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Quarry to Kitchen In recent years, several factors have affected freight costs. Fuel prices had been gradually rising long before Hurricane Katrina maimed Gulf Coast oil operations. And the trend toward greater use of shipping containers has made the handling of huge raw blocks disadvantageous, relative to previously inexpensive bulk shipment. With such trends in alignment, Brazilian suppliers have been successful in improving their share of product value by shifting toward the export of processed stone and finished products, rather than just the raw material. So although Brazil did export 13 percent more blocks and rough granite slabs in 2004 than in 2003, the value of processed granite slabs exported increased by 54 percent. Still, importing finished products included other frustrations and limitations, and BMG entered the market to overcome these. As an LPA, BMG purchases large volumes of material at a time, thereby lowering costs to its member companies and helping them to control quality and sell uniform products. Similarly, standardized production procedures help ensure relatively homogeneous items in every lot at every worksite. The members inspect each item instead of performing random checks. And they provide packaging that protects not only the product, but its handlers as well. Finished products are ready for use at their destinations, so they can be shipped from Brazil directly to a residential construction site. Use with Care Despite its beauty and durability, stone, like any material, has several potential disadvantages when used in building construction. Marbles and granites vary in absorption, and adjacent materials can stain both of them. For instance, sap in unseasoned plywood can bleed through facing stone, inappropriate nails in the plywood can rust and bleed, and a darker setting material can bleed through white or light-colored stone. Both granite and marble are quite slippery when wet, which restricts their use in flooring. Either crushed or flamed surface finishes are less slippery than burnished ones. However, producing these two rustic finishes creates minute fissures in the stone, thereby increasing its liquid absorption and its retention of dirt and pollutants. Marble and granite will stain if not thoroughly protected by a topical sealer or a subsurface impregnator that repels both water- and oil-based liquids. Removing a stain requires drawing it from the stone with a poultice. The National Training Center for Stone and Masonry Trades posts an extensive stain-removal guide. Polishing stone brings out its color, and granite surfaces are typically polished. Because granite is melted rock, it has uniform properties, which makes it quite hard and resistant to scratches. Granite is stain-resistant, but not stain-proof. Indeed, dark epoxy grouts can permanently stain the porous varieties. Marble is less abrasion-resistant than granite and more chemically reactive. Designers use marble with both polished and unpolished finishes. While the unpolished stone is soft and porous, highly polished marble scratches easily. In fact, even grouts containing sand can scratch marble tiles. Nonstaining mortars and flashing should be used with marble. Also, because it is sensitive to acid, typical acid-based grout cleaners should be avoided. Clean marble surfaces with soap or detergent of neutral-pH and water — never with diluted vinegar. White marbles are susceptible to oxidation, which turns them yellow, especially in the presence of moisture. Green, red, and black marble tiles contain minerals that will soften, blister, swell, or curl from water or moisture. These must be set in epoxy-based, rather than water-based, mortars. Even translucent marble, by allowing the transmission of light, will reveal shadows from any underlying colored bonding material. These potential problems may not come to mind as a designer specifies marble or granite for a countertop. With proper precautions, they can remain out of mind and out of sight. From Stonehenge and the Pantheon to the new Bibliotheca Alexandrina, the power of stone is ancient, modern, and timeless. Candace Nelson is a freelance journalist and editor. BMG provided travel assistance to facilitate this coverage. Discuss this article in the Architecture Forum...
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