The cork oak in Sardinia – supplier of a renewable raw material

Cork – when you hear this word, you might think of the lovely sound of a cork popping out of a bottle, or of cork coasters, flooring and pinboards. But have you ever wondered where cork actually comes from?

Where do cork oaks grow?

This noble and useful material comes from cork oaks in the Mediterranean region, including the beautiful island of Sardinia. Many cork oaks grow there, and there are entire forests of these beautiful, gnarled trees. Around 70 to 80 per cent of Italian cork production comes from Sardinian forests.

The cork oak (Quercus Suber) is an evergreen deciduous tree and grows mainly in Portugal, Italy, Spain and parts of Algeria. Its bark provides the raw material for cork. The cork oak needs a lot of sun to produce high-quality cork, which is why it is at home in southern countries. It would be too cold for them here in Germany, as the tree is not winter hardy. Cork oaks have a life expectancy of 150-200 years when harvested. Otherwise, they can live up to 400 years.

How is cork produced?

After approximately 20 to 25 years, the oak trees are stripped for the first time during the summer months. This first stripping is called virgin bark. This bark is still very fissured and unsuitable for cork production. It is used almost exclusively for granulate production. Subsequent strippings are then more uniform and therefore of higher quality. They are used to make bottle corks. The stripping requires great care, as the mother layer, which protects the tree from drying out and infection, must not be damaged. In addition, the new bark grows underneath it.

A tree may only be stripped of a maximum of one third of its bark, otherwise it would dry out. After 9 to 11 years, a cork oak can be stripped again. This is a long period of time, which is monitored by the state. After 9 to 15 harvests, the cork oak is then exhausted. A tree can produce approximately 45 kg of cork per harvest. After harvesting, the cork bark is stored for 6 months to dry and stabilise. Before corks are manufactured, the bark is boiled in water. This kills insects, removes tannin (tanning agent) and makes the material soft and elastic. The cork then matures for approx. 6 weeks in darkness and at a specific humidity.

Bottle corks are drilled out of the cork sheets. This leaves behind the perforated sheets. These form the base material for compressed cork blocks and cork floor coverings.

In addition to harvesting cork bark, the forests are also used as woodland pasture for cattle, sheep and pigs.

What are the different uses of cork?

Cork, a buoyant and insulating material, has been a highly valued raw material for centuries: the Egyptians are said to have lined tombs and coffins with it to better preserve the remains of the deceased. The Romans sealed their wine containers with cork, a practice that is still common today. The Sardinians use cork containers and mats for food, or use the material to insulate walls and roofs.

In 1680, Benedictine monk Pierre Pérignon took advantage of the special properties of cork and produced the first special cork for a sparkling wine bottle. From the 18th century onwards, champagne bottles were primarily sealed with the corks invented by Dom Pérignon. As the production of non-sparkling wines also gained in importance, cork production experienced a tremendous boom.

The use of cork for souvenirs has increased significantly over the last four decades. In addition to mass-produced tourist items such as postcards with colourful Sardinian prints or cork-covered Sardinian mugs, you can also find handcrafted items such as traditional Sardinian masks, vases and jewellery boxes. Clothing is now also made from cork and is said to be comfortable to wear. Cork is the perfect material for fashionable clothing and accessories: it is soft, elegant, modern, washable, extremely robust and completely natural.

The cork oak in Sardinia awaits you.

But cork is also very beautiful in its living form. So don't miss out on a trip to one of the magnificent cork oak forests during your next stay in Sardinia!

With a Sardinian ‘Adiosu’, I bid you farewell for today.

Joachim Waßmann