Cleaning, Protecting, and Maintaining Natural Stone Surfaces Inside and Around the House: Three Steps for Long-Term Maintenance That Preserves Value

Unlike tiles, which are coated with a stain-resistant glaze or sintered layer, natural stone surfaces are much more sensitive to stains. Even a natural stone like granite, which is extremely resistant to mechanical stress due to its hardness, has microscopic pores that open into the finest capillaries running throughout the material. This makes it, despite its solidity, susceptible to moisture and dirt penetration.

Step 1: Cleaning

Natural stone surfaces are considered colorfast, durable, easy to maintain, and resilient. To preserve their value and ensure the surfaces remain beautiful for a long time, maintenance is necessary that takes into account the specific type of natural stone used and its intended application. With the right knowledge and the right cleaning products, caring for natural stone surfaces is no rocket science. Stone care should be understood as a system consisting of three interrelated steps: cleaning, protecting, and maintaining.

After construction comes cleaning: During post-construction cleaning, all dirt and debris generated during the construction of the building must be removed. This naturally applies to surfaces finished with natural stone as well. If these surfaces were grouted by slurry application or the use of joint mortar, it is almost impossible to avoid leaving residues of the jointing material on the natural stone. These residues cause the surface of the natural stone to become rougher, allowing dirt to adhere even more easily. Furthermore, lime and cement leaching can penetrate the capillaries of natural stone, leading to unsightly and stubborn film formation.

Depending on the type of soiling and the underlying natural stone, different types of cleaners are used. A basic distinction is made between three different types: acidic, alkaline, and solvent-based cleaners.

Acid-Based Cleaners

Mortar residue, cement and lime stains, various types of efflorescence, and discoloration caused by rust can be tackled with acidic cleaners. They are capable of dissolving the aforementioned contaminants, after which they can be rinsed off with little effort. Care should be taken to ensure that the hydrochloric acid content in the cleaner is not too high. If hydrochloric acid penetrates the natural stone, it can cause deep-seated rust formation in iron-containing natural stones—such as certain types of granite that contain ore minerals—which may not become apparent until months later.

An important preparatory step when cleaning natural stone surfaces with acidic products is therefore to pre-wet the surface generously with water. This helps prevent the acid from penetrating too deeply into the surface. After pre-wetting, dilute the cleaning product according to the instructions, apply it with a brush, and let it sit for several minutes. Then, thoroughly rinse the natural stone surface with clean water to remove any remaining cleaner along with the loosened dirt.

Step 2: Protect

Alkaline Cleaners

Surfaces that are sensitive to acid should not be treated with an acidic cleaner. Natural stones such as marble or polished limestone are damaged by acidic cleaners. As a result, the surfaces become dull and unsightly. For such sensitive natural stones, it is recommended to remove dirt mechanically using a white nylon pad in combination with a mildly alkaline cleaner. Here, pay attention to the alkali content in the product; it must not be too highly concentrated. Strongly alkaline products, just like acidic cleaners, can etch the surface of natural stone. Therefore, care should be taken to ensure the cleaner is suitable for natural stone.

Solvent-Based Cleaners

For particularly stubborn stains on natural stone, water-based cleaners may not be sufficient under certain circumstances. If the surfaces are contaminated with adhesives, resins, wax, or similar water-insoluble substances, solvent-based cleaners can be effective. They are applied undiluted to the dry surface—pre-wetting is not necessary and would even be counterproductive because it dilutes the cleaner. Water is used only as the final step: Once the contaminants have been dissolved, they are rinsed off along with the cleaning product using clear water. The mixture of solvent and contaminants forms an emulsion with the water and can then be removed.

If oil and grease stains have penetrated deep into the capillaries of the natural stone, liquid cleaner formulations may prove ineffective. In this case, paste-like oil stain removers are used. They can be left to act for extended periods and are capable of bringing oily and greasy contaminants from deeper layers back to the surface. Oil- and grease-binding additives in these products ensure that the contaminants can then be easily removed.

Once the natural stone surface has been cleaned, the next recommended step is a protective treatment to prevent it from becoming soiled again too quickly. Here, too, there are three distinct methods that can be applied depending on the substrate and the specific requirements at the site. Impregnation treatments reduce the natural stone’s capillary absorbency without compromising its slip resistance. Impregnation treatments do not form a film and, unlike sealants, leave the pores of the natural stone open—thus largely preserving the material’s ability to allow moisture to diffuse. It should be noted that impregnations do not offer protection against mechanical abrasion or chemical influences. Calcareous materials such as marble remain sensitive to acids even after impregnation; their surfaces can become dull as a result.

A distinction is made between invisible and color-enhancing impregnations. While invisible impregnations have no effect on the appearance of the treated natural stone, color-enhancing ones bring out the surface’s color, giving it a wet look. Similar to oiling wood, color-enhancing impregnations can intensify the color of natural stone surfaces and highlight their texture.

The third method is sealing. Unlike impregnation, sealing forms a protective layer on the natural stone that closes its pores and significantly reduces the surface’s absorbency. This reduces susceptibility to staining and makes it easier to maintain the natural stone surface. However, it is important to note that this can also affect slip resistance.

Step 3: Maintenance

Daily use of natural stone surfaces leads to dirt accumulation, which should be removed promptly as part of routine cleaning. Regular damp mopping can remove dirt before it penetrates deeper layers of the natural stone and, over time, forms stains that are difficult to remove. Regular maintenance is essential for the long-term preservation of natural stone surfaces.

When choosing a care product, both the type of stone and the area of use must be taken into account. The wrong product can lead to a buildup of residue on the surface of the natural stone over time. In extreme cases, this can even result in irreparable damage.

During daily or weekly routine cleaning, aggressive or film-forming cleaners should be avoided. Instead, a mild cleaning solution additive is recommended, which is capable of removing general dirt while leaving care components on the surface without forming a film. Products in this category are suitable for all types of surfaces, whether high-gloss polished or rough and slip-resistant.

Additional Care for Polished Surfaces

Even with the best protection, it is impossible to prevent floor coverings made of polished soft stones, such as marble or limestone, from becoming dull over time due to use, and from developing clearly visible wear patterns on their surfaces in areas subject to particularly heavy traffic. Signs of wear like these cannot be chemically removed. In this case, wax- or acrylic-based products can be used. They form a layer on the natural stone surface that conceals the signs of wear. However, this layer also impairs the slip resistance of the natural stone floor, which is why this maintenance option should only be used in private settings.

Non-Slip Surfaces

Due to their rough texture, slip-resistant surfaces are much more susceptible to soiling than, for example, polished surfaces. For routine cleaning, we therefore recommend using a mildly alkaline cleaner. To prevent dirt on rough surfaces from turning into deep-seated stains over time, cleaning should be done almost daily.

Non-slip natural stone surfaces are also particularly susceptible to lime scale that forms during regular routine cleaning. The cause: lime dissolved in the cleaning water settles on the surface, causing the natural stone to appear dull, colorless, and gray over time. If the surface is acid-resistant, removing such a film is straightforward. A strong acidic cleaner, diluted to a ratio of about 1:20, is sufficient to remove the lime film. For indoor use, make sure the cleaning product does not contain any volatile acidic components. For acid-sensitive natural stones, this method of cleaning is not an option. In such cases, the only solution is to carefully wipe down the surface after cleaning.

New: Lithofin Care Set for Natural Stone Flooring 

Just in time for Stone+tec 2022, Lithofin is introducing a new care set: a kit for cleaning and maintaining natural stone and engineered stone flooring, consisting of: 

The mildly alkaline cleaning concentrate Lithofin MN Basic Cleaner quickly and effortlessly dissolves and removes construction and general dirt, yellowed care product residues, self-gloss films, oil and grease stains, light wax films, and stubborn general soiling. 

Lithofin MN Wischpflege cleans and conditions all marble and natural stone surfaces as part of regular maintenance. Special cleaning and conditioning agents ensure surfaces retain a fresh appearance—without the need for wiping. 

Lithofin looks forward to speaking with you in person about natural stone cleaning, care, protective treatments, and networking within the industry. 

Visit Lithofin at Stone+tec 2022 in Nuremberg (Hall 12 | Booth B27) or online at lithofin.de

All images: Lithofin