Monthly Archives: October 2014

Dealing with Stone Spall

Current trends in interior design are leading homeowners to choose more natural products for their homes. This includes the use of natural stone in many rooms of the home from the kitchen to the family room. These trends include the use of materials in a rustic or “natural” state, which has some homeowners turning to stones like slate and quartzite for their floors, walls, and countertops. These products are left naturally cleft, rather than machined. Naturally cleft stones like slate and quartzite have a tendency to spall after installation, which can be startling and distressing for some homeowners. Educating them on this occurrence can help them make better decisions for their homes.

Spall is the process of small pieces of the stone breaking away from the surface. This is a completely natural and normal occurrence in cleft stones, and does not mean a defect. Most spalling will stop by itself after about three months, or the length of time it takes for the stone to get settled into its new environment.

During the three months that the stone is spalling, it is not uncommon for the entire installation to be very dusty. Small flakes of stone may break or chip off particularly as the stone is being cleaned. In the case of natural cleft quartzite, the stone may appear to be sugary with small granules brushing off of the surface.

Because of the spall, special considerations should be made when natural cleft products are used in kitchens and other areas where food is prepared and eaten. Customers with allergies may also be bothered by the excessive amounts of dust that can be created when a stone is actively spalling.

Keeping the stone damp by applying a damp mop to it on a regular basis can help to cut down on some of the visible spall. Otherwise, it will stop on its own in time. Customers that may not enjoy the effect may want to consider another naturally finished stone instead.

Kitchen Counter Overhangs

Many homeowners using slab counters of granite, marble, and quartz in their kitchens also use these materials on breakfast bars and other seating areas. To make room for the chairs and the person seated there, the countertop needs to extend outward a certain amount past the cabinets or knee wall. Because granite and marble are stone and naturally hard and durable, homeowners may consider extending the counter well past the point of stability, where the stone could begin to bend or break.

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Most stone for countertops is sold in either 2cm or 3cm thicknesses. No 2cm counters should be extended past 6- to 8-inches without being reinforced with a steel plate below the stone, or with corbels coming off the counter to add support.

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3cm and thicker counters may be able to be extended 12-inches or more past the cabinets without support, but this depends largely on the stone. Very hard Class A stones such as Absolute Black can be extended 12 or more inches without issues. Some Class C and D stones, however, can’t be extended even 12-inches without eventually beginning to bend or break. In many installations, a level placed on this area of the counter after a few months of use will show that the stone is beginning to bend without the support that it needs.

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For homeowners that want to maintain a contemporary look in their kitchen without corbels or visible supports, the stone thickness can be increased for these counters to help support it. Otherwise, a thin sheet of stainless steel can be bolted to the top of the cabinets, extending to within 6-inches of the edge of the counter, and the stone can be installed on top to prevent the eventual bending and cracking of the counter.

For homeowners with formal, Country, and transitional kitchens, corbels or supports built into the cabinets can help prevent the counter from breaking over time.

Types of Limestone

Limestone is a popular material for many homeowners to use on their walls and floors. It has a soft, creamy finish, often with a matte surface that gives homes from Contemporary to Country a little extra detail and style. Limestone can be divided into two basic groups, each of which has its own general appearance and characteristics.

When most people think of limestone they are probably thinking of the sedimentary stone that formed on shell reefs. It’s made of mostly calcite, and may be studded with fossils.

This type of limestone can vary from very soft to moderately hard, and some types can even take a high polish. Regardless, every type of limestone in this class reacts negatively with acids and alkalines, so a spill of vinegar on the floor will result in a foaming action that will begin to dissolve the stone. Some limestones, such as Lagos Azul are so soft that even some types of hard water can eventually lead to pitting and etching of the stone surface.

A less recognized form of limestone is known as lithographic or French limestone. Quarried in the hills of France and Belgium, this limestone is much harder, and has a slightly different appearance. While smooth to the touch, this stone appears to be rough or studded with holes.

French limestone is much older than other forms, dating back to the Jurassic period. It’s made of plattenkalk deposits that split into thin sheets. It formed in stagnant, hypersaline lagoons, rather than shell reefs and does not have the same type of fossil studding.

It does react the same way to acids and alkalines, but it wears much longer and is much heartier than other types of limestone. It is not uncommon, in fact, to find French limestone floor tiles that have been reclaimed from centuries old farmhouses, and that still have centuries of use left in them.

Homeowners looking for a very hard, long lasting floor tile that has the matte, smooth beauty of limestone may want to consider French limestone as an alternative.

Comparing Natural Stone Finishes

Natural stone tiles and countertops are available in numerous finishes. There is often some confusion surrounding these finishes on the part of homeowners, usually stemming from the fact that the appearance of the stone can be so different, it inspires them to think that the use or maintenance of the stone is also different.

Regardless of finish, one stone finished in a variety of ways reacts the same, which homeowners need to understand to treat their stone appropriately.

Polished stone is created by grinding down the surface of the stone to a high shine. The stone will have a silky smooth finish and reflects light when polished. Because of this finish, any scratches in the stone are usually more noticeable, as is etching, because it dulls the surface of the stone. This can lead some homeowners to believe that polished stone is weaker.

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Honed stone has a smooth, matte finish and a crisp edge. Some stones are too soft to take a high polish, and may be honed instead. Other stones may be honed rather than polished to give them a more contemporary appearance. Honed stones don’t reflect light the way polished stones do, so they are less likely to show scratches and etching.

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Tumbled stone has been placed in a drum with sand, water, rocks, and pieces of concrete. This mixture is tumbled or revolved over and over until the stone has a worn, weathered appearance, often with fissures and pin holes in the surface and a worn, soft edge. This rough, worn appearance often makes the stone appear more rugged than it actually is. This combined with the fact that the stone does not show scratches, chips, or etching the way that other stones do often leads homeowners to believe that tumbled stone may be more durable than it actually is. It may be sealed less frequently or installed in higher traffic areas than some softer stones can withstand.

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By understanding that the finish of the stone affects only the appearance and not the function, homeowners can take better care of their stone, helping it last for a longer time.