Shopping for Tile and Stone
Shopping for Tile and Stone
First, let’s focus on ceramic tile. The American National Standards Institute (ANSI) together with the American Society of Testing and Materials (ASTM) establish guidelines and minimum performance levels for the manufacture of ceramic tile here in the United States. These standards can be helpful in choosing the right tile for our projects. The characteristics these guidelines establish are found under ANSI 137.1 (1988) and include:
Note: Where there is an ASTM number after the characteristic, that number represents the actual test involved.
SHAPES AND DIMENSIONS
Establishes the type of tile manufactured. For example: Ceramic Mosaic Tile, Quarry Tile, Paver Tile, Glazed Wall Tile, Glazed Ceramic Mosaic Tile, Glazed Quarry Tile, and Glazed Paver Tile. ANSI 137.1 (1988) also establishes standard trim sizes and shapes called an alphanumeric system. In this system a trim piece designated S4269 is a 2″ X 6″ surface bullnose regardless of who manufactured it.
Establishes whether a tile is classified as standard or second grade. Note that standard grade tiles pass a minimum inspection when viewed at a distance of 3′ while seconds pass at 10′. Also included in this category are specifications like: the tiles appearance (IE: the face and back of the tile, thickness (ASTM C499), facial dimensions (ASTM C499), warpage (ASTM C485), wedging (ASTM C502), electrical properties-conductive tile only (ASTM C 483), mounting-in the case of pre-mounted or pre-grouted tiles, and abrasive admixture-only when specified).
COEFFICIENT OF FRICTION (ASTM C 1028)
Establishes how much effort it takes to move an object across the face of the tile dry or wet. This is vitally important when choosing floor tile in an attempt to minimize slip and fall injuries. For example, the American with Disabilities Act (ADA) requires that floor surfaces be stable, firm, and slip resistant. Further, the Building Code for the City of Los Angeles, California (USA) requires that level surfaces have a COF of not less than 0.6 and ramps no less than 0.8 when tested.
WATER ABSORPTION (ASTM C 373)
Establishes whether a tile is Non-vitreous (absorbs more than 7% water), Semi-vitreous (absorbs between 3%-7% water), Vitreous (absorbs .5%-3% water), and impervious (absorbs less than .5% water). Note: these values can change depending on whether we are considering floor or wall tile. Water absorption is important for selecting tile or stone for a particular application especially in wet environments or in areas subject to freeze/thaw cycles.
BOND STRENGTH (ASTM C 482)
Establishes the tiles minimum bond strength in Portland Cement Mortar.
BREAKING STRENGTH (ASTM C 648)
Establishes the tiles minimum allowable breaking strength.
ABRASIVE HARDNESS (ASTM C 501)
Establishes the tiles surface abrasive hardness. This test establishes a whole number rating for the tile. This means simply that the higher the number, the harder the tiles surface.
CHEMICAL RESISTANCE (ASTM C 650)
Establishes the chemical resistance of the tested tile.
CRAZING (ASTM C 424)
Establishes the tiles glaze resistance to cracking when tested.
FREEZE/THAW RESISTANCE (ASTM C 1026)
Establishes the tiles ability to resist freeze thaw damage when tested.
IMPACT RESISTANCE (ASTM C 368-Modified)
Establishes the tiles resistance to chipping with an impact of a 1/16″ diameter striker.What is the single most important thing in considering what has been written above? The single most important thing is simply the question you should ask of your ceramic tile supplier:
Is this tile manufactured in accordance with the standards outlined in ANSI 137.1 1988)?
If the answer to this question is yes, you will be relying on the manufacturers and supplier’s reputation and honesty. For more on this subject, review the section concerning What Does Brand Mean to you.
Nevertheless, let’s look at other tests that can be accomplished that concern the selection of the right ceramic tile for your application. The following tests are found in the Ceramic Tile Association of America (CTIOA) report on Counter Top Glazed and Unglazed Ceramic Tile #CTIOA-81-7 (R-98):
Note: I left out the tests in the report that were redundant to ANSI 137.1 (1988).
MOHS SCALE SCRATCH TEST
Establishes the tiles ability to resist visible scratches to known minerals. Simply an attempt is made to scratch the surface and bisque of the tested tile using a MOHS testing kit. The kit has 10 minerals of gradually harder mineral points ranging from Talc #1 (the softest) to Diamond #10 (the hardest). The higher the Mohs scale number the harder the surface or bisque.
ACID RESISTANCE TEST
Establishes the tiles resistance to common household acids like oranges, lemons, fruits, and vegetables.
WATER PENETRATION THROUGH THE GLAZE
Establishes the tile glazes ability to resist water penetration.
Establishes the tiles ability to resist staining by common household products like mustard, ketchup, animal fat, and vegetable oil. Then the tiles ability to be cleaned using common household cleaning products.
MARKING RESISTANCE TO METALS
Establishes that the tile shall not retain marks made on its surface by common household utensils after cleaning with neutral pH cleaners.
This is the most common abrasion resistance test that can be encountered when shopping for tile. The Porcelain Enamel Institute (PEI) developed this test. Tiles are tested using their method and are given a rating for surface abrasion resistance. The following indicate the rating and their meaning:
PEI 0; Not recommended for floors at allPEI 1: Light duty floor
PEI 2 & 3: Medium duty floors
PEI 4: Heavy duty floors
PEI 5: Extra heavy duty floors
What if the tile you are considering is not manufactured within the United States? Quality tile is manufactured throughout the world. The tile manufactured abroad is made in the same way that American tile is. The manufacturing standards are covered under a different governing body. The International Organization for Standardization (ISO) is the International equivalent to our (United States) ANSI. They also have testing guidelines for the manufacture of tile.
The testing terminology under ISO differs from ANSI. For example, the best tile grade under ANSI is Standard Grade. The best tile under ISO is First Quality. However, the result is the same. By insuring that the tile you are considering complies with approved manufacturing guidelines, the right tile for the application can be purchased and installed. Remember that many international manufacturers will indicate whether or not their tile complies with ASNI standards when shipping tile to the United States. Ask your dealer!
Note: If tile is labeled Special Purpose or Decorative Tile, it need not comply with any guidelines set forth under ANSI or ISO. These tiles are in a class all their own, and are NOT subjected to testing as above, use care to insure these tile will perform in the area you have in mind.
Of all these tests and resulting questions, which are the most important?
Tile Doctor Tip: All of these tests can be important depending on the application the tile is intended for. The ceramic tile should comply with the guidelines set forth in ANSI 137.1 (1988), the ISO guidelines, or that the manufacturer/supplier attests to the tiles compliance. Additionally, any tests that would indicate the tiles suitability for the intended purpose be considered.