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Phase
2 : The cork preparation |
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| The delicate operation
of stripping
is performed in summer by the 'cork strippers' using an axe with a bevel
edge to ease the separation of raw plates. After making a circular notch
from the cork tree crown, the bark is cut along chosen vertical cracks to
get tubes or
plates, depending on the tree circumference. The cork is then carefully
stripped without damaging the reproductive base called
mother. |
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The desiccation
process.
As with wood, the tubes are
exposed to season in piles for 12 to 18 months to allow the cork to refine
by oxidation. The seasoning eliminates part of the hydro- soluble tannins and
the mineral salt. The cork boards are then pre-sorted. |
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The boiling
process
In the factory, the cork undertakes its initial
'in-house' treatment with a 60 minutes process in boiling water. This
primary cleaning completes the elimination of hydro-soluble particles,
flattens the cork and enhances its suppleness and homogeneity. The
material expands 20 % during this process. The cork is afterwards ripened
for 3 to 4 weeks in warehouses at a constant temperature, sheltered from
light. It acquires optimum characteristics enabling punching. |
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Marking-off, facing and
cork sorting.
Facing is a skilled task performed by workers who
evaluate each board and put
aside defective material. They check for homogeneity, colour and
cleanliness of the material. They mark off, re-cut and straighten up the
boards. These are then professionally sorted into batches of 7 thickness
categories, and 6 classes of qualities. |
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During the complete
process, 50 % of the initial material is put aside for by-
products, 20 % during the desiccation
process, and 30 % during the marking-up and facing operation.
This severe qualitative selection applied to a natural product
corresponds to the initial inspection of raw material before further
production. The waste is used for the manufacturing of flexible
agglomerated insulation. |
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