Cork is the bark of the cork oak tree (Quercus Suber, L), 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.

The chemical composition of cork includes various types of compounds:

Suberin (45%) is the main component which covers the walls of the cells and is responsible for its elasticity and compressibility;
Lignin (27%), forming the structure of the cell walls, is an insulating compound;
Polysaccharides (12%) are the components of the cell walls which give cork its texture;
Tannins (6%) are the polyphenolic compounds which give it colour, and help to protect and preserve the material;
Ceroids (6%) are the compounds responsible for its impermeability.
Ash (4%).
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.

Cork oak forests are characteristic of the countries of the Mediterranean basin which are influenced by the Atlantic Ocean (the Southern part of the Iberian Peninsular, Italy, France, Tunisia, Algeria and Morocco). The European Union is the biggest producer of cork in the world (over 80%) and Portugal in particular is the world’s largest exporter of cork, producing over 50% of all cork consumed. It also contains the largest area of cork oak forest in the world (730,000 hectares, equivalent to 33% of the world total). Such a delicate eco-system has been regarded as part of Portugal’s national heritage for centuries and this indigenous tree has been protected by law since 1209, when the first agricultural laws prohibited it from being felled and encouraged it to be grown and harvested. Portugal is also a leader in research, development and innovation in this sector, and stands out not only for the quantity of the cork produced but also for its excellent quality.
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 (www.portalflorestal.com).

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.

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