Cork oaks develop a thick bark as a protection against Mediterranean threats such as heat and fire. Cork is the bark of the cork oak tree, a typical tree in the Alentejo.
Portugal is the world’s first producer of cork, which apart from bottle tops it is used in a wide range of insulation products as well as in the fashion, shoe and cosmetic industry.
Debarking is done by hand, between the months of May and September, corresponding to peak in growth.
The trees should be at least 20 to 30 years old before they are first stripped, and this primary cork is very porous, crooked and irregular so it is mainly used in agglomerates due to its elastic and insulating properties but is of poor quality for bottle tops. This second cut is also not very good quality so it is also send to macerating to make agglomerates.
The Interval between cuts is 9 years, and the trees can be debarked about 10 to 15 times in their lifetime. The tree can live on average about 250 years, and 400 if it is not stripped.
After the cork is removed, the trunk acquires a cinnamon colour gradually changing to brown, and then is marked, usually in white, with the number of the year it was cut. So if you see 8 painted on a tree, it means that has been stripped in 2008 and will be again in 2017. The planks of cork are pilled to dry for about 6 months before processing.
Manufacturing first involves boiling the cork planks in water for about 1 hour in order to disinfect and remove tannins, making it softer and more flexible.
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