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How Sealing Natural Stone Protects it from Staining, Water and Salt Damage, Freeze Thaws, and Mold Growth

sealing natural stone

Natural stone countertops and floors continue becoming more and more popular every passing year. And it isn’t a wonder either! Natural stone not only gives your home a distinctive, classic appearance, its durability also adds value to your home. Nevertheless, if you don’t take proper care of your natural stone, you’ll spend time and money needlessly on removing stains and fixing damages instead of enjoying your home’s new addition.

Sealing your natural stone surfaces is vital for preserving its appearance and safeguarding it from inadvertent stains that may occur. Since the surfaces of natural stone are porous, they absorb oils and liquids easily. A sealer safeguards the natural stone surfaces from absorbing liquids. As we all know, accidents are unavoidable. This is where sealer plays a vital role.

How Does Sealing Work?

Sealing your natural stone surfaces fills the pores with a transparent, impregnating sealer that doesn’t change the appearance of the stone surface. Nevertheless, the sealer allows you to clean up the surface swiftly. Thus, you prevent the surface from becoming permanently stained, damaged and etched. If you maintain your natural stone surfaces properly, the sealer will last for some years. Eventually, it will break down, and you’ll have to reapply it.

Although sealing natural stone surfaces is a vital step in the installation process, it’s often overlooked by the contractor. Sealing your natural stone surface isn’t difficult, and you can do it yourself. It’s best to seal your natural stone soon after installation to safeguard it from unwanted stains.

Why Should You Seal Your Natural Stone Surfaces?

Since natural stone is porous, it’s vulnerable to stains and damage. The absorbency of some stones is greater than that of others. Nevertheless, the most recent sealer technology makes it easier for maintaining your stone by minimizing or eliminating common problems such as, mold and mildew, water- and oil-based stains, rust, bacterial growth, cracks from freeze-thaw, etc.

Types of Sealers for Natural Stone Surfaces

Impregnators and Film Formers are the two types of natural stone surface sealers. Impregnators are essentially sub-surface sealers that safeguard the natural stone surface from within. They don’t alter the appearance of the stone surface. Impregnators protect the surface of the stone from water- and oil-based stains by letting out vapors.

Film formers, visible topical coatings, have a matte or gloss finish. They alter the appearance of the natural stone surface. Film formers create a barrier and aren’t vapor-permeable (breathable). They are problematic for natural stone because they lock in moisture, causing mold, efflorescence, and rust. Film formers can also peel, scuff, chip, yellow, and wear away. Nevertheless, film formers possess superlative esthetics and make even a dull stone look glossy.

How to Find Out if Your Stone is Already Sealed?

Just do a simple test by pouring plain water about 4–5 cm in diameter in many places on the surface of the natural stone. Let the water stand for four to six hours. After every hour, check the stone surface to determine if it’s darkening at the spots where you’ve applied water. If the stone surface darkens, it indicates that the surface is permitting water in. You need to seal the surface. If you’re in doubt, sealing the surface is recommended.

What’s the Dwell Time Between Coats of Sealer?

In case your natural stone surface requires a second coat of sealer, the dwell time between the first and second application will differ. This is due to the different absorbency characteristics of diverse natural stone surfaces. If the surface is more absorbent, it takes less time for the first coat to penetrate. In case the first application hardly penetrates the surface, a second coat isn’t necessary. The normal dwell time is between 15 to 30 minutes. Do not permit the sealer to dry. The quantity of sealer needed for the second coat is much lesser than the quantity needed for the first.

Sealing Natural Stone Doesn’t Prevent Scratching and Chipping

Sealing your natural stone surface doesn’t provide a bulletproof shield against scratching and chipping. Sealing is comparable to car wax. And having your car waxed offers no protection against scratches and dents. Likewise, if you drop a stack of frozen steaks on your granite countertop or roll a desk chair on your travertine floor, no amount of sealer will prevent them from getting damaged.

Sealing Outdoor Natural Stone Surfaces 

Outdoor elements can be extremely harsh on your natural stone surface. Pollen, dirt, and ultra-violet rays affect it adversely. If you are intent on preserving the natural stone surface outdoors, sealing is the most practical option. Sealing protects your outdoor natural stone surfaces against chemicals, pollutants, rain, snow, oils from trees, and all the grime associated with an outdoor barbecue.


If you like the appearance of your natural stone products now and want them to retain their pristine condition, sealing your natural stone surface is the best defense. But if you want your outdoor natural stone products to be shaped by the elements, then you can let them remain as they are. Determine your personal appearance as well as maintenance objectives first. Then, enquire a stone professional to recommend what’s necessary to meet them.

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