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Does All Natural Stone Need to Be Sealed?

It's a question that you cannot avoid running onto when researching care and maintenance for stone surfaces. And it seems like the answer is complicated and difficult to answer succinctly. The reason it is so challenging to answer the question, "does all natural stone need to be sealed?" is that you hear many authoritative answers that seem to disagree on the subject. In this article, we will work to clarify the answer to this question. And although our explanation won't be succinct, we will endeavor to present the answer in a clear and understandable way.

Defining "Natural Stone"

Depending on whom you ask, you will receive a variety of definitions as to what "natural stone" actually is. Why is that the case? Well, it turns out that there are man made materials that some refer to as stone that others do not. This happens because some or all of the ingredients used are minerals that are found in natural stone. So for some, they view it this way, "if the material is made up of components found in natural stone, then it must be stone too." It is also helpful to differentiate between "stone" and "natural stone".

For the purpose of this article and our discussion, we speak of natural stone in the sense that the material formed through natural processes without man's involvement. That is not to say that the material was not worked on by humans. Rather, it means that man did not make the material. Most natural stone gets cut, shaped, and polished before it makes its way into a project. But all that happens after the material forms naturally.

Natural Stone and Sealer

Now that we have established what we mean by the term natural stone, we can begin looking at the core topic under discussion. Namely, "does all natural stone need to be sealed?" Let's start by considering why there is a need for some natural stone to be sealed.

Why Natural Stone Needs Sealed

Natural stone is porous to one degree or another. Depending on the kind of stone and even the grade of the stone, the porosity will vary. For example, some types of stone are less porous than other types. Slate for instance, is less porous than travertine, as a general rule.

Just because two slabs of stone are the same type, it does not mean that they have the same porosity. Why? Because stone comes in grades. These grades are defined by characteristics the stone possesses. One of these is porosity. The porosity of the stone is what makes the material susceptible to staining. Oil based and water based substances can be absorbed into the pores of a natural stone material and discolor the material in that spot. The answer to this is to seal the stone using a sealer for natural stone materials. So far, it sounds like the answer to our question is yes, all natural stone needs to be sealed. But wait, let's look a little closer at the details.

Cases for Consideration

The problem with simply claiming that all natural stone must be sealed is that it overlooks specifics. For example, does a granite countertop need to be sealed if it was just sealed two weeks prior? What about a month? You get the idea. Now it might seem as though the answer to those questions are obvious. Many would say that the answer is no! They may reason that a sealer application should last longer than a month. But remember, using the wrong kind of cleaner on natural stone will (not might) destroy sealer from previous treatments. That's why it is imperative that a cleaner specifically designed for natural stone be used to clean natural stone.

Another reason it cannot be said that all natural stone needs to be sealed is because of cases like natural soapstone. Following that link, you will find an article we wrote that talks about natural soapstone and its properties. In that article we said the following:

The first property that we will mention regarding soapstone is its porosity, or rather its lack thereof. Soapstone is one of the few non-porous natural stone materials available for countertops.

Since soapstone is non-porous, it does not need to be sealed. So there is another specific case where the statement "all natural stone needs to be sealed." is not true.

Testing Whether Sealer Is Needed

Since there are cases where sealer application is not necessary and there are other cases where sealer does need to be used, how can you tell when stone needs sealed? Well, the answer to that question is, test the stone. By testing whether a stone needs to be sealed, you can determine if a particular surface currently needs sealed.

How to Test Absorbancy

Testing if a natural stone surface is in need of sealer is done using a simple three step procedure. The procedure is as follows:

  1. Pour distilled water on the stone's surface.
  2. Wait for a period of time.
  3. Observe the rate at which the stone absorbs the water.

This simple test reveals one thing to the observer. Namely, how fast the stone will absorb liquid. The first step mentions using "distilled" water because water that contains minerals can actually discolor the material in certain cases by carrying minerals into the pores of the stone. Once the water leaves the area of the stone the minerals stay behind.

The rate at which the natural stone receives the water indicates how long the consumer has to clean up any spills that occur. By applying stone sealer to the surface, the clean up time is increased.

As we have seen in this article, each natural stone surface is a unique material. Furthermore, from day to day the absorption rate of a given stone changes depending on the amount of sealer it has retained up to that point, what kind of stone it is, and what other treatments have been applied. So the technical answer to the question, "Does all natural stone need to be sealed?" is no. But for practical purposes, the answer is yes, virtually all natural stone needs to be sealed at one point or another.

Knowing a little bit about natural stone, what is meant by the term, and understanding a little bit about what sealer is and what it does goes a long way to getting the results you are after.