The Harvesting of Cork
Cork, also known as QUERCUS SUBER, botanically, is the bark
of an oak tree. Grown in areas bordering the Mediterranean
sea, it is an evergreen which grows in commercial stands.
Portugal supplies approximately 50% , and Spain supplies about
25%. France, Morocco, Algeria, Italy and Tunisia make up the
balance. Cork was used for fishing boats in ancient Egypt
as early as 2,500 BC. In 400 BC, soles of shoes and stoppers
for containers were made from cork. Conqueror Alexander the
Great, was a famous user of cork. According to reports, a
cork piece once in a turbulent river once saved him from drowning.
Cork is the only tree that can regenerate itself after each
harvest, and with increased concern of the environment, it
is a wonderful resource. The cork is not harvested until the
tree is approximately 20 years old. Cork is then stripped
off 2/3 of the tree. "Virgin Bark" is the very first bark
that is taken from a tree. It has a grayish color to it and
a very irregular surface. This is suitable for grinding into
various minute sizes indeal for composition cork and cork
insulation. This "virgin bark" has also become very popular
in the use of the manufacturing of decorative items. Cork
trees have a protective thin layer of inner bark that gives
it a unique ability to survive and regenerate itself after
the debarking process. The inner bark must not be damaged,
therefore stripping the bark requires great skill. For the
stripping process, a specially designed hatchet is used.
Until the cork oak is approximately 150 years old, it will
have subsequent strippings of the tree every nine years, at
which time the tree is then replaced with a much younger one.
After the stripping of the "virgin bark", all stripping after
that is called "refugo bark". Refugo bark looks different
entirely because it is brown in color and has a much smoother
surface. Mostly for grinding purposes is what the first crop
of refugo bark is used for. After that, the subsequent strippings
have better quality of cork that is made up of fewer and more
closed pores (grains). The production of cork stoppers and
other items make up the majority of these harvests.
The bark remains in the forest for several days to dry or
in some cases, to be inspected by potential buyers, after
the stripping process is completed. Purchasing cork bark is
not an easy process because the quality not only varies from
different forests, as well as different trees, but the same
tree can produce different degrees of quality corks depending
on its sunlight exposure.
Once the refugo bark is in the factory area, the bark is boiled
to make the removal of the outer layer, easier, and the make
the bark more elastic, in order to get it flattened out, should
it be sold later on. Then the bark is sorted by the thickness,
and then in turn sorted into the different qualities to help
in the determination process of the sale price and/or suitable
manufacturing use.
Cork with its unique qualities as well as being a natural
product, is really unmatched by any other natural material
found. Just one cubic inch of cork has no less than 200 million
enclosed air cell, each that measure 1/1000" in diameter.
Each cell is 14 sided, which means it virtually eliminates
empty spaces between cells.
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