Technical Info & Warranty is continued from previous page.
I MAGINE WHAT'S POSSIBLE
2 0 1 6 N E W P R O D U C T C ATA LO G
below. This is a common and expected occurrence in travertine flooring, and several return visits
to the installation will be required to fill these voids as they appear.
Pinholes in Marble:
On a much smaller scale than the voids found in travertine, many marbles
may have pinholes visible in the face of the material. Frequency can be as high as 100 or more per
square foot. This is not considered a defect, but rather a natural characteristic of the material.
Excessive Depth of Thinset:
Many stone varieties, particularly the softer marbles, limestones,
and travertines, are extremely vulnerable to non-uniform shrinkage of thinset adhesives. The
shrinkage during cure of the thinset can actually warp the tile enough to produce an extremely
fine, although visible, crack in the stone. Extreme care should be exercised in substrate prep
and installation to provide a uniform depth of thinset adhesive that is within the minimum and
maximum depths prescribed by the adhesive manufacturer.
Proper Bedding Area:
Natural stones are more vulnerable to cracking as a result of voids in the
setting bed than most ceramic products. Back-buttering of the stone tile is essential, and the
minimum acceptable bedding area is 95% contact with no voids exceeding 2 in and no voids
within 2" of tile corners on 3/8" tile. The minimum acceptable bedding area is 80% contact with
no voids exceeding 4 in and no voids within 2" of tile corners on " or thicker material. All
corners and edges of stone tiles must always be fully supported and contact shall always be a
minimum of 95% in water-susceptible conditions.
Grout Dye Staining:
The use of dyes in grouts should always be tested to verify that the dyes will
not leach into the stone, causing a "picture frame" stain. This is most common when using grouts
of contrasting color, although grouts dyed with matching color to the stone have been known to
cause staining in some instances.
The use of natural stones in environments where acid exposure is likely requires
a proper stone selection to avoid attack to the stone. Most notably, the calcium carbonate and
calcite based stones will react to relatively mild acids, such as lemon juice, vinegar, and sliced
tomatoes. The result is not a stain, which could be removed, but an etching of the stone surface,
which cannot be removed without refinishing the stone. In polished finish stones, a mild acid
attack will usually manifest itself as a "dull" spot within the surrounding glossy surface.
Many stone varieties have pronounced bedding planes, along which a
predetermined "rift" exists. "Rift" is defined simply as the direction along which a stone is
most easily split. Bedding planes can be a region of weakness, and some stones, particularly
sandstones and some slates, will actually delaminate along inter-bedding plane boundaries
after installation. This will result in a portion of the stone thickness separating and dislodging
itself from the rest of the stone, and is not related to any failure in adhesive, since the bonded
portion of the stone remains in place. Research is required to verify the adequacy of the stone
material for the intended application. Differential mineral expansion due to weathering and
thermal cycles tend to accelerate this occurrence, and freeze/thaw cycling is obviously an
Lot Specific Issues:
Being products of nature, stones are subject to the variability of any product
harvested from nature. Some stone deposits are remarkably uniform through hundreds of feet of
depth times vast lateral distances. There are cases of replacement pieces having been quarried
to repair or extend building decades old, and the replacements matched the existing nearly
seamlessly. In contradiction to these examples, there are quarries where the inter-block, and
even intra-block variability are so great that a given lot of material cannot be matched one
month later. In such cases, extreme care is necessary to ensure that adequate quantities are
ordered, including requirements for waste, breakage, and attic stock.
Lippage vs Grinding in Place:
Lippage in stone tile flooring is accentuated from what would
be perceived in a ceramic tile flooring for several reasons. Natural stones tend to be installed
with tighter joints, they typically have extremely slight, or no chamfer at their edges, and many
natural stones are provided in a very high gloss, polished surface finish. Industry standards
limit lippage between adjacent units of smooth finished natural stone flooring to 1/32", which is
approximately the thickness of a standard, plastic credit card. When this is not achieved, there
is the option of grinding the stone tiles in place to eliminate the lippage. This work is to be done
by skilled, experienced technicians, as care must be taken to avoid a "wavy" looking finished
floor. In some cases, installing contractors will plan to grind the finished floor regardless of the
lippage amount, usually per the requirement of the client. Lippage should still be minimized to
the extent possible during installation to avoid extremely thin stone sections after grinding.
Requirement for Pre-soaking:
Installing high porosity stones in hot, dry climates often requires
that the stone be pre-soaked prior to installation. Failure to do so can result in the stone wicking
excessive amounts of water out of the setting bed, leaving the bed with inadequate water to
accomplish proper hydration of the cements.
May occur in some white or very lightly colored marbles and onyxes having a
crystal structure that will transmit light to varying degrees depending upon stone thickness and
finish. Translucence can be an aesthetically intriguing decorative attribute.
Mixing Types of Materials:
Designs calling for a mixture of stones with different physical
properties, while aesthetically interesting, can give rise to problems of wear and of maintenance,
mainly on floor areas. Re-polishing will pose problems, should that need arise. The Specifier
should be aware that mixing types of stones means there will be different abrasion resistance
levels as well as different densities of stones that must be considered in the long term
maintenance of the stone and its wearability.
A stone may turn yellow due to dirt or soap scum set in it. Waxes and other types of
coatings can also yellow with age. Certain stones will naturally yellow with age as a result of
oxidation of the iron within the stone. This is especially true with white marbles.
Some stones, and specifically slates, contain deposits of minerals that can react to
moisture. Stone bleeding or rusting is a common example of this. Caution should be used in
installations where slate would be exposed to standing, run off water or too much humidity. As
water works its way through the stone, if the stone contains iron oxide, some of it may liquefy.
This iron will eventually surface through the stone and deposit itself on the surface of the stone.
The rust will return over time and may have to be cleaned periodically.
MOST COMMON STONE FINISHES:
Mirror gloss, with sharp reflections.
Dull sheen, without reflections, achieved by abrasive heads. The degree of honing
depends on the stone, but may vary from light to heavy. Generally, it is recommended that
a natural stone floor receive a honed rather than a highly polished finish in commercial
applications. Etching, scratching, and traffic paths will be far less obvious on a honed surface,
thus making for easier maintenance.
Flamed or Thermal:
Plane surface with flame finish applied at high temperature by mechanically
controlled means to ensure uniformity; changes the color of the stone.
Gives a more uniform, textured finish and allows more of the natural color to
Coarse plane surface produced by blasting an abrasive, allowing a fine-textured
finish; may lighten the color.
Coarsely textured surface produced by hammering, and may vary according
to the metallic head used, from fine point to very coarse, and may leave high, lighter-colored
A cleavage face formed when the stone is split into any thickness.
Method of putting tiles in a mixing container with sand and rotating them, allowing
the edges and corners of the tiles to chip. This method is used to give an antique and old look.
This finish is created by using specific brushes to give the stone a softer, aged look.
When stones are brushed, micro-veins open up. With traffic, brushed stones will increase their
patina naturally and more veins may open up.
Done by a machine, usually with circular abrasives to grind the material to a specific
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