There are numerous classifications in the stone-floor category. Granite, quartzite, serpentine, marble, limestone, travertine, sandstone, terrazzo and agglomerate are generally what we see. These classifications exist because of differing characteristics in the individual stones. The geologic classification, composition, hardness, and porosity help to determine chemical selection and cleaning methodology to be used. It is important to understand that although stone floors are rocks, they are not indestructible or immune to the damaging effects of some chemicals.

The surface texture will have a significant impact on the hard-floor maintenance program's design. Thermal or flame-cut textures leave the stone with a rough surface. The texture has low areas in which dirt will accumulate, making it difficult to clean. A honed finish has a dull matte look and, even though it has an even surface appearance, it is still somewhat rough and will collect soil in the low areas. A polished finish is very smooth and does well repelling dirt because there are no low areas to collect dirt.

The high gloss of a polished stone surface in a traffic area will appear dirty and dull in time due to erosion. The primary cause is tiny superficial scratches created by soil, sand and grit. These microscopic particles constantly are constantly ground into the floor surface. Some will get trapped into the pores of the stone while others will move around and erode the surface. Although all stone floors are exposed to these erosive conditions, some withstand the attack better than others.

The daily/routine maintenance of stone floors in general is basically the same. The Marble Institute of America's recommendation for all stone floors is to dry mop them to remove the grit, wash with a neutral detergent, rinse with clean water and buff out with a soft pad. Periodic and salvage/restorative maintenance is where changes in maintenance methodology occur.

Maintaining Marble Floor Coverings
Calcareous stone floor coverings, sometimes called the calcium carbonate stones, consist of marble, limestone and travertine. They are similar in composition with a hardness rating of 2.5 - 5.5 on the Mohs scale and therefore are maintained in the same manner. These floor coverings may be damaged by certain types of acid and are generally less resistant to strong alkaline chemicals. They are also more susceptible to staining by grease, oil and rust because of their porosity. There are methods for removing stains and restoring damaged stone, but these are advanced techniques that require certification training.

Marble
One of the most common stone floors is a metamorphic (re-crystallized) limestone called marble. This calcium carbonate contains primarily calcite and dolomite, and is most commonly identified by veining and crystalline texture. It has a wide range of colors and can be found in many of the most prestigious buildings in the world.

Marble is probably the most well known of all the natural stone floors and has been around for literally thousands of years. The existence of marble floors today in some of the world’s most ancient structures is a testament to their ability to endure. Marble is a metamorphic limestone, which is to say that it has been crystallized by heat, and pressure. True marble in its purest form is white. Cracks that occur in the young life of the limestone allow different minerals in. The discoloration that these minerals cause is what gives us that veined appearance that we so strongly associate with marble.

Today's commercial marble is defined as any stone other than granite that will take a polish, so what you assume is marble may in fact be something else. Marble comes in hundreds if not thousands of different colors and patterns.

Limestone
Limestone is a sedimentary rock composed of calcium carbonate that comes from the shells and skeletons of ancient sea creatures that settled on the bottom of giant inland seas. They generally consist of calcite and dolomite, but some may contain other minerals such as magnesium carbonate, which affects the hardness of the stone.

Limestone is very similar in appearance to marble because it is, in fact, adolescent marble. It differs from marble in that it has more of a uniform appearance, with slight color variations, and is generally not veined. It will, however, have a bedding plane with possible shell or fossil fragments caused during the process of its formation. Most limestone used for floors is light cream or tan in color, occasionally yellowish.

Travertine
Travertine limestone is a sedimentary rock formed in pools by the mineral-rich water found in springs. The calcium carbonate in the water deposits on the edges and build dams. These dams continue to grow until the water finds a different path or discontinues, the dams remain, and precipitation occurs, which ultimately becomes travertine. It has a fine crystalline texture, and has properties that are very similar to marble.

Travertine hard enough to take a polish is classified as travertine marble. The most recognizable aspect of travertine is that it is a layered structure with pores and pits formed from tiny creatures decaying. Water movement and algae that once grew in these deposits created these various-sized voids. Travertine is generally tan or cream colored with a definitive bedding plane.

The voids in travertine are normally filled with synthetic fillers. The fillers eliminate voids, which can become soil collectors. On occasion you will encounter a travertine floor where the filler has been omitted. This can become an extremely difficult maintenance situation.

Initial Maintenance
Initial maintenance for marble, limestone and travertine floor coverings will vary slightly depending on the level of gloss the customer is expecting. Marble floor coverings are usually honed to a matte finish or polished to a high gloss. On occasion you might find a floor that has a thermal cut finish, but these are not common. Tiles are usually honed or polished at the quarry and are shipped ready for installation. If the tiles were installed correctly, dust mopping and wet mopping to clean up the installation soiling may be all that is necessary. If the stone is to be polished onsite, a specialist of the construction contractor will generally do it.

After the initial cleaning maintenance, a penetrating seal or impregnator may be applied to the floor surface to reduce the penetration of water, oil and other liquid spills. Once this is accomplished the floor is ready for the specified maintenance.

Initial maintenance may also include the use of a powder polish and the polishing service procedure to aid in protection and gloss. In other situations, the crystallization service procedure may be used to protect and enhance the appearance. Many times the customer may have the contractor apply aqueous, or water-based, coatings on the floor, even though this is not a recommended maintenance method for stone-type floors.

Daily/Routine Maintenance
As with all hard floor surfaces, daily/routine sweeping or dust mopping of the floor keeps dust and grit from accumulating. The frequency of the dry-service procedure will fluctuate, depending on the assessment criteria. Environment and traffic conditions within the facility dictate the frequency of the service. In some situations, multiple repetitions of the dry-service procedure throughout the day may be required.

Marble, limestone and travertine floors should be wet mopped with neutral detergent or approved stone-maintenance cleaners on a daily/routine basis. Manufacturer dilution ratios should be used accordingly. The classification of the mopping procedure will be determined by the type and amount of soil to be removed. Of course, all liquid spills should be spot mopped up as they occur.

For light to moderate traffic, remove superficial soil using the damp-mopping service procedure. Moderately soiled floors can be cleaned using the wet-mopping service procedure. When the floors become heavily soiled, the aggressive mopping service procedure will be in order. Strategically scheduling the different mopping service procedures has the potential of extending the periodic cleaning schedule.

Periodic Maintenance
In many situations it may be necessary to machine-scrub the floor on a periodic basis. When the mopping procedures no longer produce the results desired, machine scrubbing may be the option. Generally, the light-scrubbing service procedure will remove most soils; however, the medium-scrubbing service procedure may be required for more stubborn soils. Most synthetic pads are safe to use on stone floors, with the exception of high-productivity pads and stripping pads; choose the softest pad that will perform the service you desire.

There will be times when a stone floor may have been sealed or finished. If the stone floor is using an aqueous chemical-coating system, the machine-scrubbing service procedures may be required periodically. The classification of the scrubbing service procedure to be scheduled will be dictated by the areas soil conditions. Always rinse the floor well after any periodic cleaning to remove any detergent or alkali residue. Additional coats of floor finish may need to be applied after the cleaning.

Polishing of the floor will be required on a periodic basis. The method of polishing will vary depending on the maintenance system selected for the floor. Diamond abrasives, crystallization and powder polishing are the generally accepted methods for maintaining marble. These are three very distinct systems that require training and certification to ensure optimum results.

Salvage/Restorative Maintenance
Salvage/restorative maintenance for stone floors will incorporate the use of diamond abrasives. The types of diamonds required will be determined by the type of stone to be honed or polished. Diamond disks have abrasives that span grit sizes of 60 (very coarse) to 3,500 (very fine). The level of gloss desired will dictate the diamond abrasives required.

The salvage/restorative operation may require several levels of abrasives to be used to attain the desired gloss level. In addition to diamond abrasives, powder polish or crystallization applications may be applied after the diamond polishing. The salvage/restorative operation using diamond abrasives will last approximately five to seven years, depending on the maintenance program.

Again, if the stone floor has aqueous floor-coating chemicals on it, they will have to be removed using the stripping and refinishing service procedure. When coatings are used on stone floors, the surface of the stone will be scratched in the process of removing the old seal and finish. This is normal; the scratches will be covered when new coats are applied. If, however, the customer would like to switch to penetrating seals, crystallization procedures, powder polishes or creams, it will be necessary to utilize diamond abrasives first to remove the scratches.

The frequency of performing the stripping and refinishing service procedure will depend on the chemical coating and environmental conditions the floor is subjected to. Most strip-and-refinish situations on stone floors can last one to two years, and in some situations, even longer.

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