Cork is the bark of the cork oak tree (Quercus Suber), an organic material composed of an agglomeration of honeycomb-like cells, filled with a gaseous mixture similar to the air which makes up around 90% of its volume, covered in alternate layers of cellulose and suberin. Each cubic centimetre of cork contains on average 40 million cells.
Cultivation of cork oak forests and environmental, social and economic sustainability.
Cork is a 100% natural material which is ecological, recyclable and reusable. The concern in its cultivation and manufacture is always for sustainability.
By being extracted periodically from the trees without harming them in any way, cork manufacture promotes environmental, social and economic sustainability in the regions where it is produced. It also encourages reforestation of areas affected by the risk of desertification, keeping them clear and well-conserved. Cork oak forest represents an eco-system which is unique in the world, providing a home to many native species of fauna and flora. It is worth noting that 42 types of birds are dependent on it, including some rare and endangered species. It is estimated that cork oak forests provide habitat for 140 species of plants and 55 species of animals, possibly unequalled in Europe as a whole.
Apart from cork, it finest material, the whole oak tree is economically viable. Its fruit, the acorn, can be used for replanting and also to provide forage for animals and cooking oils; the leaves are also used as forage and as a natural fertilizer; foliage resulting from pruning and from trees at the end of their natural life provides firewood and charcoal; and from the tannins and naturally-occurring acids in the wood a variety of chemical products are made.
Complementing forestry and cork extraction, cork oak forest also provides space for other activities such as rambling, hunting, bee-keeping and the picking of mushrooms and aromatic and medicinal herbs, all helping the local economy.
Blessed with great longevity and an enormous capacity for regeneration, the average cork oak will live to between 150 and 200 years, but needs 25 to 30 years before its trunk is ready to produce cork and become profitable, for which it needs to gain a perimeter of 70cm and a height of 1.50m from the ground. During its lifetime the average cork oak will be stripped of its cork 16 times at intervals of 9 years, a job which is done very carefully by hand in order not to damage the tree or its surroundings. The first harvest, the desbóia, is when the virgin cork, still irregular in structure, is taken off. Only after the third cork harvest, at around 40 years of age, will the tree yield cork of superior quality which has reached its peak quality and properties.
The exploitation and production of cork products is a highly sustainable industry.
The manufacture of expanded agglomerate, for example, using only superheated steam and making use of generators powered entirely by the waste produced from the shredding of cork and cork remnants, results in an agglomerate made from the resins of the cork itself.
The whole cork transformation process generates almost no waste, as all the components have some economic value, either by being recycled or adding value. Waste from the production of cork stoppers is converted into granules and reused in agglomerates for coverings or insulation, in the manufacture of technical corks, or decorative items. Cork dust from this process can be used as a fuel, burnt to produce steam and/or energy used in the factory itself or sold to the electricity grid, due to the high energy content of this material. Cork dust can also be mixed with other products, such as coconut fiber or rubber, to give new products of added value.
The fact that cork products are used is also very important from an ecological point of view, because they are renewable, long-lasting and help to absorb CO2. It is also worth noting that cork oak from which the bark is periodically extracted produces between 250% and 400% more cork than it would if left untouched, thereby increasing CO2 capture (Gil, 1998).