- Types of Natural Stone
Limestone is a layered sedimentary stone, and may include seashells and fossils. Most limestones have a granular texture. Their constituent grains range in size from microns to visible particles. In many cases, the grains are microscopic fragments of fossil animal shells. It is usually more uniform in color and pattern than marble and travertine. Limestone also tends to be softer than marble and travertine. Travertine is a banded variety of limestone that forms over time near waterfalls, hot or cold springs as it is formed by the minerals dissolved in ground water and deposited on to the earth’s surface by streams. Travertine is harder than limestone, and is more porous as the gas bubbles create a pitted structure in the stone. The pores can be filled with color matching putty to give the stone a smoother texture. Colors range from the most common beige to warm browns as well as grays, yellows and reds. Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. White in its purest form, most marbles come with swirls and veins in a variety of colors due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Marble is also used as the commercial name including all decorative calcium-rich rocks that can be polished, as well as certain serpentines or verd antiques. Basalt is the most common volcanic rock in the Earth’s crust. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It is a good heat insulator. Basalt has been used in construction as building blocks or for flooring and paving in public places. Recently has become more popular as a decorative item in contemporary architecture.
- Natural Stone Finishes
Natural stone may come in a wide range of finishes. Stone properties and project requirements play a vital role in choosing the right finish for the stone and application. Pera tile carries prevalent finishes for each stone type together with some innovative alternatives. Stone finishes included in our portfolio and their properties are listed below. Polished finish results in a shiny, smooth surface. A polished finish on the stone has a glossy surface that reflects light and emphasizes the color and marking of the material. This is the most common finish for marble, and somewhat has become popular for travertine recently. Both filled and unfilled travertine can be polished, although the filled and polished finish is more popular than unfilled and polished. Polished offers more surface protection against stains and dirts. Honed finish results in a matte, satin-like and smooth finish. This is the most popular finish for travertine and limestone, and can be applied to marble as well. Honing brings out the natural colors and variations of the stone as well, but in a more subtle way compared to polished look. Honing provides a less slippery surface compared to polishing. This makes honed finish the preferred choice in some flooring and outdoor applications. Honed / Polished & Filled finish is applied to stones with cavities and holes. Honing or polishing process is preceded by the filling process where the wholes and cavities especially on the surface is filled special compounds named as filler. Cement, epoxy and resin are widely used fillers. Cement is generally used for honed finish and, resin is used before polishing. Tumbled or antique finish is obtained by making the unfilled tiles go through an additional tumbling process. During this process, tiles are placed into a chamber with small rocks to obtain a smooth antique look with cushion edges. This process results in the stone looking more weathered and scuffed. If desired, the pores can be filed with epoxy or grout during installation. Brushed finish is a result of a brushing process that leaves the stone with an aged but still smooth, more structured look. Brushing exposes the hardness differences on the stone surface and results in a gentle embossed look. The tiles are usually unfilled, and most commonly come with a “chiseled edge” finish. In this edge finish, the edges of the tiles are hammered or broken to enhance the antique look. Splitface is obtained by literally dividing the stone into 2 by application of force parallel to the surface. Broken surface resembles the rough surface of a naturally broken rock. Recently split face products have become very popular for wall decoration with their rough and natural look. Generally smaller dimensions are used for interior decoration and larger split face products are used in cladding. Bush Hammered is an ancient treatment for shaping the stone and providing a non-slippery surface. In bush hammering the surface of the stone is hammered by a sharp metal leaving small marks, ditches and craters on stone surface. This surface treatment is preferred in external applications, pools and stairs due to its non-slippery characteristics. Bush hammering also neutralizes colors, somewhat whitens the colored stones and decreases the sharpness of the movement. Some designers prefer bush hammering due to this aesthetical effect which makes it very attractive for cladding or flooring applications where less contrast and delicate look is demanded. Flamed is a high temperature heat treatment of the surface of the stone. Flaming is apllicaple mostly to granite, and only to a hanful of marble and limestone. Flaming results in relief, rough, cratered surface which provides a rustic look to the stone. Flamed stones are less slippery.
- General Stone Care
Natural stone surfaces, such as granite and marble, are hardwearing and one of the easiest to maintain. Proper care is necessary, however, to keep the surface looking new and avoid stains and etching. By following a few simple guidelines, you can ensure that your surface gleams and shines longer. Protecting Your Stone Surface: Use coasters under all glasses because many common foods or drinks contain acids that will etch or dull the surface of many stones. Do not place hot items directly on the stone surfaces. Sealing: Sealing is the first step in any maintenance plan. The right seal will help protect the surface and prevent stains. Most stone will need to be sealed and then resealed annually. The type of sealer will depend on the surface preparation and the density and porosity of the stone. Cleaning: Clean interior floors frequently using a clean non-treated dry dust mop. Sand dirt and grit do the most damage to natural stone surfaces due to their abrasiveness. Always wipe up spills and messes immediately using a soft cloth or sponge. The longer a substance sits on the surface the more damaging they become. Do not allow water to sit on the surface as it can cause mineral deposits such as calcium, salt, or lime to build up on the surface. Choose the Right Cleanser: For best results, only use pH-balanced cleansers, one that has a neutral pH level of 7.0, on natural stone. The term “pH” refers to the level of acidity or alkalinity in a solution. Cleansers that are high in alkaline are baking soda (pH 9), bleach (pH 11) and ammonia (pH 11). Cleansers that are highly acidic are lemon juice (pH 2.4) and vinegar (2.8). Alkaline and acidic cleansers can remove the natural polish and seal of the stone’s surface. This can make the surface dull and allow new stains to penetrate and set more easily. Most detergents and dishwashing liquid will work as they usually have a pH level of about 6.5. However, you will want to check to make sure that it does not contain any of the above ingredients, which can raise or lower the pH level. Clean stone surfaces with a few drops of neutral cleaner, stone soap or mild liquid dishwashing detergent and warm water. Do not use products that contain lemon, vinegar or other acids on marble or travertine. Do not use any acidic-based, alkaline, soft paste, or window cleaners. Also, avoid cleansers that contain vinegar, alcohol, lemon juice, and ammonia. Do not use any abrasive cleaning pads such as steel wool, metal brushes, or scouring powders. Scrubbing: Occasional scrubbing may be necessary to remove surface build up of dirt or grime. Honed and slate surfaces will require scrubbing more often because their texture can hold dirt. Dealing with Stains: You may choose to use a heavy-duty cleanser or a poultice. Poultice, a paste-like product, that can either draws the stain out of the stone or pushes it down into the stone away from the surface. To use, it is applied to the surface, covered with a piece of plastic, and allowed to set. Whenever these products are used, it is important to follow the manufacturer’s directions carefully. Otherwise, you could end up doing more damage to the surface or permanently setting the stain. Heavy-duty cleansers are usually highly acidic or alkaline and should only be used as a last resort. It is also important to choose cleansers from a good manufacturer and test it in an inconspicuous area first. Polishing stones and pads can be purchased at most local hardware stores and will help fix damage done by chemicals. There are also kits available that have several polishing products in one box. These should only be used for small areas. Larger areas should be handled by a professional.
- Stone Glossary
Cross Cut: The process of cutting the initial block of stone parallel to the natural bedding plane. The effect is a mottled or cloudlike appearance. Vein Cut: A cut into quarried stone perpendicular to the natural bedding plane. Result in traceable veining structure resembling patterns and veins of wooden products. Resin: A chemical product, clear to translucent, used in some coating and filling processes. Resin covers the fills and or the surface of the stone and when polished provides a glossy look. Paver: A single unit of fabricated stone for use as an exterior paving material. Book Match Pattern: A combination resulting in a mirror like repetition of the natural pattern of stone. Book match pattern is obtained by joining two stone surfaces one of which is rotated 180 degrees and both are cut adjacent to each other. Bullnose: Convex rounding of a stone member, such as a stair tread. Chiseled Edge: A process of mechanically chipping the tile edge, thus giving the stone a rustic, aged appearance. Eased Edge: Softened edges as opposed to sharp square edges for added safety. Moldings: Decorative stone deviating from a plane surface by projections, curved profiles, recesses or any combination thereof. Ogee: A stone molding with a reverse curved edge: concave above, convex below. Pillowed: A tile finish that features softly rounded edges, thus giving the tile a pillowed look.
Throughout human history, stone has maintained a reputation of both durability and elegance. Some structures which have come to be known by many people as icons of human achievement were made with stone, proving that marble is a very “civilized” choice, as well as one that is simply tasteful. Just as in ancient Greek and Roman society, marble represents beauty, elegance, sophistication in our modern era. It has become an increasingly popular choice for interior and exterior decoration. Pera Tile carries a variety of different natural stones in a multitude of finishes. Below are brief descriptions of major types of stone and finish.