What every stone Owner should know .03

WHY DOES STONE SHINE?

When stone becomes dull and scratched, it obviously loses its shine and luster. At this time the stone needs to be refinished and polished to restore the shine it had originally. Why does stone shine, and how can a lost shine be recovered?

All stone is taken from the earth in the form of raw blocks. Explosives, large saws and specialized equipment are used to extract the stone from the earth. The stone blocks are then cut into thinner, more easily handled pieces called slabs. The slab itself is then processed, depending on the intended use of the stone. It may be given a high shine and shipped to a marble fabricator, who will ultimately turn it into a table, vanity top or whatever; or it may be transformed by some very expensive and sophisticated equipment into tiles for installation on floors or walls.

The deep shine we see on polished stone is achieved by rubbing the stone with a series of abrasive materials. The process is very similar to sanding a piece of wood. The stone is rubbed with coarse abrasive grit, followed by finer and finer grits until the stone becomes smooth. The next, creating finer and finer scratches remove the previous. The process continues until the scratches are microscopic. The shine on the stone is achieved by abrading the surface to the point at which it becomes extremely smooth and starts to develop some reflectivity. The shine on the stone is thus a product of optics. This same optical property can be observed on a pond. When the wind is blowing and the surface of the pond is wavy, it becomes difficult to see a reflection; when the air is still and the pond is calm, a deep reflection can be observed. So in order to achieve a deep shine on your stone, all that really needs to be done is to smooth it until it shines.

Sounds simple enough, doesn't it? Unfortunately, the techniques employed to achieve this degree of smoothness require special knowledge and training. This is not friendly territory for the do-it-yourselfer.

	Abrasive Abrasive: There are two types of abrasives, loose and bonded. Loose abrasives can be used to hone any de-lipped surface and should not be used on any uneven surface. Loose abrasives will not work well in moderate to heavy traffic areas. They work great on counter tops. Loose abrasives are sold in a powder form. Bonded abrasives can be used to remove lips from the surface. Choosing the correct bond is very important. They are sold in metal, copper, and resin bond. To remove lippage the metal will work best. But they are very aggressive. Copper will work on lippage but it will take about 25% more time to complete the same task. If the surface was already de-lipped the copper will remove deep scratches from the surface. Resin is the least aggressive of the bonded abrasives. Resin bonds won’t remove lips. However, they work well on light traffic areas.

	grit GRIT SIZE: Applies to the size and number of particles per square inch which are used to determine the abrasiveness of sandpapers, grinding stones etc.

	Marble MARBLE: CHARACTERISTICS This standard includes general information on the characteristics and common uses of marble and identifies typical problems associated with the material. INTRODUCTION Marble is an extremely hard, metamorphic stone composed of calcite (CaCO3). It is formed as a result of the recrystallization of limestone under the intense pressure and heat of geologic processes. The effect of this process is the creation of a stone with a very tight crystalline structure and small but definite porosity. Because of its structure, marble can take a very high polish and is a very popular decorative stone for architectural and sculptural uses. The limited porosity of marble, especially polished marble, makes it less vulnerable to the leaching effects of water. Calcium carbonate, however, of which marble is composed, is highly susceptible to attack by acidic agents. Marble is readily dissolved by acids, even very dilute acids, however the actual results of acidic exposure will vary with the nature of the acid. Chlorides, nitrates, sulfates and other chemical compounds react differently with marble and produce various by-products, which have a wide range of solubility and impact on the durability of marble. For this reason, it is always important to determine the exact type of pollutants causing marble deterioration. Marble itself can be of two types, one composed of calcite and the other of dolomite. Dolomitic marble is much more resistant to acid attack than calcite marble. The color of marble ranges from the brilliant white of calcite to black, including blue-gray, red, yellow and green, depending upon the mineral composition. TYPICAL USES Marble has many decorative and structural uses. It is used for outdoor sculpture as well as for sculpture bases; in architecture it is used in exterior walls and veneers, flooring, decorative features, stairways and walkways. The way in which the stone is used may be a factor in limiting or controlling the severity of exposure. The use or function of the marble may also affect the feasibility of applying certain treatments, but type of use is not the primary factor in the major types of deterioration and damage to which marble is susceptible.