WONASA Natural Stone Maintenance Guide (Professional users)

Guide 1- For the Professional Users



Natural stone is beautiful, representative, and thanks to modern techniques of quarrying, manufacturing, and processing, affordable for almost anyone. Each slab is a piece of nature and, therefore, unique.


Natural stone remains, ‘naturally,’ unchanged over centuries; it is not subject to the constant fluctuations of market currents, to what is ‘hip’ and ‘fashionable,’ as is the case with artificial/synthetic materials. Furthermore, natural stone provides the designer with many a possibility of usage and application. Flooring and paneling can be treated with a number of surface applications: depending on the surface treatment, the stone appears lighter or darker, its colors can be more or less intense, it can feel smoother or rougher. Natural stone can be manufactured in massively diverse ways. As such, flooring and paneling, processed, to offer just one example, with ceramic tiles, can be complemented with as many other items as massive shower trays, washbasin, shells and panels, basin and pool bordures, monolithic bathtubs, and even sculptures.


There is a plethora of different stones with a wide variety of colors and textures, each one with its own properties and characteristics. This individual variety comes with its own structural-physical properties.


Now, this rich variety can be both a blessing and a curse. It can be the reason for wrong choices and improper treatment regarding cleaning, protection, and care. These mistakes in treatment cause problems which can often, unfortunately and unjustifiably, bring natural stones into discredit. Even misnomers, such as referring to all hard stones as “granite,” have led to an unjust discrediting. Not all hard stones are “granites,” and very often what is referred to as “granite” is not a genuine granite in the stricter sense.


This guide provides the consumer with an “easy-to-read” manual in the form of questions and answers and helps him or her to master the daily challenges of preserving the original quality of natural stones in order to enjoy for the longest possible time this precious and valuable material.






Q1. What is the difference between granite, marble,limestone, sandstone, slate ?

The difference between miscellaneous types of natural stone starts right with the origin of its creation:

Granite is an igneous rock with at least 20% quartz and up to 65% alkali feldspar by volume. Marble is a non-foliated metamorphic rock composed of recrystallized carbonate minerals, mostly common calcite or dolomite. Marble, in other words, is a metamorphosed limestone. Limestone is a non-foliated metamorphic rock (sedimentary rock) composed, mainly of skeletal fragments of marine organisms such as coral, forams and mollusks. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Sandstone is a sedimentary rock composed mostly of sand sized minerals or rock grains. Slate is a finely grained, foliated homogeneous metamorphic rock, derived from the original shale-type sedimentary rock, composed of clay or volcanic ash, by means of low grade regional metamorphism.

Each of these different varieties has their own properties and appearance, and requires therefore an individual approach and differing applications.


Q2. What is hard and soft stone?

Generally, stones are categorized into hard and soft stones. “Hard stones” include granite, gabbro, syenite, and diabase. The materials subsumed under this category are wear-resistant and in most cases suitable for all forms of installation. Commercially, these stones are mistakenly referred to as “granite”. Equally classified as “hard stones” are porous vulcanite and slate stones. These, too, are suitable for any kind of installation. “Soft stones” range from so-called sedimentary rock such as limestone and argillaceous shale to metamorphic rocks such as marble. In most cases suitable for flooring, these stones are mostly used for paneling and less demanded areas. Commercially, these stones are commonly referred to as “marble” or “limestone.” Sandstones, too, offer a variety of possible applications if used as soft stones, preferably as flooring material.


Q3. What is the stability of the natural stones against acidic chemicals?

Is the natural stone acid-sensitive (limestone, marble, many sand stones, argillaceous stone), then those chemicals are not to be used:

Generally, soft stone (such as limestone, marble, many sand stones, argillaceous stone) are acid-sensitive and are therefore not to be treated with acidic chemicals. Hard stones (such as granite), on the other hand, are acid-proof. However, the general classification of “granite” includes some gabbro and basalts which are not acid-proof, such as, the Indian star galaxy or the South-African Nero Absoluto and Impala, as well as different kinds of diorites such as the Brazilian stone Tijuca. These “relatives”of granite consist of a wholly different chemical composition and can therefore not be classified as granites.

Additionally, what is commonly referred to as “black granites” include natural stones which are not granites at all and which, therefore, are also not acid-proof.


Q4. How to choose the right natural stone for a project?

Besides the appearance, colors and design of the natural stone the most important criteria for choosing the appropriate climate for indoor and outdoor applications are: frost resistance, abrasiveness, water absorption, acid resistance, suitability for flooring and cladding, polishing possibility.





(In the factory or outside factory stage)


Q5. Why is it necessary to pre-protect the stones before application?

The main concern before application is begun is how to protect the stone against attacks. Protection concerns all six sides (surfaces) of the stone.


Q6. How to pre-protect the Natural Stone for indoor application?

Flooring and Walls (Façade dry-cladding): The best way to prevent blooming and stains caused by moisture and to avoid or reduce rust stains is to impregnate all six sides (surfaces) with a suitable solvent- or water-based Stone Protector.

Walls (Façade wet-cladding): In case of wet-cladding it is recommended to seal the back-side of the natural stone with a thin coating layer of a 2-component resin system with quartz sand dispersed on it. The quartz sand layer acts as an adhesion primer to the laying cement mortar. Treat the remaining 5 sides with a suitable solvent- or water-based Stone Protector.


Q7. How to pre-protect the Natural Stone for out-door application?

Flooring and Walls: (Façade wet-cladding): In both cases it is recommended to seal the back-side of the natural stone with a thin coating layer of a 2-component resin system with quartz sand dispersed on it. The quartz sand layer acts as an adhesion primer to the laying cement mortar. Treat the remaining 5 sides with a suitable solvent- or water-based Stone Protector.


Q8. How to pre-protect the Natural Stones (marble as well as granite) by laying a floor or to install by wet-cladding, if the back-side is already treated (protected) with net and resin, which could not adhere, using a cement mortar?

In both cases it is recommended to treat the back-side of the natural stone with a thin coating layer of a 2-component resin system with quartz sand dispersed on it. The quartz sand layer acts as an adhesion primer to the laying cement mortar. The other 5 sides we treat with a suitable solvent- or water-based Stone Protector.

Walls (Façade dry-cladding): The best way to prevent stains caused by moisture is to impregnate all the six sides with a suitable solvent- or water-based Stone Protector.






After the end of installation two important procedures follow: the initial post-installation cleaning and the basic protection.

3.1.Initial Post-Installation Cleaning


Q9. With what forms of staining and dirt are we dealing with?

1. Cleaning blown-up coarse dirt (e.g. sand) and fine dirt (e.g. coarse dust).

2. Cleaning adhering dirt, either water-soluble (e.g. soil or fine dust) or not water-soluble (e.g. residues of mortar, cement, or joint fillings, putty, adhesive labels, marker-lines)

3. Cleaning special stains (e.g. residues of epoxy resin or stains caused by packaging material that had been placed onto the surface).


Q10. How can coarse dirt be removed?

Coarse dirt can only be removed mechanically by using an upright vacuum cleaner or vacuum sweeper. Do not use a broom, since that would blow up quartziferrous dusts which are highly damaging to one’s health. Avoiding any production or proliferation of dust is paramount.


Q11. How can I remove the adhering dirt (water-solvent)?

Water-solvent dirt is removed by damp- or wet-wiping. With vacuum scrubbing a mechanical support is being provided (scrubbing) that helps unstick and detach of adhering dirt while suctioning the dirty water. Same goes for wet scrubbing with brush or pad and subsequent wet suctioning.


Q13. How can I remove the adhering dirt and stains (not water-soluble)?

Dirt and stains that cannot be removed with water are differentiated based on their solubility:

- Dirt and stains that can be removed with acidic cleaning products, e.g. cement residue, mortar residue

- Dirt and stains that can be removed with alkaline cleaning products, e.g. waxes, fats, general soiling’s.

- Dirt and stains that can be removed with solvent cleaning products, e.g. oils, adhesive tapes.


Q14. How can cement residues be removed without damaging the stone surface?

Considerable maltreatments can happen with the cement residue removal. Cement residue are rests of cement join fillings sticking to the floor surface. These can only be removed by using acidic solvents. Cement residue removers are, consequently, acidic products, which dissolve residues of cement and lime. The composition of the products (kind and concentration of the acid) can vary considerably. Every kind of acid has its pitfalls and not all of them are universally applicable to all natural work stones. Depending on surface treatment and intensity of pollution, mechanical assistance should be added to every application of cement residue remover.

If the stone is not acid-resistant, a mechanical removal with an alkaline solvent can be attempted; however, the cleaning product will not immediately and entirely remove dirt from the surface.

In the acid-sensitive natural stone with a rough surface, removing cement residues presents a different situation. Often one is faced with the question of whether to grind over or rework the natural stone to the entire floor material. In this case, it is possible to use a highly-diluted cement residue remover after having pre-wetted the surface in order to acidify the surface, if the resulting roughening of the stone remains unperceivable on its rough surface and the damage remains within acceptable terms.


Q15. Why do I have to pre-wet the acid-sensitive natural stone before applying acidic chemicals?

The easiest way to protect both the natural stone and the joints from acid is to pre-wet the floor. The rule is simple: if water has got in, then acid cannot get in. The cement residues then lie on the surface and can be dissolved by the acidic influence. Most cement residue removers dissolve the cement, but do not clean its surface. For the sake of neutralization, the flooring must be cleaned with an alkaline basic cleaner. It is advisable to always test the product on an inconspicuous area, since it is never completely clear what the exact reaction is going to be between stone and product.


Q16. What happens with the joints during the cleaning process?

The joints are very acid-sensitive, even those made of synthetic material. As a general rule, there should be a ten-days waiting period between the jointing and the cement residue removal. Additionally, pay attention to the guidelines of the grout manufacturer.


3.2. Post-Installation Protection (Basic Protection)


Q17. Is a final protection necessary?

Yes. The pre-protected surface of natural stone after the intensive cleaning with more-or-less strong chemicals and in addition to the mechanical strain during the cleaning is not enough for a long-lasting protection. In case the natural stone after laying will be reground and re-polished (mainly for soft stones),a basic protection is compulsory.


Q18. How many kinds of protection do we have at our disposal?

For the care and protection of natural work stones two basic groups of processes and products are available:

-Impregnation (not layer-forming products) and

-Sealing (layer-forming products)


Impregnations are classified as water-repellent (hydrophobic) and water- and oil-repellent (hydro- and oleophobic). The applied impregnation product penetrates into the surface pores of the stone and is taken up by the poricidal walls. A capillary transmission of fluids into the stone is made impossible. Impregnation products do not entirely close up the pores of the natural stone, however, transmission of water is only possible in the form of vapor, no longer in liquid form (water vapor diffusion). Depending on the product, the rate of water vapor diffusion may equally decline.


Q19. What is the difference between sealing and impregnation?

Unfortunately, in the English language, we use for both kinds of protection, the word “sealer”, “sealing”. The word “sealing” in case of impregnation is misleading. It implies that the stone is so entirely covered that it is unable to breathe, which is not the basic property of the impregnation.

Sealing can be achieved; however, it depends on the kind of stone. For example, we could do sealing on “sheet stone” like slate, or where the back-side of natural stone is open to ventilation (e.g. ventilated façade).

Impregnations are not layer-forming, but penetrate into the stone structure and cause a visible reaction on the poricidal surface. They emulate the natural vapor diffusion rate of the stone.

Therefore, they do not provide a complete protection against stains, they solely prevent stain-producing substances from entering too easily into the stone. Impregnations do not provide protection against acids, such as those found in fruit juices.

Sealings, on the other hand, are layer-forming products. They should not be applied to backstage moistened coverings since they prevent a diffusion of humidity and can therefore cause discolorations and whitening underneath the covering. Sealings should not be used on or around kitchen countertops, since they are not particularly heat-resistant or scratch-proof. To avoid unnecessary trouble or reclamations, the costumer or client should be thoroughly briefed beforehand.


Q20. Who should perform the impregnation?

In general, a stone expert, e.g. a stonemason, who is familiar with the impregnation of flooring and other surfaces made of natural stone. The person should, however, prove conversant with the application of adequate products as well.


Q21. Can impregnation protect the stone from acidic influences?

Impregnations provide primary protection, i.e. the absorption of stain-forming substances is being delayed and reduced by impregnation. Impregnation does not protect against acidic influences. It is important to remember that drinks such as fruit juices, sparkling water, fizzy drinks etc. are considerably acidic and can attack acid-sensitive stones. Stains caused by acidic influence are therefore immediately to be removed.


Q22. How many different types of impregnation products are there?

Depending on the respective solvent and effects, impregnations are categorized into:

- water-repellent (hydrophobic), water-based, without color-enhancing

- water-repellent (hydrophobic), solvent-based, with and without color-enhancing

- water- and oil-repellent (hydrophobic and oleophobic), water-based without color-enhancing

- water- and oil-repellent (hydrophobic and oleophobic), solvent-based with and without color-enhancing

It is important to note that even with impregnation products which are not color-enhancing, a deepening of color, albeit a slight one, can occur the color depending on the stone. Therefore, a test-application on a sample area should be conducted before the actual procedure. If need be, obtain previously an official approval from the client. In certain cases, a more or less intensive deepening of color might be in the client’s interest.

Solvent-based impregnations give the impression of a more intense color. Thanks to their superior penetrating properties, these products achieve a better effect on stones with diminished absorption.


Q23. What does one have to take care of before beginning with the impregnation?

A dry and cleaned stone surface is especially important for a successful impregnation. Before any impregnation, the surface must be dried and cleaned. All stains must have been removed and the surface should be absorbing. A thorough cleaning is the essential pre-condition for a later successful protective treatment. Stains that have not been properly removed before treatment are a lot more noticeable and much harder to remove post-impregnation.


Q24. How can one decide on a water-based or solvent-based product?

Dry stones have higher absorption capabilities and are therefore better suited for solvent-based impregnation, which provide a superior protection compared to water-based impregnations. However, solvent-based impregnation cannot penetrate a wet stone and then sink into its capillary structure. Should the stone be considerably moist or not properly dried, the following problems can occur during a solvent-based impregnation:

1. film formation on the stone surface

2. proper drying is hindered due to temporary clogging of the capillary (possible spotting due to internally harboured salts)

3. Adverse reaction of the agent with the prevailing moisture (permanent discoloration)

4. Insufficient protection effect can cause marginal damages.

Water-based impregnation is suitable for natural stones which are difficult to dry well. Water-based impregnation has decreased penetration properties on less-absorbing stones. It therefore achieves a less than ideal protective effect, but also does have less “damage potential.” If applied, the following problems can occur:

1. Insufficient protective effect

2. Film formation on the stone surface


Q25. What causes problems during and after impregnation?

When it comes to impregnation, the following conditions can cause problems:

1. Too much remaining moisture after laying and cleaning, respectively.

2. Overapplication: surplus on the stone surface (film formation)

3. Underapplication: too sparingly applied product leads to insufficient protection

4. Stone warming (sunlight exposure, underfloor heating) causes film formation due to the solvent evaporating too rapidly.

5. Insufficient pre-cleaning (rests of cement residue, other forms of pollution and residue of previously applied care products)

6. Exposure to humidity immediately following impregnation (especially in outdoor areas, e.g. rain)


Q26. What is the behavior of “dark stones” to impregnation?

Several dark stones can alter their color after an impregnation treatment. In many cases, this is a desired effect. There are many natural stones, however, which react differently to impregnation solutions and end up covered in stains and spots. This often happens in rough materials such as quartzites and gneiss. Other stones, such as the Norwegian otta phyllit, can lose their so-called 3D-effect, a three-dimensionally looking shimmering on the surface, after an impregnating treatment. The impregnation of such sensitive kinds of natural stone specially require an impregnation with Nano-effect. These products are applied onto the clean and dry surface. After an application time of 5-10 min. the residues are being removed. The full impregnating effect sets in just after 2 hours. The product does not cause any color deepening.


Q27. How can I determine the dryness of the stone surface?

There is a simple test to determine whether the stone surface is sufficiently dry. Lay a foil or newspaper over the surface. A “sweaty” foil or a “wrinkly” newspaper point towards a prevalent humidity. This test might be imprecise, but can be easily executed.

It is important to stick to the necessary waiting time between cleaning and application. Often, a floor surfacing seems to be completely dry within an hour after cleaning. This appearance may be deceiving. Far from being dry, the stone may be completely soaked inside its capillaries. The duration of the drying time depends, among other things, on the absorbing capacities of the stone and climatic conditions such as temperature and humidity as well as existing ventilation.


Q28. Which tools are used to apply stone impregnation?

To impregnate a stone, the product should be applied fully and evenly with a paintbrush, seal brush, flat dust mop, and short paint roller in a cross stitch pattern. Impregnations can be sprayed too, e.g. on vertical areas. Liquid impregnations are best sprayed onto the surface, since this technique facilitates a more even application than using a roller. During application, it is important to avoid leaving behind puddles. Surplus material must be removed with cloth or paper before drying up.


Q29. Is possible to repeat the impregnation?

Re-impregnations are unproblematic with liquid products, but can cause problems with solvent-based products. It is therefore advisable to apply sufficient impregnations and to facilitate an immediate and complete absorption, since a surplus of impregnation will cause a film formation on the surface which will then have to be removed. A film on a stone surface impregnated with solvent-based products will cause uneven abrasion under mechanical exposure (e.g. footprints). Such films can easily be removed up to one week after impregnation with a basic cleaner or an impregnation remover. Nowadays, many natural stones with polished surfaces have been pre-treated as early as in the factory (resination) stage. As a result, the stone’s absorption properties are highly diminished. Surfaces of these stones can change considerably when treated with solvent-based products.


Q30. What is the Life-time of impregnations?

Regarding liquid and solvent-containing impregnations, the life-time of the treatment depends strongly on cleaning and care of the impregnated areas. If cleaned with alkaline substances, water- and oil-repellant impregnations are much durable than impregnations that are only water-repellant. Kitchen countertops should be re-impregnated once a year, surface coatings in bathrooms or swimming areas once every three years (showers and washstands once a year). For coatings in regularly utilized areas which are carefully maintained re-impregnation should be considered every 5 to 10 years.



3.3. Maintenance of Natural Stone



Q31. Which are the well-established cleaning methods?


The old-fashioned broom is still a valuable part of everyday maintenance of any floor surface – natural stone included. It is very important to remove soils from flooring surfaces. Soils are abrasive. The more often soils are removed, the longer the floor will retain the original appearance. Use a broom with a bristle that matches your surface. A soft broom or brush is recommended for smooth surfaces like marble, sandstone and limestone. A medium to soft bristle is ideal for textured surface.


A good vacuum cleaner works better and more efficiently on textured surface than a broom. Use a vacuum on any horizontal surface when large areas are involved, since it is, in most cases, faster than sweeping.

Damp Moping:

A damp mop is capable of picking up microscopic abrasive soils and potential staining agents. Damp mopping is recommended for most smooth surfaces on a regular basis. Best done after sweeping or vacuuming.


It is essential to clean a floor regularly. The working conditions will dictate its frequency. The most widespread problems encountered with stone floors are related to the floor simply not being regularly cleaned.


Rinsing is one of the most critical steps in regular floor maintenance. Dirty mop water residue is common and a cause for much complaint. A two bucket rinse method is highly effective in keeping floors from graying out due to soil residues.

Abrasive (mechanical cleaning:

Abrasives are sometimes useful as a cleaning agent but should be limited to non – polished surfaces. Abrasives may be combined with detergents or soaps for scouring a surface and removing thin layers from the surface. There are many different types of materials used as abrasives – soft abrasives may be composed of nutshells or feldspars, hard abrasives can be silica quartz, carbide or even diamond.


Q32. What can ruin or cause damage to a stone?


Spills from drinking liquids or food containing acid will etch (dull mark) marble and limestone surface. Also the wrong declaration of some group of natural stones can cause irreparable damages. The so called “black granites” which are partially basalt such as Tiger Black or Chinese G684 or Gabbro as Star Galaxy, Nero Absolute, Impala or in the case of Belgian granite, which is limestone, all of them are sensitive against acid. In such cases, lemon juice, orange juice, carbonated beverages, cranberry juice, apple juice, wine, tomato, etc. may cause a dull mark that may be of a coin size or spread over the surface.


In addition to chemicals containing acid, chemicals that contain high alkaline or bleach can damage floors to lose its shine and elegance.


Local water may contain chlorine, salts, magnesium, potassium and other minerals. When water is used continuously to clean the marble and limestone floor it may ruin certain type of marble or limestone by causing pitting, spalling and yellowing. This is why it is important to protect the floor with a sealer (impregnator).


Sand and grit carried from outside by shoes can easily scratch and abrade the marble surface like a sandpaper. Unprotected furniture legs may leave scratches too. Dragging heavy objects or sharp items on the floor can cause very deep scratches or gouges that may be permanent.


Even a hard, natural stone such as granite is still porous and can easily be discolored by spills from food, sitting pots, metal furniture legs, oil, ink, water damage, etc.

Improper Maintenance procedure

Continuous use of water as the sole cleaning agent (without chemicals), or using dirty mops, or not changing the cleaning solution frequently enough, can cause soft and hard stone to look dingy, streaky and unattractive.

Improper Maintenance program

Not having a steady use of dust mop and damp mop cause a decrease of the gloss. In addition, a yearly maintenance may be required to revive the gloss especially when the floor is exposed to medium or heavy traffic.


Q33. What are the recommendations for a successful initial (basic) cleaning?

A. For floor/stairs(indoor)

1.Soft stone such as marble, limestone (not stable against acidic cleaner).

For contaminates such as basic dirt, dirt layers, thin layers of wax, superficial oil and grease stains, soot, rubber and tar stains, even efflorescence and cement rest

Clean with a light alkali cleaner (pH=10). Don’t start with the concentrate form. Depending on the dirtiness, start with a water dilution 1:5 to 1:25

2. Hard stone such as granite, gneiss (stable against acidic cleaners).

Clean with alkali cleaner as well as with acidic cleaner (pH=1). Because many of the hard stones such as the so-called “black granite” (Tiger Black, G684) are not stable, it is necessary to conduct a pre-treatment test with the acidic cleaner on an inconspicuous area. Do not use immediately in concentrated form and pre-wet the surface. Acidic cleaner based on hydrochloric acid react with many hard stones to cause rust. Other hard stones as Labrador lose their gloss immediately. Acidic cleaner based on acetic acid attacks the fittings.


B. For façade, wall terrace (outdoor)

1.Soft stone such as marble, limestone (not stable against acidic cleaner).

Clean with a light alkali cleaner (pH=10), algae & mildew remover, which is a slightly alkali cleaner (pH=11) based on active chlorine compounds. Use undiluted. Do not allow contact with plants, metal, wood and cloths.

2. Hard stone such as granite, gneiss (stable against acidic cleaners).

It is possible to clean with alkali cleaner as well as with acidic cleaner or/and algae & mildew remover


C.Kitchen-countertop, wash basin, sanitary items

1.Soft stone such as marble, limestone (not stable against acidic cleaner).

Clean with an alkali cleaner (pH=10)

2. Hard stone as granite, gneiss (stable against acidic cleaners.

Clean with a strong alkali cleaner (pH=12)


Q34. What are the recommendations for a successful daily cleaning?

It is usually not necessary to clean daily unless it is a high traffic area like hotel lobby, etc. For all floors the daily cleaning should be carried out by a cleaning product with pH= 7 neutral and water-based.

Clean with a neutral cleaner (pH=7) or stone soap. Surfaces are to be slightly moisted with a wiper to remove the dirt. Dilute the concentrated cleaner in water 1:50 to 1:100 and clean the surface with a slightly moistened cloth. Let the surface dry for 10 minutes. The products can also be used in a brush cleaning machine with a sucking device.

It is important to prevent the product from creating layers or stripes on the floor to support the protective effect of the impregnation. The water solution of the cleaning product should be applied with a mop. Dirty solutions should be mopped up regularly. Remove loose debris by sweeping or vacuuming before applying the cleaning solution.


Q35. Which are the recommendations for a successful periodical cleaning?

A.Periodical initial (basic) cleaning

Due to heavy traffic or other circumstances it can be necessary to carry out periodically an initial cleaning with a slightly alkaline cleaner. The application period depends on the grade of pollution; it can be carried out every 3-12 month.

The product has to be diluted with water approximately 1:20 up to 1:50 depending, on the degree of pollution

The product must not affect the impregnation of the stone.

The cleaning solution should be applied with a mop. Dirty solution should be mopped up regularly


B.Spot and stain cleaning

Although impregnation is used, it can be at times necessary to remove spots of heavy pollution and stains. If required, preferred products are:

Rust remover for granite or for marble, Oil- and Grease Remover, Algae- and Mildew Remover etc. Also, bleaches are typically oxidizing agents (they generate oxygen) and are useful in stain removal. Enzyme types are available which are non – hazardous.



Q36. How to protect natural stones used for highly strained surfaces as such as kitchentop, table top, bar counter etc.?


The surface of the natural stone has to be clean, stain free, dry and with enough absorption properties. Nowadays most of the natural stones are already treated in the factory. As a result, the stones show altered absorption properties. Therefore it is recommended to use an oil- and water-repellent, solvent-based impregnation. In any case is recommended to prepare a sample area in order to examine the efficiency of the impregnation

Due to the permanent contact of impregnation with foods, is essential that the protection is approved as being of food-safe quality.


Q37. How to clean and care natural stones used for highly strained surfaces as kitchen tops, table tops, bar counter etc.?

Cleaning and care:

If cleaned immediately, many food stains can be taken care of with a simple damp cloth. Once dried up or involving fat, stains and soiling can no longer be cleaned so easily. For such residues, mild cleaning products with oil- and fat-solvent qualities should be used. Products that are extremely alkaline or highly degreasing can, over the long-term, damage the stone’s impregnation. Many manufacturers offer spray cleaners that are easily applied. They have a cleaning and protecting component and therefore provide a removal of stains and protection of the stone in one single working step. If used regularly, the spray cleaners can prolong the interval time between subsequent impregnations.

At the first sight of dark stains caused by oil- and fat-containing food, an immediate reaction is essential. Among the most effective solutions are oil removal pastes. These cleaning products guarantee a long application time, an essential factor if pollutions need to be dissolved that are deep-seated within capillary structures of the stone. After the removal of stains the protective impregnation needs to be renewed.





Q38. How to remove stains from the surface of natural stone?

1. Soft stone such as marble, limestone (not stable against acidic cleaner).

If you have contaminates such as; basic dirt, dirt layers, thin layers of wax, superficial oil and grease stains, soot, rubber and tar stains, or even efflorescence and cement residue-

Remove with a light alkaline cleaner (pH=10).

What to do if you have superficial rust stains produced by ferrous substances or objects, such as fertilizers, tools, iron pasts etc.:-

Remove with a slightly alkali rust remover (pH=9)


2.Hard stone such as granite, gneiss (stable against acidic cleaners)

If you have rust and inorganic discoloration: to remove inorganic discolorations, such as rust stains, use Rust remover, a product based on phosphoric acid. It is important to make a test patch in an inconspicuous area to ensure that the surface is acid resistant.

If you have lime residues, rust marks and heavy soap residues: They can be removed with an organic acid based disinfectant cleaner with (pH=1)

Mortar, lime residue, efflorescence, cements films and other stubborn deposits on tiles or slabs:

They can be removed with an acid-based concrete film remover, which is free of hydrochloric acid.






Q39. What are the main mistakes in maintenance?

  1. Cleaning only with water
  2. Not replacing the cleaning solution
  3. Cleaning mop head is not kept clean
  4. Floor is not vacuumed or dusted enough
  5. Not using a door mat
  6. Using the wrong cleaning chemical
  7. Not having a planned program for maintenance


Q40. Are they some tips to avoid mistakes during maintenance?

Here are some useful tips:


Use walk – off mats:

To reduce the possibility of unsightly scratches and/or dulling of the marble or limestone floor, install walk off mats inside and outside all entry doorways. Good quality walk-off mats will remove sand and grit from the bottom of a person’s shoe that could otherwise badly scratch and dull the marble floor.


Dust Mop & Sweep Regularly:

Walk-off mats will reduce the amount of abrasive soils that can enter from shoes, however, they cannot completely eliminate all materials that can scratch or dull a stone surface. Many abrasive soils are generated inside the house like very small pieces of broken glass or porcelain, metal chips or flakes, or sand and dirt brought in/on clothing or other materials. Dust mopping and sweeping will help remove these abrasive contaminants. Use a clean, untreated and dry dust mop or fine bristle broom and dust pan to remove all dust, dirt and loose debris daily or as needed. This is the most important thing you can do to keep the stone surface looking new.


Utilizing a neutral non – residual water based stone cleaner or a slightly alkali cleaner, damp mop regularly. Spot cleaning can be accomplished by simply applying a small amount of this neutral cleaner to a soiled spot, lightly rubbing to dissolve the spot and remove with a clean damp sponge.


Don’t clean only with water

This can be very detrimental to your soft stone. Water contains chlorine, salts and other minerals that will diminish the shine if used on a regular basis. In addition, water doesn’t have the ability to cut through dirt and mainly dust will be removed. Utilize neutral, non-residual water based stone cleaner, damp mop regularly. Spot cleaning can be accomplished by simply applying a small amount of this neutral cleaner to a soiled spot, lightly rubbing to dissolve the spot and removing with a clean damp sponge.


Replace the cleaning solution frequently

Otherwise, it will leave streaks all over the stone surface and the grout joints (especially if they are light colour) will get dirty very rapidly. Whenever you notice that the cleaning solution becomes cloudy and dirty, immediately replace it with a fresh new solution


Keep the cleaning mop head always clean

By using mop or cloths that are soiled and dirty, you are actually tracking the dirt back into the floor and grout joints. Dirty mops can create streaks and an unattractive look. Keep the cloth or mop head clean all the time. Wash them thoroughly after you have finished the cleaning with neutral soap and warm water


Use the right cleaning chemicals

In case you use the wrong cleaning chemical you can ruin your stone floor very easily. Especially soft stones made from calcium carbonate are very sensitive to any acid or high alkaline chemicals. Do not use any tile cleaners, vinegar, ammonia, alcohol etc. Use only neutral cleaners that have pH 7.00 or slightly higher and were made specially for cleaning stone. In this way you prolong the stone life.


Make a planned program for maintenance

Designate the cleaning days and polishing dates and the days that you want to re-apply the protection depending on the abuse and foot traffic. Doing that will keep the floor well maintained.



Author: Dr. I. Pomakis, Director of Application Engineering AKEMI GmbH Germany

ACKNOWLEDGEMENT- WONASA would like to thank the company AKEMI ( www.akemi.de) for the preparation of this Guide.