Marble, granite, limestone and other decorative stone are durable materials that will last a lifetime. However, if not installed correctly or properly cared for problems may result that will shorten its life. The following are the most common problems that may occur. Following are the most common problems and suggested methods of correcting them:
Coatings: Coatings such as wax, acrylic and urethane block the pores of natural stone and do not allow vapor to escape out (does not allow it to “breathe”). This, coupled with stripping, can cause spalling. When the pores are blocked by wax or a non-penetrating sealer, the internal vapor seeks its nearest exit which could be a weak spot in the stone, causing cracks. In addition, coatings mask other problems such as heavy etching, cracks, and deep scratches. The best solution to this problem is to remove the coating and never use them again.
Crystal Damage/Stun Marks: Stun marks appear as white marks on the surface of the stone and are common in certain types of marble. These stuns are the result of tiny explosions inside the crystal of the stone. Pin point pressures placed on the marble cause these marks. Women’s high heels or blunt pointed instruments are common reasons for stun marks. This type of damage is sometimes very deep in the stone or may even go all the way through it. Stun marks can be difficult to remove. Grinding and/or honing can reduce the number of stuns, but some travel through the entire thickness of the stone. Grinding with coarse abrasives can remove or improve some but may not remove them completely. If grinding does not remove them, replacement of the damaged stone is the only alternative.
Deep Scratches: Deep scratches can usually be repaired by resurfacing with medium to coarse grit diamond abrasives.
Efflorescence: Efflorescence 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 effloresce until it is completely dry. This drying process can take several days to as long as one year. Do not seal the stone until any efflorescense is gone.
Etching: Etching is a dull area on the stone caused by spills of acidic products such as citrus juice, wine, vinegar, soft drinks, tile cleaners, and oxalic acid in powder polishes. Marble and limestone etch very easily. Granite is very acid-resistant and will rarely etch. If the etching is very light, it possibly can be repaired by polishing the area with polishing compound. Heavy etching must be repaired by resurfacing the area with diamond abrasives. To prevent etching, avoid using cleaners and chemicals that contain acids.
Lippage: Lippage is the term given to tiles that are set unevenly. In other words, the edge of one tile is higher than the next and is the result of a poor installation. If the lippage is higher than the thickness of a nickel, it is considered excessive and the tile will have to be ground down or beveled to alleviate the problem. This is done by grinding or resurfacing with coarse grit diamonds or abrasive stones. It is best to have this type of work done by a professional stone refinishing company.
Loss of shine: 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 much softer then granite. When shoes track in dirt and sand, the bottoms of the shoes can act like sandpaper on a stone floor surface and over time will wear the polish off. The shine can be restored with powders or compound or this can be done by a stone restoration professional.
Sanded Grout: Unfortunately, there is no immediate solution to the problem of sanded grout. Over time, the exposed sand at the surface of the grout may “smooth” off, but in the mean time you must make allowances for the problems it causes. Note: Marble and granite tiles generally have very thin grout lines. Terrazzo is poured in larger sections (4×8 ft.) and usually has metal expansion strips. While ceramic and porcelain will have 1/4″-1/2″ sanded grout lines the majority of the time.
Spalling, Chips and Holes: Small pits or small pieces of stone popping off the surface is called spalling. 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, causing stone spalls, flakes or pits. Spalling, chips and holes in the stone surface must be filled with a polyester, epoxy, or cement- based filler material with color added to match that of the stone. Generally, the area must also be resurfaced after filling to smooth out and level the filler material with the stone surface. Replacing the stones is another, but more costly alternative. Unfortunately once a stone begins to spall it is almost impossible to repair. It is recommended that the stone be replaced.
Staining: Some stone surfaces can become stained easily if they are not properly sealed. Many foods, drinks, ink, oil and rust can cause stains. Most stains on stone can be removed. For some, more difficult stains, professional techniques by a stone restoration provider may be the only hope. Permanent stains can occur but not often. For more information, see the Stain Removal section in this guide.
Water Rings/Spots: Water rings and spots are very common on marble and other natural stone surfaces. They are either areas that have become etched or are from hard water minerals such as calcium and magnesium that are left behind when water evaporates, leaving a ring or a spot. To remove either type of these spots, use a marble polishing compound. Moderate to severe etching or larger damaged areas will require professional honing by a stone restoration contractor.
Yellowing: The tendency of a light-colored stone to become “yellow” can be caused by several reasons. First, many white marbles contain iron that oxidizes over time causing the yellow appearance. This type cannot be repaired and replacement is the only answer. Most yellowing is caused by dirt that is ground into the stone or by wax type coatings that turn yellow. This type can usually be remedied by stripping or deep cleaning with a suitable alkaline cleaner or wax stripper.. Some yellowing may be the result of the use of steel wool during crystallizing when moisture is present. This type can be corrected by cleaning with ammonium bi-fluoride solution.