Granite, Quartzite, Travertine, Marble, Onyx – all natural stones that come across as tough, but in reality have natural weaknesses. The one weakness they all have in common is porosity, which means that they are susceptible to absorbing liquids. Each type of stone varies in porosity, but every stone is somewhat porous. If left unprotected, most natural stone will stain from simple spills, sweating glassware, drippy soup spoons, spattering grease, citrus juices and pretty much any liquid that is commonly found in the kitchen. This blog delves into how to protect your natural stone, especially by properly using a sealant.

Do You Need a Sealant? 

The general rule is that the lighter the granite or stone, the more prone it is to staining and water spotting. The exception to the rule is black granite. Most dark granites are not very porous and as a result, typical sealers won’t work on them and are generally not required. If left to sit for an extended period, however, acidic liquids may still etch black granites, leaving unattractive white marks.

Sealant Facts

Granite sealer is a simple, relatively inexpensive product. Most sealers used on granite and other natural stone are impregnating sealers. They usually contain a solvent and a resin, and work by making the granite less porous. When applied to the stone, the water-soluble solvent component of the sealer works to carry the resin component deep into the stone until the pores are full of resin. Meanwhile the solvent evaporates. The sealer essentially fills up all the microscopic pores in the stone so that it can no longer absorb liquids that cause staining and water marks.

Sealers vary in quality and some don’t penetrate the stone. If a person wants to save money, they might go to a big box store and buy a sealer off the shelf. There are a variety of very inexpensive sealers on the market, but it pays to look at the instructions carefully. Some sealants need to be reapplied every six months. Also, it’s important to look for an impregnating sealant that will penetrate the stone and fill up the natural pores. Surface sealers only cover the top of the stone, and may need to be applied multiple times, diminishing the appearance of the natural stone, and also offering less protection against stains. Surface sealers are not recommended for most natural stones.

Many common sealants need to be reapplied every few years. The frequency of reapplication depends on the type of stone, and the degree of wear and tear on the countertop. There’s a simple test that homeowners can perform themselves to see if their countertop needs to be resealed, or sealed at all in the first place. Some stones, especially black granite, may not need to be sealed. To perform the test, get a timer and about a quarter cup of water. Pour the water on the counter in a discrete location and use the timer to measure how quickly the water absorbs. If the stone absorbs all the water immediately, the stone needs to be sealed using two or more layers and sealant should be applied annually, if using a regular sealant. If the water absorbs in 4 to 5 minutes, the stone should be sealed using multiple layers and reapplied every three to five years, depending on the results of another water test. If the water absorbs in ten minutes, only a single layer of sealant is needed and it could be several years before another coat is required. If it takes 30 minutes or longer for the water to absorb, a penetrating sealer should not be applied.

Does it Really Have a Warranty?

Some of the best sealers on the market come with 15-year warranties. Many of these are not available at big box stores and are usually applied by fabricators who have been trained to properly apply the product. The 15-year sealers typically use a finer resin that creates a chemical bond with the stone as it sinks into the pores. One product – Dry Treat – claims that the molecules in its sealant are 400 times smaller than its leading competitor’s and that the product penetrates deeper and fuses to the stone through a chemical reaction for long-lasting protection. Homeowners can purchase these higher-end sealers on the internet, but they often don’t come with the warranty unless they are applied by a professional.

What Sealant Doesn’t Do

What sealer does not do is protect stone from scratches, dings and etches. If you cut a tomato directly on the surface of a granite countertop, you will likely scratch the surface with the sharp blade of the knife. Drop a large pan, and the countertop might dent or chip. If you spill a gallon of lemonade on the countertop and fail to clean it all up within an hour or so, some of the acid from the lemon could eat away at the sealant and even etch the surface of the stone. Whether that happens and how bad the scratch, dent or etch, depends on the hardness of the stone. Quartzite is harder than marble, for instance, and will be less likely to scratch, dent or etch from major kitchen blunders.

The Dos and Don’ts When it Comes to Protecting Natural Stone

All natural stone surfaces require periodic care, no matter how hard the stone or how effective the sealer is. Never use abrasive or acidic cleaners on natural stone surfaces, because the abrasive could scratch the granite and wear off the sealer. Acidic products, such as those that contain lemon juice, vinegar, bleach or ammonia, can cause a chemical reaction with the granite, creating what is known as an etch. Etches appear as white blemishes on the stone surface. Sealers cannot prevent etches.

To properly care for sealed granite, all it takes is a little common sense and attention to detail. Here are some basic tips:

  • Use only used soft, non-abrasive cleaning cloths or sponges
  • Wipe up all spills within 24 hours
  • Immediately wipe up any acidic spills, such as lemon juice, orange juice, soda, liquor, etc.
  • Immediately wipe up spills that could stain, such as wine, oil, grease, beet juice, artificially colored drinks, etc.
  • Use coasters to avoid watermarks from sweating glasses, especially on softer stones such as marble and limestone
  • Use placemats to avoid food stains and sticky, hard to clean messes
  • Don’t put hot pans directly on a cool countertop, especially in cold weather. Use trivets and pot holders
  • Avoid dropping heavy objects directly on top of the countertop, or on the edge of the countertop
  • Use cutting boards to chop and prepare foods. Don’t use a knife directly on the surface of the stone