Cork's extraordinary properties derive from its distinctive cellular structure. A one inch cube of natural cork contains more than 200 million tiny air-filled pockets. Some 50% of cork is captive air, which results in excellent buoyancy, compressibility, elasticity, a high degree of imperviousness to both air and water penetration and low thermal conductivity.
Cork is noted for the following properties:
  • Lightness & Low Density – The cellular structure of cork makes it very lightweight, resulting in cork's celebrated buoyancy.
  • Impermeability – Cork is impermeable to both liquids and gases, giving it superior sealing capabilities.
  • Elasticity – Cork is pliable and rebounds well to original size and shape
  • Low conductivity – Cork has one of the best insulating values of any natural material, with very low conductivity of heat, sound or vibrations.
  • Durability – A high friction coefficient means cork will wear and wear.
  • Fire resistance – Cork has shown a remarkably high tolerance to heat.

Cork Institute of America