How is cork extracted?

Each trunk has to reach a circumference of 70 cm when measured at 1.5 metres from the ground. The first stripping, produces the so-called virgin cork which will be used for applications other than cork stoppers (flooring, insulation etc.), since its quality is far from that necessary to manufacture stoppers. 

Nine years later, the second harvest produces material with a regular structure, less hard, but still not suitable for cork stoppers – this is known as secondary cork.

It’s from the third and subsequent harvests that the cork with the best properties is obtained, suitable for the production of quality corks, since its structure is regular and smooth outside and inside. This is the called the reproduction cork. From then on, the cork oak will supply good quality cork every nine years for around a century and a half, producing, on average, 15 to 16 bark strippings throughout its life.

The stripping of the cork oak is an ancient process that can only (and should only) be done by specialists, the debarkers, since much manual skill and experience is required in order not to harm the tree. The stripping process consists of five steps:

1. Opening, being performed a vertical cut in the cork, choosing the deepest crack in the cork bark. At the same time, the edge of the axe is twisted so as to separate the outer from the inner bark. The degree of difficulty of extraction can be gauged from the ‘feel’ of the axe. When the edge of the axe is applied to the strip, a hollow sound of tearing is heard if the cork is going to come off easily. If it is going to be difficult, the axe gives off a short, firm, dry sound.

2. Separating. The plank is then prised off the tree, by inserting the edge of the axe between the strip and the inner bark. The axe is twisted between the trunk and the cork strip to be extracted.

3. Dividing. A horizontal cut defines the size of the cork plank to be removed and what is to remain on the tree. During dividing, the inner bark is frequently marked and these mutilations can sometimes alter the geometry of the trunk.

4. Extracting. The plank is removed from the tree with care so that it does not split. The larger the planks extracted, the greater their commercial value. The removal of entire planks depends on the skill of the workers. After the first plank has been stripped, the operation is repeated over the whole trunk.

5. Removing. After the stripping of the planks, some fragments of cork remain attached at the base of the trunk. To remove any parasites in these “wedges”, the debarker gives them a few taps with his axe.
Finally, the tree is marked, using the last number of the year in which the extraction took place.
After the harvest, the cork planks are stacked in piles either in the forest, remaining exposed to the natural elements. All these piles are constructed taking into account strict specific rules (ICCSMP), so as to allow the cork to stabilize. The piles should be stacked on materials that do not contaminate the cork and prevent contact with soil. Wood, for example, is expressly prohibited because it can transmit fungi. This is called the seazoning period than last at least for 6 months.

More of Cork as ecological material

Our company bases its philosophy of making business in the respect for nature and potentiating its protection. Our products are harvested with traditional methods, allowing to develop the local economies. The cork oak survives without the use of chemical herbicides, fertilizers. The tree doesn’t need irrigation and moreover, it’s renews itself after harvesting it’s cork, which his performed in in intervals of 9 years between each harvest., being that the tree can be first time harvested at 25 years of age, and can live around 200 years.

Cork oak bark grows in around of 1.5 mm each year retaining huge amount of CO2 from the atmosphere during his growth. In fact a stripped cork oak absorbs, on average, five times more CO2. Less than 1,5 hectares of Montado (Forest of cork oak trees) are necessary to mitigate the annual carbon dioxide emissions of an average vehicle. The manufactured cork products will continue to retain carbon (half weight of a natural stopper when dry and approximately 1,7g of carbon per natural stopper or 6,2g of CO2).

Systems such as the Forest Stewardship Council (FSC) certify forest management systems, like the Montado, by the fulfilment of environmental, social and economic character criteria. Currently, there is in Portugal (country  where CORKMARKET material are produced) approximately 15 thousand hectares of FSC certified Montado and forestry associations have officially committed to reaching 150 thousand hectares of certified Montado in the near future.

In what respects production of cork products, from a Study of PWC the production and usage of each plastic stopper releases 10 times more CO2 than a cork stopper and presented CO2 emissions for the aluminum stopper 26 times superior to that of cork. The same it happens it construction materials made from cork.

Besides this, part of our products are built from recyclable materials. Cork as product can be easily 100 % recycled or reused, giving origin to new cork products like footwear or other products.
Due to it’s characteristics cork products still continue their job in environment protection. Cork is a natural product that used as construction material, reduces the energy consumption, as it’s thermal efficient.

So when CORKMARKET products arrive to you, you should fell proud you took a great part in the environment protection. So we say, nature meets technology, and technology respects nature.

cork harvest

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If you’re looking for a limited series or mass production we will make a perfect fit, using our technology and a range of coatings solutions to improve your cork product life time cycle. CORKMARKET also provides customization with different printing or inscription solutions. From concept to deliver, trough production and packaging we provide our clients with the most suitable solutions.