What is cork?

What is cork?

Cork comes from the cork oak. This tree grows in the western part of the Mediterranean basin. In 2017, 34% of cork oaks were in Portugal (Portugal also produces more than 70% of the world's cork), 27% in Spain, 18% in Morocco and 11% in Algeria. They are also found in Tunisia, in the South of France and on the west coast of Italy. Cork forests are called "dehesa" and form unique natural ecosystems. The trees provide shelter for animals, retain moisture in the soil and prevent its erosion. Cork forests also form natural firebreaks.

It is the only tree whose bark can be stripped without it dying, so it doesn't need to be felled. The bark regenerates after each harvest. To do this, it stores CO2 and turns it into cork through photosynthesis (1 kg of cork absorbs 50 kg of CO2). This makes the cork oak one of the species that absorbs the most CO2.

What are the properties of cork?

Cork has many properties, which it keeps in its various forms.

It is a friction-resistant material. Naturally water-repellent and rot-proof, it can be used as a durable thermal, acoustic and electrical insulator. Being antistatic, it doesn't attract dust. It isn't attacked by insects or rodents.

Cork cells have an elastic memory, so cork doesn't deform permanently after an impact or compression.

Cork is also highly fire-resistant and hard to ignite.

Finally, it is a 100% natural, renewable and biodegradable material.

How is cork harvested?

The tree's first stripping doesn't take place before it is 25 years old.

The bark is harvested roughly every ten years, between late spring and summer. This pace lets the bark regenerate throughout the oak's life (about 170 years). Between each stripping, the cork oak is neither cut nor damaged. Cork is harvested only from the trunk, while the branches keep growing.

Cork is harvested by hand, using axes. The bark is then stored outdoors for six months, which lets the cells stabilise and the material lose its moisture. After that, the cork is boiled in water for an hour, which flattens the bark into planks. This step also increases its elasticity and removes all impurities. The cooking water contains no treatment additives, so it is a waste product with no risk of pollution.

How is cork fabric made?

Once harvested and treated, the cork oak bark is dried and then turned into several fine fibres. These are assembled by hand, then all the fibres are conditioned in a bath of natural essences. The material is then heated to a high temperature so the fibres bind thanks to suberin, a lipid component of cork that helps agglomeration. Cork sheets a few tenths of a millimetre thick are then laser-cut and bonded onto a textile backing thanks to the coagulating properties of suberin.

Worked like a fabric, cork is a vegan, flexible, light, natural material that can replace leather. It is tear-proof and can be cleaned with soapy water and a sponge. It feels velvety and soft, halfway between leather and suede.

What else is cork used for?

Cork is a zero-waste product: every part of the bark is reused and put to use during its processing.

70% of cork is used in the wine industry, especially for bottle stoppers. The rest is used in various fields such as interior decoration, leather goods and construction.

Ground and then compressed with resin, cork can for example be used as acoustic and thermal insulation.