New tile manufacturing standard reflects modern market trends and tile testing
by Stephanie Samulski
August 6, 2008
Tile Q&A;
With approval by the American National Standards Institute
(ANSI) all but complete, our industry awaits implementation of the revised ANSI
A137.1 tile manufacturing standard, which better addresses the way ceramic tile
is manufactured, categorized and sold in the United States today. The
long-awaited changes to the twenty-year-old A137.1 standard have already been
passed by the Accredited Standards Committee on Ceramic Tile A108, a group of
experts representing all segments of the industry. Upon ANSI approval, the
industry benefits from a standard that more accurately conveys “what’s in the
box,” or what should be. The first in a three-part series, this article
provides an introduction to the standard and its purposes. Subsequent articles
will cover technical aspects more specifically.
What is ANSI A137.1?
The ANSI A137.1 standard defines various tile types and the
performance, under various tests, that can be expected. To do this, the
standard also specifies the tests used to measure performance and the number of
tiles required for each test.
For example, it’s important to know
how well the glaze of a floor tile will perform. Can it stand up to the heavy
traffic of an airport? Or should it only be used in a residential application?
By testing the glaze, a maximum service recommendation with regard to expected
traffic can be determined. The A137.1 standard requires that tile glaze be tested
using test method ASTM C1027. This test involves subjecting test tiles to
abrasives that are “swirled” around on their surface. The number of cycles that
a glaze withstands without showing wear determines its glaze wear rating (O –
V). This provides a means for consumers to easily compare an aspect of
performance among many tiles by many manufacturers. This glaze wear rating is
often inaccurately referred to as the PEI rating.
How many tile tests are included in A137.1?
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Table 4:Test
Classification
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There are 12 destructive tests and 9 non-destructive tests.
(See Table 4)
What tile types are defined in the proposed standard?
There are five: quarry tile, glazed wall tile, ceramic
mosaic tile, pressed floor tile and porcelain tile. They are defined as
follows:
- Quarry tile: glazed or unglazed tile made by the
extrusion process from natural clay or shale
- Glazed wall tile: A glazed tile with a body that
is suitable for interior use and which is usually non-vitreous, and is not
required nor expected to withstand excessive impact or be subjected to freezing
and thawing conditions.
- Ceramic mosaic tile: Tile, usually 1/4 inch to 3/8
inch thick (6.35 mm – 9.53 mm) and having a facial area of less than 9 square
inches. Such tiles are usually mounted in sheets or strips with other mosaic
tiles.
- Pressed floor tile: Floor tile manufactured by
having the body of the tile formed by pressing. Has a facial area of at least 9
square inches.
- Porcelain tile: a ceramic tile that has a water
absorption of 0.5% or less, as measured by ASTM C373, that is generally made by
the pressed or extruded method. Does not include materials with very little or
no crystallinity, such as glass tile.
Each tile type has its own set of performance testing
requirements that must be met in order to be labeled “A137.1.” For example,
glazed wall tile must have an average breaking strength of at least 125 lbf
(pounds of force), with no tile in the tested sample set breaking under less
than 100 lbf. Because they may be used on floors, all other tile types must
have an average breaking strength of at least 250 lbf, with no tile in the
sample breaking under less than 225 lbf.
The old A137.1 standard defined four
tile types. Pressed floor tile and porcelain tile previously fell into the
single category “paver tile.” Now, “paver tile” is only to be used as a general
term for floor tile, not in reference to a specific category of tile with
defined characteristics and performance requirements.
How many tiles are tested?
The number of tiles that must be tested is determined by the
test method and the sampling plan referenced in the standard. The sampling plan
is based on the Normal Sampling Plan, Level 2, at a 2.5% AQL, per ANSI/ASQ
Z1.4-2003. This is a sampling guideline that provides the number of samples
that should be tested, based on the size of a shipment or “lot.” It also
provides the number of samples that may fail a test with the lot still
considered acceptable.
For example, if 2 boxes of tile were
ordered for a backsplash, with each box containing 50 tiles, the lot would be
100 tiles. The Level 2 sampling plan requires that, for a lot containing 100
tiles, 20 tiles must be tested. Out of these 20 tiles, one of them may fail a
test and the lot would still be considered acceptable. If two tiles failed, the
lot would be rejected.
This example illustrates how
statistics are applied to tile testing to ensure tile shipments contain no more
than 2.5% imperfect tile. Although this allowance is quite stringent, it’s
still important for estimators, purchasers, consumers and installers to be
aware that a few tiles in a lot would not have to meet all aspects of
performance defined in the A137.1 standard for the lot to be acceptable. Where
the defects are in the facial appearance, the installer would be expected to
notice the defect and not use the tile, or the part of the tile with the
defect.
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