilva says you should be especially careful to keep vinegar, citric acids, household cleaners and knives well away from it. Marble requires more frequent sealing than granite. 


Regular Cleaning and Spills

The Marble Institute of America recommends the following regular care for granite and marble counters: 

  • Clean surfaces with mild, non-oil-based detergent or stone soap

  • Thoroughly rinse and dry the surface after washing

  • After food preparation, clean up with a sponge or cloth and warm water 

  • Do not let spilled ingredients sit overnight

  • Blot all liquid spills immediately 

  • Don't wipe; it will spread the spill 

  • For wine, blot with a paper towel and then flush the area with warm water and a non-petroleum-based soap; rinse several times, then dry with a soft cloth


  • Protect counters with coasters, trivets or placemats; this is especially true for calcareous stones such as marble, limestone or travertine-alcohol, citric juices and other common foods can easily etch or dull these surfaces, while hot cookware, ceramic dishes and silverware will burn or scratch them


The institute also says homeowners should avoid cleaning with any of the following:

  • Vinegar, lemon juice or other naturally acidic substances 

  • Cleaners that contain acid, such as bathroom cleaners, grout cleaners or tub & tile cleaners 
  • Abrasive cleaners such as dry or soft cleansers, scouring powders or creams;  they can scratch the stone 

  • Using a mix of bleach and ammonia, which creates a toxic and lethal gas; you can use a solution of ½ cup ammonia to 1 gallon of water to remove soap scum, but be aware that frequent use of ammonia eventually dulls the stone