Cork: What is it?
Cork is the bark of the cork oak (Quercus Suber L.), which means that it is 100% natural plant tissue. It consists of a honeycomb of microscopic cells filled with a air-like gas and coated mainly with suberin and lignin. Other compounds are identified in its chemical composition, although in less quantity, such as polysaccharides, ceroids and tannins.
A single cubic centimetre of cork contains almost 40 million cells - around 800 million in a single natural cork stopper.
Harvested every nine years, without any tree being felled during the process, cork gives rise to an endless array of products, from the traditional to the most innovative and unexpected. The main product is the cork stopper, but not all cork qualifies to be transformed into that noble object.
It takes each cork oak 25 years before it can be stripped for the first time and it is only from the third stripping (at 43 years of age) that the cork, then known as «amadia», has the high standard of quality required for producing cork stoppers. The first two harvests – the «virgin» cork and «secundeira» cork –, as well as that removed from the base of the tree, becomes the raw material for insulation, flooring and products for areas as diverse as construction, fashion, design, health, energy production and the aerospace industry.
The cork is harvested by specialized professionals, always between May and August, when the tree is at its most active phase of growth and it is easier to strip without damaging the trunk. The cork oak is the only tree whose bark regenerates, acquiring a smoother texture following each harvest. Over the course of its lifetime, which on average lasts 200 years, it may be stripped around 17 times.
Natural, versatile and sustainable
Cork is a raw material which is so perfect that no industrial or technological processes have yet been able to replicate.
Over 50% of its volume is air, which makes it very light - it weighs just 0.16 grams per cubic centimetre and can float.
ELASTIC AND COMPRESSIBLE
It is the only solid which, when compressed on one side, does not increase in volume on another; and as a result of its elasticity it is able to adapt, for example, to variations in temperature and pressure without suffering alterations.
IMPERMEABLE TO LIQUIDS AND GASES
Thanks to the suberin and ceroids contained in the cell walls, cork is practically impermeable to liquids and gases. Its resistance to moisture enables it to age without deteriorating.
THERMAL AND ACOUSTIC INSULATOR
Cork has low conductivity to heat, noise and vibration. This is because the gaseous components contained in cork are enclosed in small impermeable compartments, isolated from each other by a moisture-resistant substance.
Cork is also a natural fire retardant: it burns without a flame and does not emit toxic gases during combustion.
HIGHLY ABRASION RESISTANT
Cork is extremely resistant to abrasion and has a high friction coefficient. Thanks to its honeycomb structure, its resistance to impact or friction is greater than that of other hard surfaces.
Because cork does not absorb dust, it helps protect against allergies and does not pose a risk to asthma sufferers.
The natural texture of cork combines softness and flexibility to the touch with a naturally uneven surface. The variable degree of irregularity is given by the type of cork used and the finish chosen.