Current Maintenance: How is the stone maintained? Is it exposed to harsh cleaning chemicals not intended for natural stone? On the other hand, if maintenance is neglected, a stone floor will have ground-in dirt and grit and if it has a high polish it will be worn. In this case, no matter how well it is protected, it will get dirty and dull. For example, a moderately busy hotel lobby floor that gets dust mopped and wet mopped every day may need a good quality impregnator. Which ones are best? Which ones really work? It can be very confusing trying to choose a sealer to protect stone. In the past several years the stone restoration and janitorial industries have bombarded the market with hundreds of products to seal, protect and polish stone. Fortunately, all of these products fall into only two major categories:
Impregnators (Penetrating) Sealers
Coatings are sealers that place a sacrificial coating on top of the stone acting as a barrier to prevent water, oil and dirt from entering the pores of the stone.
Coatings can be classified into two general types:
Strippable coatings are coatings that are designed to be easily stripped or removed from the surface of the stone. These coatings are made of polymers consisting of acrylics, styrene, polyethylene and others. They are usually water based. Many of the janitorial products are water based polymer type coatings. To identify these coatings look for terms on the label such as “metal cross link,” “high solids,” “high speed,” “acrylic,” “thermoplastic,” etc. When in doubt, ask. There are hundreds of different formulas of strippable floor coatings.
Most of them are designed for resilient tile floors and not for stone. If a coating is to be used, be sure it is specified for stone.
Permanent coatings are coatings that are very difficult to remove. They are made of solvent based polymers such as polyurethane, epoxies, etc. These are not recommended for stone.
Many factors need to be considered when choosing the correct sealer.
Stone type: Many, if not most stones today are resigned at the factory. Resining adds strength to more fragile stones thus creating a much larger supply of natural stones that can be used. You can learn more about resining by searching the Knowledge Base at This coefficient is extremely important when choosing a sealer. Granite generally will have a higher absorption coefficient than a polished marble. Limestone can be extremely absorbent. The higher the absorption coefficient, the more difficult it will be to seal the stone adequately.
The finish on a stone affects its absorption coefficient. A polished surface will be less absorbent than a honed or flamed finish. The above absorption test will determine how absorbent a stone is.
Where is the stone located? Is the stone on the floor, wall, and countertop? Is it in a kitchen, foyer, lobby, and bathroom? What are they chances of it being subjected to spills or staining agents? Exposure to water, oil, heavy traffic, pets, etc. all need to be taken into consideration when choosing the proper product for protection. For example, a marble kitchen floor that is used daily will need a sealer that has both oil and water repellant properties. It may track and scuff too easily, requiring costly upkeep. A quality impregnator and a polishing program may be needed to maintain the shine and protection.