A cork oak tree is harvested or stripped for the first time when it is twenty five years old, and thereafter once every nine years. It’s sold for many different uses from floor tiles to fishing floats, but the greatest revenue comes from the billions of stoppers we use each year to close our wine and champagne bottles. it’s because of the high value of cork bark that this ancient landscape, with its rural culture and its wildlife, have been protected until today.
Cork’s structural composition is remarkable. A 1 inch cube contains roughly 200 million fourteen-sided cells filled with air. cork is four times lighter than water, yet highly elastic, capable of snapping back to its original shape after withstanding 14,000 pounds of pressure per cubic inch. Cork is impervious to air, almost impermeable by water, difficult to burn, resistant to temperature changes and vibration, does not rot, and has the ability to mild itself to the contour of the container it is put into, such as the neck of a wine bottle.
What an extraordinary tree! Cork oaks are the only trees in the world from which you could strip an entire piece of bark like this without killing it. Every tree this size yields sufficient bark to produce 4,000 corks, and this harvest provides employment for at least 60,000 Portuguese workers.
the stripping itself is gruelling work. Using special wedge-shape axes, workers peel 4-foot planks from the bark during the intense summer heat when the tree’s sap is circulating, making it possible to pry off the bark. Once the bark is stripped off, it is left outdoors to season and dry for up to a year.