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Product Knowledge Training Guide Stone Products Contents ♦ What are the differences in products • Granite • Marble • Travertine • Slate • Onyx • Limestone ♦ Applications and uses ♦ Care and maintenance ♦ Glossary of terms ♦ Selling Tips Granite Granite is an igneous rock, which was formed by slowly cooling pockets of magma (hot liquid) that was trapped beneath the earth’s surface. It is the result of about 570 million years in the making. Granite is an intrusive rock – it forms deep underground and consists of mainly feldspar and quartz. Granite is the hardest known material used in commercial and residential applications. Normally granite is classified in three different groups: • FINE GRAIN: Fine grain granites are those in which the feldspar crystals average about 1/16” - 1/8" in diameter. • MEDIUM GRAIN: Medium grain granites are those in which the feldspar crystals average about 1/4" in diameter. • COARSE GRAIN: Coarse grain granites are those in which feldspar crystals average 1/2", and greater diameter or several centimeters in maximum dimension. Coarse grain granites may have a lower density. To Identify Granite: • More granular in appearance that can easily be distinguished • Course and relatively consistent appearance • Dense with minimal pores • Generally minimal variation between tiles or slabs Common Finishes: • Polished, honed, flamed Facts: • 6.6 – 8.5 on MOHS hardness scale – very durable • Weather resistant • Crystals can be viewed with the naked eye Applications and uses: • Granite can be used anywhere: interior/exterior, counters, walls, fireplaces, showers/tubs/vanities, flooring and fountains. • Commercial applications: exterior cladding, steps, heavy traffic areas, sidewalks. Marble Marble is formed from limestone by heat and pressure in the earth’s crust. These forces cause the limestone to change in texture and makeup. Marble is a metamorphic rock, which means, “changed form”. This process took well over 540 million years. Marble is mostly made up of calcite – a mineral form of calcium carbonate. The purest calcite marble is white. The minerals that result from impurities is what gives marble such a wide variety of colors. To Identify Marble: • Distinguished veining and crystallization • Large tile to tile variation • Extensive color palette – from white to black Common Finishes: • Polished, honed, tumbled Facts: • 2.2 – 5.5 on MOHS hardness scale; relatively soft • Green and black marbles should not be installed in water areas • Not recommended for food service applications • Polish will not sustain if installed in an exterior application Applications and uses: • Marble can be used on interior applications for walls, fireplaces, shower/tub/vanities and flooring. • Commercial applications: interior walls, statues, heavy traffic flooring (with regular maintenance to maintain polish). Marble ♦ Marble Classification The Marble Soundness Classifications indicate what method and amount of repair and fabrication are necessary prior to or during installation, as based on standard trade practices. The terms: waxing (1), sticking (2), and filling (3) are common industry terms: (1) Waxing – Waxing refers to the practice of filling minor surface imperfections such as voids or sand holes with melted shellac, cabinetmaker’s wax or certain polyester compounds. It does not refer to the application of paste wax to make surfaces shinier. (2) Sticking – Sticking describes the butt edge repair of a broken piece, now generally done with dowels, cements, or epoxies. The pieces are “stuck” together; thus “sticking.” (3) Filling – Filling refers to the process of filling any surface voids with epoxy, cement, or resin. Filling is not intended to be noticeable to a great degree, perfectly color matched, or “glass” smooth. (4) Dry Vein - Dry veins are frequently mistakenly thought by consumers to be cracks or unnaturally occurring breaks in the stone. Dry Veins are described when a naturally occurring vein shows a separation between the different materials. (5) Fissures - Fissures are hairline cracks or grooves and are usually caused by oxidation of the stone. They typically do not affect the soundness of the stone. Soundness Group A (MIA 11.5.1) - Sound marbles with uniform and favorable working qualities: containing few geological flaws or voids, and subtle and consistent veining. They include completely metamorphosed limestone or dolostone, in which impurities such as clays and silt have reacted chemically with the calcite or dolomite to form other minerals. These stones have uniform working qualities, can be used on the exterior or interior, and do not require any filling or patching. Marble Soundness Group B (MIA 11.5.2) - Marbles similar in character to Group A, except that all the impurities have not changed into other minerals. Occasional small holes and voids are to be expected, and are characteristics of this group of marbles. The holes or voids are filled by the factory with epoxy, shellac, or polyester resin. Class B may be used on the exterior or interior. Soundness Group C (MIA 11.5.3) - Marbles with some variations in working qualities. Geological flaws, voids, veins, and lines of separation are common. Many of the impurities have not changed into other minerals, and metamorphosis is not complete. This is the largest and most colorful group of marbles, and also contains significant holes, voids, lines of separation, and structural flaws. It is standard practice to repair these variations by use of reinforcing, liners, sticking together, filling with resin or cement, fabricating corners or missing stone with terrazzo and resin, and doing all other work necessary to hold the stone together to yield a finished product that is usable for architectural purposes. On completion, most repairs are visible and apparent, with a difference in light reflection. They contain mesh, resin, epoxy, or fiberglass backing. With few exceptions, these marbles are not suitable for exterior installation. Soundness Group D (MIA 11.5.4) - Marbles similar to the preceding group, but con- taining a larger proportion of natural faults, maximum variations in working qualities, and requiring more of the same methods of finishing. Few stones carry this designation at this time; it is reserved for very laborious Group C stones. ♦ Special Notes Green Marbles Green marbles are not recommended for wet areas of your home, and they are not recommended to be used with water based adhesives during installation. Because of the unique mineral content in these marbles, the tiles will absorb the water and may have a tendency to curl or warp. With this dynamic in mind, the only way to prevent issues is to install it properly with a non-water based material such as epoxy. Resin Back Marbles The resin backings are designed to provide rigidity and to stabilize some of the more fragile stone types used on floors. These backings can be composed of polyester, urethane or epoxy. Some backings can include fiber-mesh scrims. The best results come from installing resin-backed stones with an epoxy-based adhesive. Slate Slate is a metamorphic rock. Most slate is formed below the earth’s surface by changes in the makeup and appearance of shale, which is a sedimentary rock. Shale consists of clay and fine particles of quartz. Heat from deep in the earth changes some of the clay in shale into mica and chlorite. Slate results when pressure created chiefly by mountain-forming movements in the earth’s crust squeezes the mica and other minerals into parallel layers. To Identify Slate: • Common colors: from grays and blacks to rusts and greens (many slates are multi-colored) • Large tile to tile color and surface variation • Slate has a layered appearance Common Finishes: • Natural cleft, gauged, ungauged, tumbled, honed, polished Facts: • 6.0 on MOHS hardness scale; very durable • Shaling (pieces falling off face) is common within the first 6 months of installation • Made up of mostly clay and shale (silt and clay); very dense Applications and uses: • Slate can be used in interior and exterior applications: walls, fireplaces, showers/tubs/vanities, flooring, fountains and backsplashes. • Commercial applications: roofing, exterior/interior cladding, trim accents and some flooring applications. Slate ♦ Slate - Interior Applications Characteristics In the industry there are various stones that go by the name “slate”, some of which include quartzite, shale, and schist. Although similar in appearance, these rocks vary in their formation, mineral content, and their advised applications. Most varieties of slate represent a wide spectrum of colors. Due to this high variation, no two tiles are alike and the stone will vary from batch to batch. It is impractical to attempt hand selecting the colors. Tiles that were cut out of the same block may consist of solid colors from opposite ends of the spectrum and may contain infinite combinations of movement. Flaking Slate is a foliated rock. The layers will have a tendency to flake post installation as the stone settles. Not only is there potential for additional colors of the stone to be exposed as a layer cleaves off, but the texture may also change as a result. This is not a defect of the stone, and eventually the flaking will stop. When used in wet applications where drains are present, it is recommended that a fine net be placed in the drain to catch the pieces of rock during the settling process. Rust It is not uncommon to see rust appear on slate as a result of iron and other minerals within the stone oxidizing from moisture. Oxidation is an inherent characteristic of many stones and must not be left untreated, as it may cause the stone to become brittle over time. Proper use of sealers as well as a water proofing membrane on the substrate will prevent this from happening. Absorption Slate’s absorption rate can be as low as .2%, which is often seen in slate roof tiles. Some variations; however, can be as absorbent as 10%. The absorption rate will vary between different types of slate.