The easiest and least expensive way to maintain a marble floor is through daily housekeeping. First, catch dirt, water, and ice-melting salts at the door by placing large mats with waterproof backings at all entrances; salt dissolves and pits marble. Second, keep the floor clean of superficial dirt by using a minimum amount of plain water (warm is best) and a cotton string mop. Frequent mopping will help prevent soil from penetrating the surface. Whenever possible, quickly blot spills, especially oil and grease, to minimize their absorption into the stone.
According to both Lina Gottesman, President of Altus Metal & marble Maintenance, and James Hunt, Manager of Port Morris marble & Metal Restoration & Maintenance Corporation, the use of detergents for routine cleaning is not recommended as they tend to dull polished marble and many contain chemicals that are best to avoid. For general griminess, add a minuscule amount of ammonia to water — so little that no odor should be present when diluted (less than 0.005 percent by volume). Alternatively, use extremely dilute solutions of a mild, neutral pH detergent such as dishwashing liquid, first testing it on a small area of the marble to be cleaned.
Periodic Professional Care
Periodic honing and polishing by a floor maintenance contractor will maintain the lustre and more importantly, significantly inhibit resoiling and deterioration. Mechanical honing with fine screens creates a smooth surface, followed by buffing to a polished finish with slightly abrasive putty and synthetic felt or wool pads. This may be done monthly or quarterly, depending on the wear the floor receives and the quality of finish the congregation desires. Daily in-house maintenance is crucial to the durability of the polished finish and saves money by reducing deterioration and the need for more extensive professional treatment.
If a marble floor is scratched, deeply soiled, or has a build-up of yellowed wax or discolored sealers, the lustre and natural color can be restored by wet sanding and chemical stripping. This messy, noisy process requires protection of workers with proper gear and temporary protection of adjacent surfaces, such as pews, doors, base moldings, and floor-mounted fixtures. Sanding is followed by honing and polishing. Repeated heavy sanding can noticeably wear down a floor, producing visible depressions; thus it is best to avoid the need (and the expense) of this procedure by maintaining the polished finish.
Sealers: To Use or Not?
The application of floor sealer intended to protect stone is controversial. Certain features are attractive, such as slip resistance and their ability to inhibit penetration of dirt, food, and beverage stains. A major disadvantage is the surface abrasion, expense, and nuisance of wet sanding and chemical stripping required to remove sealer when their appearance becomes undesirable due to discoloration, spotting, and uneven wear. Ms. Gottesman says that the most common complaint about floor sealers is spotting from water and salts during wet weather. Another problem is their tendency to darken white marble. Many proessional cleaning contractors and building conservators recommend leaving marble floors in their natural state without coatings. If floor sealers are being considered, evaluate the long-term maintenance costs and make sure to test the products during the winter on a small area near a door entrance.
Specific Cleaning Problems
Marble floors are frequently stained by iron, bronze, copper, oil and grease, ink, tobacco, and smoke. Always use the gentlest means possible to clean marble. Never attempt to remove stains or deposits by scraping, scouring, or indiscriminately applying bleaching agents, liquid marble cleaners, or other harsh chemicals. Damage such as rust stains may not appear until months later. In addition, all acids are potentially harmful to marble surfaces. Experienced marble cleaning contractors can select appropriate poultices (smooth pastes applied to the marble which dissolves the staining matter) for specific stains. For large-scale cleaning and stain removal on floors and walls, consult with a conservator to determine the appropriate test procedure and to develop specifications that can be used to solicit bids from qualified contractors.
* Acetone (nail polish remover) is sometimes recommended for cleaning natural marble. DO NOT use it on cultured marble, however, as it will damage the protective gel coating.
* Never use metal scrubbers on marble.
* Cultured marble is less delicate but still requires careful cleaning to avoid deep scratches or damage.