Stone Selections

Now lets look at stone tiles and their selection. Remembering that stone tiles are produced in nature, their color and general appearance may vary greatly. This makes stone tile quite unique and beautiful when installed correctly. Each stone type and its composition have characteristics that need to be considered for each application. For example, some stone is soft and easily abraded. There are types of stone tiles that are easily attacked by common household acids. Finally, there are very hard stone types virtually impervious to these same problems.

The Marble Institute of America (MIA) www.marble-institute.com publishes a manual for stone tile selection and testing. This manual establishes guidelines for selection based on current industry practices and testing established by ASTM. Like the standards and testing available for ceramic tile, stone tile is tested for many of the same characteristics. The characteristics of each stone tile make it possible to select the right stone tile for each application.

What type of stone is available in tile form? The most common stone tiles are:

• Marble
  
• Granite
  
• Limestone
  
• Travertine
  
• Quartz-based
  
• Slate

STONE APPLICATIONS

MARBLE: Flooring, Fireplaces, Vanities, and Shower/Tub surrounds.

Note: Black and green marble require special setting material due to their tendency to curl and wrap when absorbing water. Polished marble is not recommended in food preparation areas or any areas where contact with acids bearing substances are present. Acid even in small amounts will etch and dull the polish. This includes bathrooms below toilets and urinals where the marble will remain unprotected by mats, ETC.

The exception for marble in the food preparation areas would involve the use of "tumbled" marble where there is not a polished surface for the acid to etch.

Keep in mind that polished marble is very slick when wet.

Penetrative sealing is recommended.

GRANITE: (Basically on any surface). Flooring, Vanities, Kitchen counters, Fireplaces, Shower/Tub surrounds.

Keep in mind that polished granite is very slick when wet.

Penetrative sealing in recommended.

LIMESTONE: Flooring and Fireplaces.

Sensitive to acidic attack.

Penetrative and or sacrificial sealing recommended.

TRAVERTINE: Flooring, Fireplaces, and Vanities.

This type of stone, in polished form, is sensitive to acidic attack just like marble. So it would not be recommended for food service areas or where acid bearing substances are present. The exception would be in a "tumbled" form where no polished surface is present to be etched.

Polished travertine is very slick when wet.

Penetrative sealing is recommended.

QUARTZ BASED: Flooring, Fireplaces, Bar tops, Vanities, Shower/Tub surrounds.

Very similar to slate in that flaking and chipping will occur especially in the un-gauged variety. May not be suitable in areas where bare feet may be present due to chipping and flaking.

Note: "Gauged" simply means that the stone has been honed to a consistent thickness and surface texture during the manufacturing process. "Gauged" stone products are more expensive and have a decidedly different look than their "un-gauged" cousins.

This variety of stone is commonly stabilized into agglomerates with cementitious or epoxy based resins to produce slabs and tile shapes. In this form, the Manufacturer will make recommendations for its use.

Penetrative and or sacrificial sealing is recommended.

SLATE: Flooring, Fireplaces, Bar tops, Vanities, Shower/Tub surrounds.

Just like the quartz-based stone, un-gauged slate is prone to chipping, flaking and peeling. This can make cleaning, disinfecting, and general maintenance problematic. Design and job requirements will have to reflect these inherent qualities.

Penetrative and or sacrificial sealing is recommended.

Dr's Tip: Bear in mind that all of the aforementioned descriptions and recommendations are general in nature. All design and job requirements need to be evaluated carefully and each level of the intended project.

All of these stone tiles are available in a wide array of sizes and colors.

When evaluating marble tile, it is helpful to know how the MIA has classified this type of stone. The classification deals mainly with the ease or difficulty in the actual use of the classified marble. The veins that you see in some stone like marble, limestone, and travertine are formed by the stone formation in the earth. This is called metamorphosis. The veins, while beautiful and decorative, can be weakened spots within the tile. These weakened spots, or faults can make cutting and setting of the tile more difficult. This leads us to the classification of this type of stone tile.

Marble Tile Classifications

Remember, the grouping should not eliminate the use of the particular stone tile, it simply means that more difficulty may be encountered in their use.

The testing for stone tile include important aspects like:

COEFFICIENT OF FRICTION-SLIP RESISTANCE (ASTM C 1028)
The same test is used for ceramic tile.

WATER ABSORPTION (ASTM C 97)
Establishes the amount of water a specific type of stone tile will absorb.

BREAKING STRENGTH-BENDING STRENGTH-FLEXURAL STRENGTH (ASTM C 99, C 120-Slate and C 880)
Establishes the strength of certain stone tile types to resist breakage or rupture under load.

ABRASIVE HARDNESS-ABRASION RESISTANCE (ASTM C 241)
Establishes the ability of certain stone tiles to resist abrasion. This test centers on stone tile intended for floor use.

Remember that many of the tests that are conducted on ceramic tile can also be used on stone tile. The important consideration is that the proper stone tile is matched with the installation requirements. Be sure to ask the manufacturer or supplier if the stone tile you are considering is suitable for your intended application.

So what’s the bottom line when considering ceramic or stone tile? There are not many hard and fast rules on tile selection. There are, however, some cautions. Any surface suitable to receive and support a tile surface can be tiled with virtually any tile type. However, if you intend that surface to be functional, durable, beautiful, and as low maintenance as possible, the right tile must be selected and installed properly.

Next>>