How to Seal Marble

  • November 26, 2019
  • / By Dale Keese
Cat on Marble Steps

Interior architecture has almost always felt incomplete without the use of marble in the project. The stone has become an unavoidable part of every piece of decor and structure in a house as well as in a commercial establishment. This soft, calcium-based stone is usually cut into tiles which are then used to build flooring and countertops and other structures around a house. It is a strong and durable material which is why builders use it so frequently.

Cat on Marble Steps

However, with all its advantages and aesthetic properties, marble remains a porous material which means that it can absorb moisture and other types of elements from water when it comes in contact with it. When marble is used to build a countertop, especially, it is highly probable for it to come in contact with water which means that it can absorb liquid and get stained. This is why sealing marble is a lot stressed upon.  

Sealing is not only required to stop it from staining but also due to the fact that marble requires a lot of maintenance. It is easily damaged and loses its porousness and also etches, which means that it needs to be regularly maintained and thus sealed to prevent it from deteriorating. If the right marble sealer is used, the marble can be effectively protected against foreign objects that tend to damage it by staining it and getting into the pores.

A sealer essentially acts as a defense against damage to the marble. Therefore, applying a sealer is a critical step in finishing the marble placement since wrong sealers can have the opposite effect and harm the quality of the marble.

We have talked about sealing marble above, but most people are not aware of what a marble sealer is. In simple terms, marble sealer is an element that works as a treatment for marble. It is applied on the surface to solidify the pores of the marble and hence, it prevents any foreign elements from entering the pores and causing damage to the quality and the life of marble. Clogging the pores through a marble sealer ensures that there are no stains on the marble due to impurities it tends to absorb from the water. 

Natural Stone Patterns

Marble sealers are usually liquid-based. The solvent penetrates the pores of the marble and contains a solid resin that ultimately gets left behind to plug in the holes. Essentially, marble sealing is a binding process wherein a sealing solvent is applied on the surface of the stone.

Marble as a stone has pores through which liquids, as well as gases in the environment, can permeate. When a sealer solvent is applied to its surface, it blocks these pores and prevents the environmental impurities to trickle down and clog these pores, thus preventing the marble to lose its natural color, sturdiness and other properties like insulation.

A common myth is that a sealer does damage to the original polish and color of the marble. However, a sealer in no way damages the surface appearance of the marble. In fact, there are impregnating sealers that are applied below the surface and are absorbed by the stone. These do a great job of preventing marble from forming stains. 

Also, a marble sealer cannot be used as a polisher or a shiner since it has no extra shine that it lends to the surface, nor does it protect the original shine of the marble. It does not prevent the stone from its normal wear and tear.

Why is Sealing Necessary?

If it doesn’t help in preventing the common wear and tear of the marble, why is marble sealing a necessary process? Understanding the need for a sealer is extremely important in applying it on the surface of your home or office.

Marble is used in building the flooring and the surface of kitchen countertops, bedroom, living room, bathroom tiles and a lot of other areas. 

Marble can be used in the kitchen, bedroom, bathroom, living room, and even garden. As such, with such widespread use of marble, it is but a requisite to know all possible ways it can get damaged. Here are a few threats to marble that make sealing it necessary.

Home Decor
  • Staining is the most prominent threat to the original quality of the marble. The staining can happen not only in the kitchen but in the flooring of all rooms. The staining is caused by permeation of any kind of liquids or oils in the pores of the marble that result in extreme damage.
  • If you have used marble in any outside structures like columns and walls, there are high chances that it can get damaged due to acid rain. Acid rain results in erosion of the stone and leaves stains on the surface of the marble. The acid, when it seeps into the pores, can damage the entire structure from inside. The structures made from marble can get damaged due to acid that is found in household goods like cleaning solvents, milk, lemon juice and wine. If the liquid contains strong acids, it does not take more than a few seconds to cause permanent damage to the stone while it might be a slower process with weaker acids.
  • Water is another major threat to marble. If water enters the surface of the marble and freezes, it expands below the surface, causing the marble to develop cracks and weather down.
  • When water evaporates from the surface, it leaves minerals behind and causes efflorescence which is the formation of a white sandy deposit on the surface of the marble floor. It causes the marble to lose its shine and polish. 

Types of Marble Sealer

There are different types of marble sealers on the market that can be used depending on the kind of application needed.

Geometric Floor Tiles

Topical Sealers

Topical sealers are the most basic type of sealers that are not that effective. Made from natural wax or acrylics, these are surface sealers and can be used to prevent stains from developing on the stone but are quick to wear out. They also do not provide protection against efflorescence and alter the characteristics of the surface of the marble causing the vapors to stay inside. They do not perform well against liquids.

Penetrating Sealers

Penetrating sealers are good at preventing liquids from causing damage to the marble. Containing siliconates and fluoro-polymers and similar substances, these sealers permeate through the surface of the stone and last much longer than the topical sealers. They also do nothing to the original appearance of the stone and only change the characteristics of the surface to prevent it from damaging.

However, like topical sealers, penetrating sealers, too, are not strong enough to protect the stone against damage caused by efflorescence.

Impregnating Sealers

Impregnating sealers are the most advanced marble sealers that contain modified silanes. They have the strength to percolate deep inside the surface of the marble and bind the pores with its molecules which ultimately prevents liquids like water and oils from seeping into the surface.

They are also effective against frost weathering and efflorescence since they are able to penetrate deep into the canals and fill the holes quite well. These are primarily before the surface sealers and hence are able to do a much better job of preventing damage to the marble from the external environment. The extreme penetration is effective in preventing damage against erosion and UV light as well.

Marble sealers are used after the application of a special type of cleaner that clears the surface of all residual harmful elements that have collected on the stone. Once it is cleaned, then the sealers are used for maximum effect.

How Do Marble Sealers Work?

A marble sealer is designed to prevent liquids to penetrate the pores of a marble top or flooring so that there are no stains. For instance, if you spill water or coffee or any other liquid on a marble countertop and don’t clean it immediately properly, it has the ability over time to seep into the surface and once it does, it evaporates to leave a trail of stains behind it. 

Vintage Bathroom Sink

A sealer contains a solvent carrier that is designed to penetrate into the pores and settle down the solid resins the solvent contains. The resins, in turn, clog the open pores and prevent the foreign impurities from percolating into the surface and forming stains. These are impregnating sealers that work from below the surface once the marble surface has been cleaner using special cleaners.

An important point to remember here is that even though marble sealers are considered to be the utmost way of preventing marble from getting damaged, they are ultimately an external solvent and the marble still needs to be looked after regularly to maintain its polish and shine. For instance, even though you might have used a marble sealer to prevent stains, it is always a good idea to use a cleaner immediately whenever there is a spill. 

The sealer is physically absorbed by the stone and then only it can do its job. However, there are stones that do not absorb the sealer and let the liquids seep into the surface. The absorption rate of some marble stones is less than 0.2% which means that it also cannot absorb liquids. In such cases, there is no use of applying a sealer on the surface and it might end up harming the marble more than it might benefit it.

A sealer that is not absorbed ultimately reacts like any other liquid and leaves behind stains once it’s evaporated, unless it is absolutely wiped from the surface. Moreover, since the sealer contains solid resins, they also get left behind that create a gritty surface and spoil the original shine of the marble.

How to Seal Marble

A marble sealer, if not used properly, can do more harm than good to the surface of the marble. There are specific steps one needs to follow to effectively seal marble. Let’s take a look at the steps on how to seal marble.

Tea Time

Cleaning the Surface

Before applying a marble sealer, the first step is to clean the surface of the marble with a soap water solution. While any normal soap that’s used to wash utensils might also work fine, it is always better to use solvents that are designed specifically for stone surfaces for most effective results, especially if the surface is a kitchen countertop that has been weathered by exposure to cooking oils and other kinds of liquids that accumulate grease.

A marble cleaner removes this grease and cleans the surface thoroughly. Once the surface has been washed, it needs to be rinsed again with clean water and then left to dry completely. This will ensure that all impurities that might interfere with the properties of the sealer are completely removed from the surface.

A point to note here in case there is a specific surface that you intend to apply the marble sealer ensures that all other areas are properly taped off. For instance, chrome and steel surfaces that are around the marble surface needs to be covered before applying the cleaner and the sealer to avoid causing any damage to them. For this purpose, a high-quality taping paint can be used.

Apply the Sealer

For convenience, pour the sealer solvent into a container with a large mouth so that you can easily dip the paintbrush into it for application. To make sure that the smell of the sealer does not cause any harm to the user, keep the ventilation open and allow the VOCs in the sealer to escape the room. 

Once this is done, dip the paintbrush in the container and spray the sealer on the counter or any other marble surface with repeated 2-3 strokes that overlap each other. Ensure that all areas that are under the marble surface are covered by the sealer, including the edges and areas around the sink if it’s a countertop.

Do not disturb the coat once applied and let it dry for at least 15 minutes up to half an hour. Leaving the sealer on the surface for this long allows the liquid to seep into the surface of the stone and effective spread into the pores to plug them in against any harmful liquids. 

Before applying the sealer to the entire surface, it is a good practice to apply the sealer on a smaller area and test whether the sealer is compatible with the stone and does not harm the surface by discoloring it. Once the sealer dries in the test area, compare the color to the larger area and check the difference. If the color difference is too huge, then the sealer is not very compatible with the stone, since the only difference should be in terms of glossiness of the surfaces.

Add Another Coat

If you are looking for extra durability, you can add another coat of sealer on the surface once the original strokes have dried. This is especially important if it’s an overused marble surface like a kitchen countertop. Once the first coat has dried, apply a second coat in the same fashion and let it remain on the surface for another half an  hour. 

Some sealers come with instructions and ask for use of a foam brush to apply it. Therefore, ensure that you read the instructions carefully before using the sealer.

Wipe the Surface

Once both coats have dried off, wipe the surface with a clean and dry soft towel or cleaning cloth. Keep cleaning the excess sealer with the clean cloth in a circular motion until the surface is absolutely dry and does not feel sticky on touching it. Excess sealer, if left behind, spoils the finishing of the surface, therefore, it is important to clean it. 

The marble surface after applying the sealer can be used after about eight hours. The duration before which the top can be used again depends on the environmental conditions like humidity and temperature. Generally, it might take a day for the surface to become completely usable again. While it is fine to use for light purposes, full use of the surface will resume only after that.

Swimming Pool

Factors Influencing Absorption of Sealer

Not all stones are the same. Each marble stone can be different in terms of color, porosity, and hardness. While some stones instantly absorb liquids, others take a long time for liquids to seep into them before they soak them. Therefore, it is implied all stones will react differently to marble sealers and also to different types of sealers. 

Another factor that influences the absorption of the sealer in the stone is the surface finish of the marble. A polished marble finish tends to have a lesser absorption capacity than the surfaces that are naturally left unfinished. This is because when the marble surface is polished, a lot of pores are removed and hence, the porosity of the stone is significantly reduced. This, of course, means that polished marble stones also absorb other liquids lesser. 

Similarly, honed marble surfaces also absorb lesser than the naturally unfinished stones due to the same reason as the polished surface. Honing the marble surface reduces the pores and thus reduces the absorption capacity of the marble. Like polished marble, therefore, honed marble also absorbs other liquids lesser and is less prone to damage. 

These differences in the basic characteristics of the marble surfaces decide whether the marble sealer will work on the stone or not. To determine whether it will absorb the sealer, there are ways to test the properties of the marble. You can run the water test on the surface and decipher if the stone will benefit from the sealer or not. This is also useful in cases where you are not sure how much time has passed since the surface was sealed the last time.

To conduct the water test, you need to pour water on different areas of the surface. The area covered by water in different spots can be about 3 inches in diameter. Leave the water on the spots for about half an hour.

If the spots start to get dark and stain, it is time to seal the surface again. So, if the water seeps in the marble and stains begin to form, the surface needs staining. On the other hand, if the water does not penetrate and begins to pool on the spots, there is no need of applying marble sealer.

The Probability of Staining

Even though a marble surface absorbs liquids, it does not necessarily imply that you need a sealer to bind the pores. What matters, instead, is whether the liquids absorbed will leave a stain behind and damage the marble surface. This is more probably for surfaces that are frequently in contact with damaging liquids like cooking oils and dishwashing liquids, etc., that contain acids and other elements that can cause severe harm to the surface of the stone.

On the other hand, when we talk about shower marble, it barely comes in contact with such liquids and others that might cause stains. It only comes in contact with water which is instantly cleaned too. Well, that also depends on the quality of water that you are getting in the shower. But generally, a shower marble rarely requires the use of a marble sealer. 

On the other hand, something as overused as a kitchen countertop will definitely require sealing since it regularly faces the damage caused by liquids used in the kitchen that holds immense power to stain it. If it is absorbing these liquids, using a marble sealer will prove to be a lifesaver with respect to its durability and overall strength. 

Therefore, while it may be considered as implicit that a marble stone will absorb liquids, it is better to check first and then apply a sealer since applying a sealer on a surface that doesn’t need it will only harm it further.

Modern Minimalist Kitchen

Maintaining a Marble Surface

No matter where you are installing marble, be it your house or an office, and irrespective of whether you are the one who is installing it or it was already there when you moved in, maintaining a marble surface is imperative if you want it to last for long, which means that it is necessary that marble sealer will be frequently applied.

Not maintaining the marble stone results in severe consequences. On the slightest neglect, over time, irreversible damage can be caused to the stone in the form of stains. These stains, if not taken care of immediately, etch hard into the surface and become impossible to remove. This will ultimately lead to calling a repair professional and refinishing the marble surface all over again, which is a costly affair. 

All of this can be prevented by following a simple maintenance routine.

Regular Cleaning of Counters

The counters and other marble surfaces should be regularly cleaned by a dry clean cloth to wash off any impurities resting on the surface. For this purpose, while it is alright to use normal dishwashing liquids, it is more beneficial to use specially designed marble cleaners that contain solvents that remove hard stains from the surface.

Regular household cleaners can cause more damage over time and cause the surface to lose its luster. Oil stains on a countertop can be removed by applying a mixture of baking soda and acetone, and cleaning it with the paste. Similarly, hard coffee stains can be cleaned by using bleach and water and dried with a soft towel.

Regular Use of Sealer

Using a marble sealer after cleaning the surface is important the first time the surface is installed. However, it is also important to keep resealing the marble surface over time. The stone loses its sealing properties over time due to common wear and tear and overuse. There are ways to test whether the surface needs to be sealed again.

If you don’t want your marble surface to decay, keep checking at regular intervals whether the surface is in need of reapplication of a sealer. You can run the water test frequently and check this. It is important to note you can not overseal a marble stone, therefore, even if you seal it frequently, there is no harm that will come to the surface. 

Running in the Hallway

Final Thoughts

Sealing marble is important if you want to maintain its color, porosity, strength, durability and increase the life cycle of the stone. Not maintaining it properly only proves to be more expensive since any damage will need to be fixed by a professional who will most likely refinish the stone and that’s an expensive affair. There are different types of stones and hence there are different types of sealers that can be used.

As important it is to maintain a marble surface, it is equally important to know whether the marble stone you have installed needs sealing or not. Some stones, mainly the ones with natural finishing, do not need sealing since they do not absorb liquids.

Either way, you can increase the shelf life of the beautiful marble interiors of your house with a little care and vigilance. Before deciding on a marble sealer, do a thorough check of the stone and follow the steps properly.