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Cork Harvesting

The process of cork harvesting is relatively simple, it is the process of ‘demasking’. This consists of stripping the cork-oak of its natural cork bark (male cork) so stimulating the production of a second cork layer, the female cork or reproduction cork. At the time of removal of the male cork the trees must have a circumference of 70 to 80 centimetres or, in the most favourable forestry areas, an age of 25 years.

"With a simple small, curved axe, Portuguese workers cut out with remarkable speed a perfect delineation, difficult to execute using other more delicate or complicated to handle tools."
(Natividade, 1956)

Cork is removed every 9 years in Portugal (10 or 12 in France), always in the summer, the most convenient time for the harvest. During the most intense growth stages, which occur usually between June and July, the growth of cells is quick and layers formed are thin and fragile. This property is taken advantage of to tear apart the recently formed cork cell membranes. According to the Portuguese this is the moment where the cork-oak ‘begins to sweat’. The layer that remains exposed retains the capacity for regeneration of a new cork layer. The procedure must be undertaken with care: if there are lesions the tree may suffer from infections.

The first removal is therefore undertaken, and the male cork is removed which, being hard, inelastic, irregular and dense is unusable in the production of stoppers. It is only at the third removal, when the tree is over 40 years old, that cork of a high quality will be obtained.
Next, the sheets removed are dried then boiled in loads. When out of the water they are softened under the mallet, beaten by machine and classified according to their value. The thickness, elasticity, fineness and colour all count towards the value.

In producer countries, cork-oak is protected by numerous laws which ensure its well-being and production. The most important ones ban the removal of cork from young trees and from the oldest trees, and forbid removal of cork from a tree at intervals of less than nine years.