Spalling is the development of small pits or small pieces of stone that are popping off of the surface. This condition is common on stone exposed to large amounts of water and 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, they deposit below the surface of the stone. This causes pressure within the stone; therefore, the stone spalls, flakes, or pits.
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 is especially problematic with white marbles. If the yellowing is caused by dirt or buildup, clean the stone with an alkaline cleaner or wax stripper. If the yellowing is the result of aged stone, or iron oxidation, it is not coming out.
Lippage is the term given to tiles that are set unevenly. In other words, the edge of one tile is higher than the next. Lippage is the result of poor installation. If the lippage is higher than the thickness of a nickel, it is considered excessive. The tile will have to be ground to flatten the floor.
Settling, poor installation, and excessive vibration are the causes for cracks in stone tiles. Sometimes cracks can be repaired by using a color-matched polyester or epoxy filler. Before a crack is repaired, it is wise to find out how, and why, the crack occurred in the first place. Otherwise it may recur.
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. Pinpoint pressures placed on the marble cause these marks. Woman’s high heels, or blunt pointed instruments, are common reasons for stun marks. Stun marks can be difficult to remove. Grinding and/or honing can reduce a number of stuns, but some travel through the entire thickness of the stone and are, therefore, impossible to remove.
Water rings and spots are very common on marble tabletops. These spots are hard-water minerals, such as calcium and magnesium. These minerals are left behind when the water evaporates, leaving a ring or a spot. To remove these spots, use a marble-polishing powder. Deep spots may require honing. To prevent spots on counters and tabletops, frequently apply a good penetrating stone seal.