How cork is made
An illustrated guide to the cork production process
It all starts in
the forest. Cork oaks are harvested every nine years, once they
reach maturity. It doesn't harm the tree, and the cork bark regrows. Most
cork forests are in Portugal and Spain.
The year of
harvest is marked on the trunk, so each tree isn't harvested at the
wrong time. Cork is a great insulating material, and gives these
oaks a chance to survive the forest fires that occasionally happen
in the hot Mediterranean summers.
Here's a close-up
of a tree that was harvested the year previously.
cork planks are stored before processing. Good cork companies will
store them on concrete rather than bare earth, lowering the risk of
This is a
close-up of a piece of bark. It's quite thin, and won't be used to
produce high-quality natural cork. But now there are also technical
corks, made up of small pieces of cork fused together, which means
that more of the cork bark is suitable for producing wine bottle
processing, the cork planks are put on pallets. Then they are ready
for the first stage in the cork production process: boiling. The
following pictures were taken at Amorim's facility in Coruche, ion
the south of Portugal.
planks are boiled to soften them, and also to clean them. In the bad
old days these would be boiled in murky pits without the water being
changed very often. Now, to avoid cross-contamination, the water is
cleaned, filtered and replenished regularly, with volatiles being
removed on a continuous basis.
This batch is
just going in.
The boiled planks
are flatter and easier to work with
This is a
nice-looking piece of cork.
Next the planks
are graded and cut into workable pieces.
Some will be used
for punching natural corks out of; others will be used to make
technical corks. The pictures below were all taken at Amorim's
factory in the north of Portugal, south of Porto.
These workers are
hand-punching corks from strips of bark: these will be high-end
corks. Others are machine punched.
It is a skilled
process: make the wrong decisions and the corks aren't good enough,
or cork is wasted.
after the corks have been punched. This remaining cork can be ground up to make granules
that can then be
glued together to make agglomerate cork.
The corks are
optically sorted: blasts of air are used to send the corks into the
right grade bins.
Then the corks
are sorted by eye.
Great care is
taken sorting the top grade corks.
These corks will
be really expensive: over a Euro each.
On to part two:
making technical corks