3 Myths about Sealing Granite and Marble

By Ryan Burden,

The topic of sealing granite and marble countertops, floor tile or any natural stone surface invariably creates questions, concerns and confusion in the minds of consumers, homeowners and sometimes even those working in the stone industry.

Honestly, it’s no surprise when misleading, incomplete, conflicting, or incorrect information is passed around over and over… the truth gets twisted.

Let’s examine the top 3 myths about sealing granite and marble and clear up the confusion.

Myth #1: A Sealer Must Be Applied To All Natural Stone

The most common claims I come across regarding sealing granite countertops, marble and natural stone are:

  1. “Granite countertops must be sealed.”
  2. “Granite must be re-sealed every year.”
  3. “Marble stains easy.

This myth is false. The above claims are misleading
in most cases and downright false in many others. The problem here is over-simplified “general” recommendations.

We all want easy explanations and simple rules, but these statements imply that sealing granite and marble is necessary in every case and that all stone is exactly the same.

After hearing or reading such inaccurate statements over and over the consumer naturally fears a sealer must always be applied. If not applied, a stain will permanently ruin their beautiful and expensive countertop or floor tile.

The truth is that most granite countertops will benefit from application of a sealer; however, many varieties are super-dense with low rates of absorption and don’t ever need sealing. The same can be said of marble and travertine.

It is possible to stain marble; however, marble is rather dense and actually does not stain easily. This is particularly true when polished. Of course, marble will “etch” easily, and this is where the confusion lies. People confuse an etch mark for a stain and conclude “marble stains easy” when in truth it does not.

Application of a sealer is unnecessary when the stone is naturally stain-resistant. In fact, attempting to do so will generally result in a tricky problem discussed later in this article. Perform the simple “Water Drop Test” to determine if or when to apply a sealer to any stone installation.

Myth #2: Sealers Form an Impenetrable Shell

A common misconception is that marble and granite sealers form an impenetrable shell or film over the stone shielding it from any and all damage.

This myth is not true, but explains why homeowners are often surprised and frustrated when they etch a sealed marble countertop or floor tile.

The misconception is likely based on a general definition of the word and assuming that a “sealer” acts to “seal off” the countertop surface from the environment. Well, this is not how standard impregnating sealers work.

A granite sealer limits absorption to resist staining. The sealer “impregnates” the stone with a resin to fill the pores creating a barrier just below the surface. The remaining water or solvent base of the sealer evaporates as the resin hardens and cures.

By decreasing the rate of absorption, the resin-barrier allows more time to clean the spill before the liquid can penetrate and stain.

Stains can still occur if a liquid remains on the surface long enough. The sealer resin can never entirely fill the stone pores, and the barrier is just below the surface. With prolonged exposure, a surface stain can develop, or the substance may begin to leak past the barrier.

Staining a sealed surface is a rare occurrence since most liquids will evaporate before penetrating, but it is a possibility. For example, a leaky bottle of olive oil left on the countertop.

Stone sealers will not prevent chemical damage. Again, since the “sealer” does not form a film to “seal off” the surface, etching can still occur upon contact with corrosive substances on calcite-based stones like marble and travertine.

All resins can break down over time, which is why periodic resealing is necessary. The type and quality of the resin determines the durability and cost of the sealer.

Sealer technology is advancing beyond the above model. A couple sealers now on the market utilize cutting-edge chemistry to penetrate deeper and form permanent molecular bonds to the stone. These sealers provide far superior protection and durability, do not break down like resin-based sealers, and do not require re-application once effectively applied.

Topical sealers do exist although their use is questionable in most cases. This type does not allow floor installations to breath, can make the stone look artificial and have maintenance requirements apart from the stone itself.

Myth #3: Let Sealers Dry on Stone

The most crucial step when sealing granite countertops or stone floors is often performed in exactly the wrong manner.

Allowing sufficient absorption time for through coverage is necessary to effectively seal any stone installation.

A critical mistake is made, however, when leaving the sealer to dry on the stone. The usual result is a hazy film covering the surface that typically requires an intensive effort to strip it off.

The same result occurs when applying a sealer to a dense stone that should not have a sealer applied.

The correct procedure after the sealer has saturated the stone is to wipe off all excess sealer and buff the surface dry.

Sealing granite, marble, and natural stone is truly an uncomplicated procedure. Yet myths and misconceptions abound leading to confusion and unnecessary problems for consumers.

As stone industry professionals, we need to be more thorough and precise in our efforts to educate consumers when making recommendations for sealing granite countertops and other natural stone installations to clear up the confusion and better serve our clients.

About the Author

publishes the consumer-resource website providing information, ideas and product advice for marble & granite countertops.