The cork harvest (descortiçamento) is an ancient and almost mystical process that allows the outer layers of the cork oak tree's bark to be removed without harming the tree itself. The origin of the cork harvest lies in the arid summers of the Mediterranean where the trade has been passed down from generation to generation for centuries. While the Mediterranean is the largest producer of cork bark harvested in the world, cork trees can grow and be successfully harvested in similar climates, such as the American Southwest. In China, there is a cousin to the cork oak tree (Quercus Suber), the Quercus Variabilis, otherwise known as the Chinese Cork Tree, whose bark is harvested in a similar fashion to the cork oak trees of the Mediterranean.
Cork bark harvesting occurs in the summer months (May-August), taking advantage of the high heat and dry weather of Mediterranean summers. The timing of the harvest is crucial as it allows the bark to regrow as the outer layers are harvested during the tree's growth period.
The process of harvesting the bark from the tree is a careful craft passed down through the generations. The hard work is undertaken with care and precision to avoid damaging the tree. A poorly carried out harvest can have severe consequences, preventing the bark from regrowing properly and even killing the tree in the worst cases. The harvest is carried out entirely by hand using a special axe designed to help protect the innermost layer of bark. The process of harvesting can be broken down into 6 steps.
Opening: This is the initial cut of the bark by the axe. The harvester must be careful not to make this vertical cut too deep.
Separating: The axe is then placed at the cut and carefully turned to separate the outer layer of bark from the inner layer.
Diving: Another horizontal cut is now made to delineate the plank further so that it can be removed. The larger the plank, the greater the harvest's value.
Extracting: The harvesters now carefully pull the cork plank off the tree, taking care not to damage either the tree or the large bark plank.
Removing: The harvester uses the axe to remove any remaining pieces of bark that did not come off with the plank to allow for a smooth regrowth of the bark.
Marking: The harvester spray paints the last digit of the year the harvest was conducted so the tree can be harvested on schedule.
When properly carried out, the harvest completely removes the outer and middle layers of cork bark while leaving the inner layer intact. If damage is done to the inner layer of the tree, a scar will remain for the tree's life and decrease the value of future harvests. The harvesters are also careful to harvest only from the trunk and thickest branches, leaving the bark around the branches' edges to promote the tree's continued growth and ensure that the tree will be productive for its entire 200+ year lifespan.
The cork oak tree is harvested for the first time when it is 25 years old. This virgin bark is a distinct product from later "reproduction cork," with the virgin harvest (desbóia) looking more like a traditional oak tree bark, rough, grooved, and twisted. This bark is ideal for decorative applications such as wall tiles, orchid mounting, and planters. The next time the bark is harvested is when the tree is 34 years old. This second harvest (secunderia) still has characteristics of the virgin harvest; however, the middle layer of the bark is much more defined than on the initial harvest. This harvest is still frequently used for decorative applications as well as to make granulated cork for a range of products.
By the third harvest, the cork bark is referred to as reproduction cork (amadia), meaning the middle layer of the bark is the thickest layer and is uniform around the tree. From this point forward, the bark will be harvested from the tree every 9 years for the rest of the tree’s impressive lifespan. This is the cork where wine corks and stoppers can be punched out of the bark before the remnants are used in other high-quality cork products such as fabric, flooring, and insulation.