The loss of the high polish on certain marble and granite can be attributed to wear. This is especially true of marble since it is softer than granite. The bottom of ones shoe acts like sandpaper on a stone floor surface and over time years of use will wear the polish off. To prevent excessive wear it is important to keep the floor dust mopped, placed walk off mats at all entrances. To repair a worn stone surface, it will be necessary to have a professional hone and polish it.
The dull spot created when liquids containing acids are spilled on marble is called etching. Marble and limestone can etch. Granite is more acid-resistant and will rarely etch. To prevent etching, avoid using cleaners and chemicals that contain acids. Bathroom cleaners, toilet bowl cleaners and lemon cleaners commonly contain acids. Certain drinks and foods contain acids and will also etch. Light etching can be removed with a little marble polishing powder. Deep etching will require resurfacing of the stone.
All stone surfaces can become stained easily. Most foods, drinks, ink, oil and rust will stain marble if left on the surface for a long period of time. Once a stone becomes stained, it can be difficult to remove. To prevent staining clean the spilled material as soon as possible. Blot the spill with a clean paper towel or cloth. If this does not remove the stain then a process called “poulticing” may be needed. To prevent staining, sealing the stone with a good quality penetrating sealer is important.
It appears as a white powdery residue on the surface of the stone. It is a common condition on new stone installations or when the stone is exposed to a large quantity of water, such as flooding. This powder is a mineral salt from the setting bed. To remove efflorescence do not use water, buff the stone with a clean polishing pad or #0000 steel wool pad. The stone will continue to efflorescence until it is completely dry. This drying process can take several days to as long as one year.
SPALLING, FLAKING & PITTING
Spalling is when the stone develops small pits or when small pieces of stone are popping off the surface. This condition is common on stone exposed to large amounts of water or when deicing salts are used for ice removal. Like efflorescence, mineral salts are the cause for spalling and pitting. Instead of the salts depositing on the surface ( efflorescence ) they deposit below the surface of the stone, causing pressure within the stone and therefore the stone spalls, flakes or pits. Unfortunately once a stone begins to spall it is almost impossible to repair. It is recommended that the stone be replaced.
There are several reasons why a stone will turn yellow : Embedded dirt and grime can give the stone a yellow, dingy look. Waxes and other coatings can yellow with age. Certain stones will naturally yellow with age. This is caused by oxidation of iron within the stone and especially problematic with marbles. If the yellowing is caused by dirt or wax build up, clean the stone with an alkaline or cleaner or wax stripper. If the yellowing is the result of aged stone or iron oxidation, it cannot be removed.