Issue 47 JUNE - Flipbook - Page 87
Barnacork
The uses of cork
Cork, thanks to its multiple properties, is a very versatile product, which is why it is found in a multitude
of applications in very different sectors including the Nina and Co. project. Spanish based company
Barnacork explain the development and uses.
What is cork?
Cork is the bark of the cork oak (Quercus suber), which
protects it from the extreme conditions of the Mediterranean climate, such as drought, high summer temperatures, and fires.
After this first extraction, cork can be extracted every
nine years, depending on the quality of the season and
the climate zone.
How is cork made?
There are basically two different processes for treating
cork. The first is used to create cork stoppers for bottles.
In this process, the cork is boiled at 100 degrees Celsius
for approximately one hour, then left to cure for a year.
Once cured, the cork is boiled a second time, cut into
strips, and drilled to create the corks.
It is made up of closed cells whose interior is filled with a
gas similar to air. This gas constitutes almost 90% of cork,
hence its extremely light weight and compressibility. The
walls of these cells, which are like tiny airtight compartments, are composed primarily of suberin and cerin,
substances that make it highly fireproof, very flexible, and
practically rot-proof.
In the second process, the lower-quality cork and the
remnants of the good cork sheets are cleaned, crushed,
bonded, and pressed to obtain a cork agglomerate in a variety of forms: granules, sheets, rolls, bars, or other geometric shapes. Its uses are varied, from lower-quality
bottle corks to floor or ceiling tiles, as insulation, as a sealing gasket, or in panels for acoustics, decorations, or notes.
Cork is, therefore, an extraordinary material with unique
properties. It is a completely natural, renewable, and
biodegradable product.
Its production does not cause any pollution or harm to
the ecosystem from which it is extracted, since it is obtained by stripping the bark of the cork oak, without cutting down any trees, and this "harvest" is carried out every
9 to 12 years.
The cork production process follows an integrated
and sustainable system in which every part is utilized.
Thinning and pruning provide valuable firewood; the first
harvest yields granules for insulation; the scraps left over
from cork production are used to make agglomerates; and
the final waste from the entire production process is used
as fuel for the boilers and kilns used to produce the
finished product.
How is cork obtained?
Cork extraction is a very environmentally friendly process,
with very low impact and obtained from renewable
resources since it doesn't even require felling trees.
Extracting cork from the cork oak is known as "cork
harvesting." This harvesting takes place primarily during
the month of July, the month in which the cork can be
separated from the tree without damaging it. During this
time, workers called "corcheros" or "peladores" (cork peelers) extract the bark from the cork oak by cutting with
an axe and joining the vertical cracks in the cork, thus
removing what is called "the cork peel."
Properties and applications of cork
Few materials simultaneously exhibit so many useful
characteristics. To name just a few of its properties, cork
is impermeable, odorless, resistant to chemicals and
unaffected by liquids, virtually rot-proof and highly resistant to insect attack, compressible and elastic, with
extraordinary dimensional recovery, low thermal conductivity, excellent acoustic and vibration insulation, very
lightweight, and highly mechanically resilient.
Cork can be extracted for the first time when the tree is
approximately 25 years old, but this figure depends greatly
on the climatic conditions during its growth stage, since
the parameter to be measured is when the tree has a
"chest height circumference" (CAH) of 70 cm at a height
of 1.30 m.
Given its extraordinary characteristics, it's no surprise that
cork has multiple applications. Some of its uses are very
old. In many cases, synthetic materials have partially replaced it. But, in reality, in most of its uses, it is unrivaled.
Among other applications, cork is used in shipbuilding,
where it is used for everything from thermal insulation
and anti-vibration to non-slip flooring, lifebelts and
armour, buoys, and so on. In machinery manufacturing,
This first cork is called bornizo, and is only suitable for
making decorative and insulating elements.
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Conservation & Heritage Journal
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