Stone Care

01. What is the difference between cleaning normal and polishing?
02. What types of detergent are there?
03. What products should be used to polish floorings?
04. Which cleaning products should be avoided?
05. How can scale stains be removed?
06. Are water and oil repellent treatments important?
07. How can existing flooring be revived?
08. How can stubborn stains be removed?
09. What causes wear and deterioration of natural stone?

 

01. What is the difference between cleaning normal and polishing?

Cleaning means the removal of impurities, scale and deposits from the surface of natural materials using vacuum cleaners and then water with a neutral detergent (pH 7).
Polishing stone, on the other hand, means applying a wax to enhance shine (the level of light diffraction), exalt natural colors and protect the surface against natural deterioration caused by wear. Polishing with wax is applied to marble floors with a shiny surface finishing laid in interiors; it may also be applied to granite for protection purposes. Polishing agents are designed to brighten the colors and beauty of marbles, granites and stones by creating an attractive “wet-look”. The most common application in the home is with the classic polishing machine or by hand using woolen cloths for normal cleaning.
Resins and waxes also have a slightly protective function, since they create a surface stratum offering some resistance to the action of water and, to a lesser extent, oils.
If the flooring is exposed to significant walk-over traffic, it must be washed and rinsed daily with water and neutral detergents. Special attention must be paid to the removal of sandy and abrasive materials that may be carried indoors. Regular manual or mechanical polishing with the application of wax also has a protective and water-repellent effect that helps retain the original shine over time.

 

02. What types of detergent are there?

Normally, the detergent used must be neutral but in certain cases simple cleaning is not enough and different solutions such as ammonia or bleach must be used which are safe with all natural stones.
Detergents are chemical products used for cleaning and belong to different categories.
Acid-based compounds (such as muriatic/hydrochloric acid) are unsuitable for use with carbonate stones such as marble, decorative limestone, calcareous tuff, travertine and carbonate-matrix sandstone but can be used with silica-based stones such as granite, porphyry, serizzo and beola gneiss and quartzite.
Alkaline-based compounds, such as ammonia, are especially used for marble, ornamental limestone, calcareous tuff, travertine, carbonate-matrix sandstone and slate that are affected by acid-based products, and are naturally also excellent for granite.
Honed and polished surfaces should only be treated with low concentration products with acidity (pH) only slightly higher than neutral, while compact and less sensitive materials can be cleaned with concentrated solutions exerting a more drastic dilution action.
In all cases, after washing with alkaline- or acid-based solutions, the action of the detergent should always be inhibited by rinsing with water to restrict corrosive power.
Before applying detergents, tests to determine their effectiveness are recommended: there is the risk in the event of worn or highly porous surfaces that the detergent penetrates into the material and can no longer be removed by final washing-rinsing. Other detergents are specifically intended to eliminate rust stains, verdigris, cement and other stains.

 

03. What products should be used to polish floorings?

A Liquid Was is recommended to achieve a warm, dry and long-lasting polish. The best liquid wax has a concentration ensuring optimal dilution in water to ensure a significant improvement in yield. The wax must withstand walk-over traffic for considerable periods of time, not create halos and not contain resins that create ugly films.
If waxes are included in the composition, this improves the shine and durability with marbles and granites.

 

04. Which cleaning products should be avoided?

- Acid-based products (e.g. alcohol or muriatic/hydrochloric acid) have a corrosive and tarnishing effect on marble surfaces that spoils the polishing.
- Denatured alcohol has a pH of between 5.0 and 6.0 and since it is slightly acid must never be used as a detergent on calcareous natural stones such as marble, onyx, slate, travertine and sandstone. In the long term, alcohol spoils the polish through corrosion of the calcite content. If there are stubborn stains, it is possible to try and remove them using ammonia, which is basic.
- Never use detergents containing hydrofluoric acid (HF) with natural stones, including granites, since it can completely dissolve the quartz making up the silicates – not to mention limestone – or phosphoric acid.
- Anti-scale products: marble, travertine, slate and onyx are almost entirely made up of limestone and cavities would be formed after dissolution of the calcite. Granite, serpentines, serizzo gneiss and quartzite – since they are silicon-based – are resistant to common acid, although their use as a detergent is not recommended because the may cause corrosion or leave halos. In chemical terms, anti-scale products are strong acids and at times even contain phosphoric acid or hydrofluoric acid.
- Silicates such as granite, gneiss, serpentines, beola and serizzi gneiss and quartzite, on the other hand, are resistant to weak acids such as alcohol, vinegar and citric acid and even certain strong acids used in household cleaning such as muriatic/hydrochloric (sulfuric) acid. In any case, it is advisable to use strong acid only in extreme cases and after having first tried all other less caustic detergents.
- Even hydrochloric acid in some cases brings about color alterations or swelling in some silicates.

 

05. How can scale stains be removed?

Any scale deposits can be removed from natural stone using weak acid capable of dissolving calcium carbonate very slowly.
In these cases, it can be eliminated from marble and limestone in general using a weak acid such as citric acid or denatured alcohol diluted in plenty of water. A concentrated weak acid is ok for granites. Rinse the acid very carefully to halt the corrosive reaction. If high-impact treatment is needed for marble, use ammonia diluted as an ordinary detergent. In extreme cases, use household bleach with a whitening effect.

 

06. Are water and oil repellent treatments important?

It is important for all natural stones having a prevalent composition based on calcium carbonates – such as marble, travertine, onyx (alabaster), slate and breccia – to apply a protective water and oil repellent treatment to safeguard the surface, since even weak acid liquids such as lemon juice or drinks such as Coca Cola may cause stains that would be all the more evident on materials with a light and uniform color.
 Natural materials such as granite, quartzite, porphyry, serpentine and beola gneiss, on the other hand, are more resistant and less susceptible to chemical attack – although they may be corroded by some strong acids.
Marble and granite are also not entirely impermeable to water because of their porosity, with the consequent risk of saline efflorescence of salts diluted in water or the formation of yellow/reddish stains following oxidation of iron that is a typical problem with certain marbles, including Carrara white marble.
All these problems are solved by appropriate surface treatment to close microscopic porosity. It is good practice to repeat the water-oil repellent treatment every 6/12 months as routine maintenance to protect the material.
Preventive surface treatments are highly recommended to protect interior flooring and cladding against scale. Scale usually occurs in bathrooms because of the hardness of tap drinking water. In these cases, hydro-oil repellent surface treatment is also recommended to help prevent scale formation.

 

07. How can existing flooring be revived?

For old floorings, a wax remover helps eliminate all traces of old natural and synthetic waxes and resins that may have accumulated, as well as ingrained dirt without affecting the original polish of the material. For cleaning at regular intervals after eliminating old waxes, on the other hand, a commercially available detergent specific for marbles can be used.
In extreme cases, such as time-worn and deteriorated floorings, alkaline detergents (ammonia, bleach) diluted water may be used for a whitening effect – although it is in any case advisable to ask the opinion of an expert in such circumstances. It must be borne in mind that natural stones vary a great deal: exterior pavings in granite are extremely long-lasting, while polished white marble, on the other hand, is much more sensitive.

 

08. How can stubborn stains be removed?

Only mechanical action can remove the crust formed obstinate stains but leaves the mark caused by the penetration of staining material into the pores of the stone.
In such extreme cases, certain stones are unaffected by solvents such as trichloroethylene and turpentine, or even household cleaning products such as muriatic/hydrochloric acid: granite, serpentine, quartzite, beola and serizzo gneiss. It is advisable to try household ammonia first with marble.
If the stain is caused by using an anti-scale product on marble, alabaster, breccia, sandstone or slate, then this is not a stain as such but surface corrosion that requires re-polishing of the damaged portion. Granite, serpentine, quartzite, beole and serizzi gneiss, on the other hand, are unaffected.
All others stubborn and evident stains such as oil, industrial grease, food fats, coffee, etc. can be eliminated used paste-based products recently available on the market. They are specifically formulated to eliminate stains from stone materials and do not affect the polished, do not leave halos and help restore the original beauty of the material. The chemical composition helps absorb the most resistant and ingrained stains. They are applied using a spatula or similar tool to form a layer about 5 mm thick, which is then covered with a plastic film. After 2 or 3 hours, the plastic film is removed and after about 8-10 hours, depending on the ambient temperature, the powder is then removed using a brush.
At this stage, any substance used to remove stains must be eliminated by rinsing with water.
In any case, the elimination of such extreme stains is always experimental and it is strongly advised to perform a test on a small, hidden portion; the best advice in such cases is to ask the opinion of experts in natural stone materials.

 

09. What causes wear and deterioration of natural stone?

Exposure to agents of deterioration and wear on a continual basis varies in relation to
- use: maximum for exterior pavings, minimum for interior cladding
- chemical composition of the material: alabaster (known as onyx today) is mild and little resistant to chemical agents, while granites are hard, resistant to wear and are only affected by strong acids that may corrode them
- uniformity of color and shade: stains are very evident on uniform white materials and much less so on a dark multi-color marble
- surface processing: a shiny surface is always more delicate than natural quarry split processing
- climate, temperature, rainfall and wind are active agents affecting external applications
- air and rain water pollution for external applications; for interiors, special attention is needed in bathrooms since maintenance of the hot water circuit may involve corrosive liquids in the boiler and piping which then reach the bathroom itself. In such cases, the application of preventive protection treatments to close the pores of the material and make it impermeable to water-borne pollutants helps ensure optimal conservation.
Deteriorated flooring, even in more extreme cases when the surface of the material cannot be restored, may be revived by re-honing and re-polishing it with specific honing-polishing machines and coating cracks with a mastic of matching color.
When correctly cleaned, polished natural stone flooring retains its appearance for centuries without alteration or becoming opaque; pedestrian traffic helps keep it polished, as one can see in century-old pavings in churches or the porticos in Piazza Duomo, Milan, following continual abrasion.
If a material – typically marble – becomes opaque for any reason, it means it is losing it surface honing and protective treatment is advisable.