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The Many Uses Of Cork
Cork is a light resilient material that is found in small amounts in the outer bark of most woody-stemmed plants.
The only commercially significant source of cork is the bark of the cork oak (Quercus sufoer). The cork oak must be about 20 years old before its bark is removed for the first time. Thereafter it is harvested about once every 10 years.
There are two kinds of raw cork: One is known as corkwood. This is the material used to make wine bottle stoppers, floats, and life preservers. The second kind of raw cork is called grinding cork. It is ground up and then baked, some of it with binder materials. This is made into pipe covering, shoe fillers, automobile gaskets, and liners such as you find in the crown of bottle covers.
Cork is much lighter than water. The reason it floats is that water does not easily penetrate the walls of the cells, which are filled with air. This prevents the cork from becoming water-logged and sinking.
Cork is nearly tasteless and odorless, resists deterioration, and is more than 50 percent air by volume. Which makes it ideal for wine bottle corks.
Where does cork come from?
Cork is the outer bark of the cork oak tree. The cork oak is native to the Mediterranean region. Two-thirds of the world's cork supply comes from Spain and Portugal, where the cork oak is cultivated extensively.
The cork oak grows from 20 to 40 feet tall and often measures as much as four feet in diameter. The bark of this tree is usually first stripped when the tree is about 20 years old. This doesn't injure or kill the tree; instead, the stripping actually benefits it.
About nine years later, another stripping is taken. The cork obtained from these first two strippings is coarse and rough. Later strippings, which are made about nine years apart for about a hundred years, give cork of a finer quality.
The cork is slit with a specially designed ax or curved saw and pried and peeled loose with the aid of levers and wedges.
After stripping, the cork is stacked for several weeks to season, and then boiled to soften it and to remove the tannic acid.
After boiling, the cork lies in pliable flat sheets. The coarse outer section of the bark is scraped off and the remaining cork is pressed and dried into finished cork and then packed for shipping all over the world.
Uses For Cork
In the United States about half the cork used is made into corkboard, which is used for insulation. Another 25 percent is used as a lining for bottle caps. Cork is also used for bottle stoppers, vibration pads, gaskets, oil retainers, polishing wheels, floats for rafts and nets, baseball cores and cork flooring. Cork flooring is excellent for insulating floors. It's both comfortable to walk on and it keeps the cold out.
Cork scrap cuttings are used to insulate refrigerators, to pack fruit for transportation, and to make linoleum.
One of the greatest uses of cork today is for soundproofing rooms, and for insulating warehouses, freezer rooms, and refrigerators.
Often pigs are kept under the trees to root for the acorns which fall in autumn. When the cork is stripped it is boiled and then pressed to make the material we use in many ways, from medicine bottle stoppers to lifebelts.
More, Tell Me Why, Arkady Keokum, Hamlyn. 1967. Page 74.
365 Things To Know, The Hamlyn Publishing Group, 1968. Page 226.
Merit Students Encyclopedia, Volume 5, P.F. Collier Inc, 1979. Page 267.