Types of Sealers to Protect your Marble Tiles and Countertops
The natural stone has always been one of the preferred materials for any work, for its beauty, singularity and durability.
However, despite of being one of the most resistant materials in any project, another of its characteristics is its fragility, especially when it is exposed to environmental factors -climatology, humidity, temperature variations, solar radiation, etc-, anthropic factors such as pollution, and of course, the use of it (transit, humidity in kitchens and bathrooms, etc.)
All these factors can generate variations, loss of color, abrasion, spots, scratches, etc. In short, affecting one of its main qualities: The Aesthetic and therefore its beauty.
Since the beginning of the last century, stone experts have been working and researching treatments to improve the performance of it, but also without altering or even improve the aesthetic appearance and behavior of it.
There is a very wide range of surface treatments- “protective treatments, anti-slip, water-repellent, oleophobic,” etc for countertops, tiles, etc.-. But to understand how these types of treatments work, we must take into account the behavior of the stone through three fundamental physical parameters:
- Bulk Density
- Open Porosity
- Water Absorption
The manufacturer must check these parameters with a maximum periodicity of two years for floors and walls, both indoor and outdoor, since they are key parameters in the determination of technical standards and CE marking.
“The maximum periodicity of control of these characteristics
is 2 years”
Like all technical tests, they are made from several samples taken from the quarry.
But what exactly are these parameters and what valuable information do they give us?
1. Bulk Density:
Bulk Density is the relationship between volume and dry weight, including voids and pores. It depends on the density of the minerals and its porosity.
The typical values according to the technical report CEN / TR 17024 are:
- Dense Limestone >2.500 kg/m3
- Other Limestones < 2.500 kg/m3
- Marble 2.600 – 2.900 kg/m3
- Granite 2.400 – 3.000 kg/m3
2. Open Porosity:
The Open Porosity is on the other hand, the volume of pores connected *.
It is a very useful value for determining the type of adhesive or mortar to be used in the installation.
(*) The Total Porosity of a rock includes both the connected and unconnected pores.
3. Water Absorption:
Water Absorption expresses the water that a rock is capable to absorb (%). It is calculated by saturating the sample completely in water.
The value of the Water Absorption allows to evaluate the behavior of the rock against the infiltration of liquids, therefore, the resistance or easiness to get dark spots, the alteration with chemical agents, the penetration capacity of the sealers, etc.
“It is important to take into account the use of the stone walls or pavings in interiors. For wet public areas, spills, splashes etc., as well as in buildings or areas such as kitchens, bathrooms, restaurants, cafeterias, supermarkets, gyms, etc. the value of water absorption should be the lowest possible value”
This should be a general rule, regardless of whether we can apply a treatment that improves or reduces the value of water absorption.
– According to the UNE 22202-01 standard, for cleaning reasons a minimum value of 0.6% is established for interior floors in public spaces with intense traffic.
– According to the American Standard ASTM, these are the specifications of Water Absorption according to type of rock:
- Marble: 0.2%
- Granite: 0.4%
In the case of limestones, given the variability in density of different types of them , the following values are established:
- Dense Limestone> 2,560 kg / m3: 3%
- Medium Density Limestone 1,600-2,560 kg / m3: 7.5%
- Low Density Limestone 760-2,160 kg / m3: 12%
According to these values, the limestones would not be suitable for public wet areas.
- Travertine: 2,5%
The case of travertines is exceptional, due to the high natural porosity of this stone.
The treatments with transparent epoxies resins so frequent in this type of stone, fill the pores (among other factors). This drastically reduces the value of the water absorption so,
“The travertines, in case of having gone through a resin process, could be suitable for wet public areas“.
In conclusion: “the staining of natural stone is a direct consequence of the absorption of water or other elements“. Although, not exclusively, since there are other factors such as the type of finish (the greater the surface roughness, the easier to stain), the size of the pores and the predominant color among others.
These technical specifications are average values that will guide us when making decisions at the time of choosing the materials for our project. But they will not be the only ones, we will take into account aesthetic, functional and ergonomic criteria, as well as sizes and finishes.
As a result of the their natural color, the stones have more or less predisposition for changing the color and staining. For that reason some white marble are more sensitive to moisture than the dark ones.
After understanding how these intrinsic characteristics influence marble and other natural stones, it is easier to realize how they react to the application of Sealants or Coatings.
SEALER TREATMENTS AND COATINGS FOR NATURAL STONE COUNTERTOPS AND TILES
A “Sealer” is basically a liquid that provides the material on which it is applied, with a certain degree of Stain Resistance and Reaction Time. Depending on the type of Sealer, it may or may not change the appearance of natural stone or marble.
There are basically 2 Types of Sealers:
– No Penetrating/Coatings
– Penetrating or impregnations (Pore liners).
1. No Penetrating Sealers (Coatings):
These are superficial treatments that, as their name suggests, “do not penetrate the surface and therefore modify the appearance and final finish of the stone”.
They are designed to protect the surface of the stone from water, oil and other contaminants. They are usually formulated with natural waxes, acrylics and plastics.
This type of sealers are widely used as “non-slip treatments in interiors of public buildings”.
Since they remain on the surface of the stone, they need a maintenance and / or restoration plan, especially in the areas of highest traffic, where stone or marble are subject to greater erosion.
2. Penetrating Sealers (Impregnators):
They are also known as Water based or Solvent based Impregnators.
Its fundamental characteristic is that they penetrate under the surface of the stone through their pores and cover them, but without blocking them, becoming repellents of other pollutants.
One of the main differences with Non-Penetrants, is that by not blocking the pores, they allow the circulation of water vapor and other gases.
This type of Sealers can be Hydrophobic and also Oleophobic.
- Hydrophobic Sealers: repel water and water based contaminants, fruit drinks, coffee, tea, etc.
- Oleophobic Sealers: repel pollutants based on oil, fats, etc.
Note: Oleophobic sealers are also Hydrophobic, but Hydrophobic sealers do not have to be oleophobic. For this reason it is convenient to read the technical specifications of the product.
In addition, this type of sealers, can even get to improve the appearance of the stone or marble, giving it a more natural look, something that with non-penetrating sealers does not happen as they usually provide a more artificial appearance.
Graphic example about the differences between Coatings and Impregnators. Reference: “Study of the behavior of two antigraffiti treatments as protectors of building materials: antigraffiti / substrates interaction, properties and durability”. Paula María Carmona Quiroga ©
Factors to consider when choosing the most suitable Sealer for your Countertops and Tiles
The range of natural stones is very broad, and therefore, the compositional variability of them.
We will need to verify the chemical compatibility between the sealer and material in which we are going to apply it.
Hereafter we can see some examples of compositional variability of ornamental rocks:
- Sedimentary rocks: marble limestones (carbonate composition), sandstones (usually siliceous but also calcareous, feldspathic, etc.)
- Igneous rocks: granites (acidic rocks – high content in silica -), basalts (basic rocks, – low silica content), etc ….
- Metamorphic rocks: marbles (carbonate composition), quartzites (siliceous composition), shales, etc …
Due to the chemical and mineralogical variability of the different types of stone, there are sealers formulated for marble, granite, slates, etc. So we will have to take it into account when selecting them.
Even taking into account the manufacturer’s specifications, it is very important to check how our stone counter or tiles o can react to a sealer (given not only the variety of marbles and other stones, but the variety of brands and properties of some sealers or others).
It is best to carry out a test. Although we can do it in individual pieces, we recommend to do a mockup in the factory or on site (1-2 m2 approximately) and check the behaviour on a surface as representative as possible.
Ideally, in any case, will be to carry out the test for different sealers, so that we can determine which is the most appropriate for our particular material, also depending on the benefits we intend to provide to it. In addition we can make sure of how they respond to different types of substances such as coffee, oil, soft drinks, soda, etc.
Technical issues to take into account when selecting a sealer for marble countertops or tiles.
- If it is based on water or solvent and the degree of resistance to staining that is sought.
- Expectation of life.
- Whether it is for internal or external use.
- Content volatile chemicals that may require the use of masks, ventilation during application, etc.
- Maintenance, how long to reapply.
- If you modify the appearance of the stone.
- Method of application (more or less complex).
The fact that Sealers are formulated in water or solvent base depends on whether the material applied is carbonaceous or siliceous. So we must take into account the composition of our Stone countertops or tiles.
Regarding the level of penetration, it will depend on the porosity of the stone, the molecular size, the amount of sealer applied and the viscosity of the product.
” the most important is to get the necessary penetration with only one application so that the superficial behavior of the natural stone is the desired one”.
Its application is usually very simple, the most common is with a mop or a roller, particularly for water-based sealers. For solvent based may require a certain degree of qualification of the staff, since chemical products are being handled. may contain volatiles.
The effectiveness of the sealer will depend on many factors, and each material will respond in a different way depending on its composition, porosity, water absorption. But also external aspects such as human trafficking, and environmental aspects, etc., can affect the durability of it.
For maintenance, it must be taken into account that there are products specifically designed to clean the stone countertops and tiles and not damage the sealer, so the recommendations of the manufacturer must be taken into account. But, in any case, it will always be appropriate to follow the same recommendations as for the natural stone itself.
To know if you need to reapply the sealant, a good test is the time it takes to darken the stone when wet. As the sealant loses effectiveness, the stone will darken faster.
“The application of a sealer does not mean that we can avoid a stain-proof maintenance, nor that they allow any type of cleaner to be used and, of course, they will not last forever, but ensure a greater durability of our material.”
From the Aesthetic point of view of natural stone countertops and tiles, one of the most important characteristics is their porosity and degree of water absorption.
The value of the Water Absorption allows to evaluate the stone behavior before the infiltration of liquids, therefore, the resistance or ease of staining, the alteration with chemical agents, the penetration capacity of sealants, etc.
The Sealers allow to reduce the porosity to the point of repelling different types of liquids such as water or other contaminants and provide a certain degree of impermeability and resistance to staining, this considerably improves the appearance and durability of the stone over time.
Sealers are classified as Non-Penetrating Sealers (Coatings) and Penetrating Sealers or Impregnators.
Non-Penetrating Sealants are usually more economical but at the same time have a lower effectiveness and durability. They also tend to affect the physical appearance of the stone and even yellowing over time. The best known are those that give an anti-slip effect.
Penetrating Sealers or Impregnators tend to be more expensive but their durability and performance is also greater because they do not stay on the surface of the stone, but penetrate through the pores of it. Therefore, they are not usually affected by UV radiation because they are inside the material. They require less maintenance.
The choice of one or the other will depend both on the benefits we intend to provide to the stone counters and tiles and on the composition of the stone. In any case,
“The best is to provide our supplier with the maximum information about the type of stone que require, the place where it will be installed and the objectives we seek. If we are not very sure, loo for the advise of experts who will be able to compare pros and cons of different options”.
We hope to have clarified some doubts about the wide world of Surface Treatments of the Stone. In álbora we have more than 15 years of experience in carrying out turnkey projects with natural stone, which has allowed us to work with countless types of materials and types of projects.
We are also certified Project Managers (PMP by PMI). We know the natural materials firsthand. We have regulated procedures that help us in the management of any natural stone project, and thanks to our extensive professional experience we know both sectors, Stone and Construction in the international markets.
If you need help, solve your doubts or any other question, do not hesitate to contact us.
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