Cork Characteristics

Cork Characteristics

Cork is the outer bark of the evergreen cork oak (Quercus suber). This variety of oak grows mainly in Portugal, Spain, southern France, Italy, and the Maghreb. It consists of a tight web of up to 40 million cells per cubic centimetre. The cell membranes retain gas, giving cork its capacity to float, insulate and re-expand quickly after compression.

Cork is natural, recyclable and biodegradable. No natural or man-made material replicates its properties. In a world of growing environmental awareness, the cork oak survives without the use of chemical herbicides, fertilisers or irrigation. Moreover, it’s the only tree that regenerates after harvesting.

Cork renews itself naturally, as cork oak barkgrows 1.0 to 1.5 millimetres each year retaininga huge amount of CO2 from the atmosphereduring his growth.

Once the trunk’s circumference has reached 70 centimetres, the cork can be stripped. The tree is then harvested in regular cycles throughout its lifespan, usually over 150 years. Each cork oak provides an average of 16 bark strippings.

Traditional harvesting methods allow the cork oak to thrive without the use of synthetic herbicides, fertilisers or irrigation.The stripping, when done by professional loggers, does not harm the tree, because the first layer of reproduction cork merges with the continuously developing virgin layer in the unstripped part of the tree. To keep the trees in good health, government laws regulate the harvesting of cork oaks. Trees are harvested in cycles of not less than nine years.

Cork retains unique qualities of flexibility, elasticity and compressibility. Its extreme resilience, impermeability, lightness and insulating efficiency make it ideal for a large number of applications, such as a closure for wine and spirits, cork is used in industries as diverse as floors (floating floor and cork tiles), shoe manufacturing, construction (insulator planks), automotives (gaskets), leisure (fishing rods), upholstery (cork textile) and a wide range of cork finished articles (handbags, wallets, accessories).

Wine and cork are two products that have long been
companions, but few may know that this ecological, versatile and
raw material history goes back to 3000 BC.


Despite its many different uses, for centuries the most faithful ambassador of cork to the world has been the natural cork stopper, that seal of exceptional quality that is still today preferred and demanded by the great wine producers. However, throughout History there have been numerous references to this product and its varied applications. In 3000 BC, cork was already being used in fishing tackle in China, Egypt, Babylon and Persia. In Italy remains dating from the 4th century BC have been found that include artefacts such as floats, stoppers for casks, women’s footwear and roofing materials. Also dating from that period is one of the first references to the cork oak, by the Greek philosopher Theophrastus who, in his botanical treatises, referred in wonder to “the ability that this tree has to renew its bark after it has been removed”.

Wine and cork are two products that have longbeen companions. Proof of this is an amphora from the 1st century BC found in Ephesus: it was not only was sealed with a cork stopper but also still contained wine.

Later, in the 1st century CE, the Roman naturalist Pliny the Elder made extensive reference to cork oaks in his celebrated Natural History. He explained that in Greece the trees were adored as symbols of liberty and honour, for which reason only priests were allowed to cut them down. In the same work, we can read that cork oaks were consecrated to the god of Olympus, Jupiter, and their leaves and branches were used to crown victorious athletes. In Pompeii, the Roman city destroyed by the brutal eruption of Mount Vesuvius, wine amphorae sealed with cork have also been found.

Portugal can be proud to have been a pioneer in environmental legislation, the first agrarian laws protecting cork forests having been enacted in the early 13th century, in 1209. 

Later, during the Age of Discoveries, the builders of the Portuguese ships and caravels that set sail in search of new worlds used cork oak wood for the parts that were most exposed to inclement weather.They claimed that the “sôvaro”, as it was called then, was the best wood for masts and yards: besides being exceptionally strong, it never rotted.

Delicately-balanced ecosystems, cork oak forests
are a rare and valuable natural treasure only to be found
in the Mediterranean region.


Cork oak forests are delicately-balanced ecosystems, very specific that persist only in the Mediterranean region (Algeria and Morocco) and particularly in the south of Europe as in Portugal, where is the largest cork oak tree area (around 730 thousand hectares representing 33% of the whole cork in the world).

Considered a national heritage, cork oak forests have been legally protected for centuries (Decree-Law 169/2001). The trees may not be cut down and incentives are available for the planting and management of cork oak forests. This initiative, pioneered by Portugal, was clearly a good decision, since the harvesting of cork has become an industry of great economic importance and Portugal has become the main international cork exporter.

In Portugal, cork oak forests represent around 21% of the total forested area and are responsible for the production of more than 50% of the cork consumed throughout the world. This forests have species designated by Quercus (Quercus National Association for Nature Conservation) – large areas of holm oak (Quercus rotundifolia), small areas of Pyrenean oak (Quercus pyrenaica) and, above all, cork oaks (Quercus suber L). Of the entire flora in cork oak forests, the cork oak is the most numerous specie and can be found throughout the country, from Minho in the north to the Algarve in the south, except in the harshest areas of Trás-os-Montes and the coldest hilltops and slopes of north Portugal. However, cork oaks are most commonly associated with the landscape of the Alentejo, where they indeed grow on a large scale.