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Historic Preservation - Technical Procedures

Spectitle:

Cork Tile: Characteristics, Uses And Problems

Procedure code:

0966001S

Source:

20Th Century Building Materials (Ed. Tom Jester, Nps)

Division:

Finishes

Section:

Resilient Tile Flooring

Last Modified:

02/24/2012

Details:

Cork Tile: Characteristics, Uses And Problems



CORK TILE: CHARACTERISTICS, USES AND PROBLEMS


This standard includes general information on the characteristics
and common uses of cork tile and identifies typical problems
associated with this material along with common causes of its
deterioration.

INTRODUCTION

Characteristics of cork tile:

-    a natural wood product

-    made from the ground outer bark of the cork oak tree

-    light weight

-    porous

-    physically resilient and chemically inert

-    good insulation properties

-    high compressive strength

-    low thermal conductivity

-    expands and contracts with temperature and moisture changes

-    moderately expensive

-    first manufactured in the U.S. in 1899.

-    originally, cork shavings were fused together using asphalt;
    the use of natural binders replaced this method when John
    Smith patented a process to melt cork resin under high heat in
    1892

-    the combination of intense heat and pressure enabled cork
    shavings to be fused together without a glue or binder

-    were generally sold unfinished; finish was provided by the
    customer after installation, generally consisting of sanding
    and waxing

-    a factory finish was available in the late 1920s

-    phenolic resin and urea resins were later added to strengthen
    the cork tiles

-    colors included three natural shades of brown - light, medium
    and dark; color variation depended on the time length for
    baking and the temperature used during that time; the greater
    the temperature and time baked, the darker the tile

-    available in 3/16" or 1/2" thick; typically square, oblong or
    rectangular

-    originally, a wide range of sizes were available, but
    eventually became standardized; most common sizes included
    9"x9" and 12"x12"


TYPICAL USES

Typical historical uses for cork include:

-    bottle stoppers

-    corkboard for insulation

-    commercial/institutional flooring in schools, libraries,
    public lobbies, churches, courthouse courtrooms, auditoriums,
    hospitals and museums

-    residential flooring

-    Armstrong Cork Company was one of the largest manufacturers of
    cork tile

-    commonly laid over a concrete floor and secured with nails to
    a fibrous layer of asbestos concrete and waterproof mastic

Typical current uses for cork tile include:

-    commercial/institutional flooring in schools, libraries,
    public lobbies, churches, auditoriums, hospitals and museums

-    residential flooring

-    commonly glued to the subfloor using a mastic or an elastic
    waterproof cement


NATURAL OR INHERENT PROBLEMS

-    moisture:  excessive moisture or damage can result in
    deterioration of the binder, causing the cork composition to
    loosen and eventually buckle - more common with wax finished
    tiles

-    fading:  exposure to sunlight and ultraviolet rays can result
    in fading, brittleness and drying of the cork


VANDALISM OR HUMAN-INDUCED PROBLEMS

-    abrasion:  surface abrasion, including scratches and gouges,
    can occur when the surface finish becomes worn, such as in
    high-traffic areas; the accumulation of dirt and grit in these
    gaps and pockets further contributes to the deterioration
    process

-    staining:  high porosity of cork makes it very susceptible to
    staining

-    unsuitable cleaners and solvents can cause deterioration of
    the cork; some include ammonia-based or sodium hydroxide-based
    cleaners, organic solvents, abrasives, and caustic cleaners

                         END OF SECTION