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These
physical properties provide cork all the famous advantages:
BUOYANCY: Light weight: Due to the fact that more than 50 % of
the cell volume of a cork piece consists of air, cork is one of the lightest
solid substances, with a specific gravity of .25.
COMPRESSIBILITY: A cubic inch of cork can withstand as great a
pressure as 14,000 lbs. per square inch without breaking, and retains
90% of its original form after the pressure is released. Less or more
normal pressure increase return to original form from 97% to 100%.
RESILIENCY: Because heavy pressure does not break down or destroy
the tiny air cells, but compresses the air within the cells, the cork
begins to spring back when the pressure is removed. A roll or sheet of
composition cork can be compressed in one direction without losing its
dimensions in the other direction. This is of great importance for many
applications of composition cork.
RESISTANCE TO MOISTURE AND LIQUID PENETRATION: While cork is not
completely impervious to moisture penetration, its cellular structure
gives it a high resistance to penetration by water which with the addition
of the proper binder can be proofed.
FRICTIONAL QUALITY: Cork is a highly frictional material, both
in its natural form as well as in cork composition. Even when wet or coated
with oil or grease, cork retains this quality which surpasses that of
leather, rubber, and many other products used for frictional or non-skid
purposes.
LOW THERMAL CONDUCTIVITY: Next to a vacuum, a "dead"
air space minutely divides one of the most efficient non-conductors of
heat. The cell construction of cork provides this property for which cork
is so famous.
ABILITY TO ABSORB VIBRATION: Cork, with its 200 million air cells
per cubic inch; of which 50% is air, essentially acts as an "air
cushion", absorbing vibrations and direct impacts.
STABILITY: Cork is a tough, durable substance with remarkable capacity
for retaining its initial properties wherever recommended. The high degree
of stability under varying conditions is paramount to the continuing success
and use of cork in the world today. |
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