Cork (material)

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Image:Cork stopper.jpg Image:ChampagneCorksLarge.jpg Image:Champagne cork.jpg Template:Otheruses4 Cork material is a subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree, Quercus suber, with Portugal producing most cork worldwide.

Cork's elasticity combined with its near-impermeability makes it suitable as a material for bottle stoppers, especially for wine bottles. Cork stoppers represent about 60% of all cork based production. Cork's low density makes it a suitable material for fishing floats and buoys. Sheets of cork, often the byproduct of more lucrative stopper production, are used to make floor tiles and bulletin boards.

The cork industry is generally regarded as environmentally friendly. The sustainability of its production and the easy recycling of cork's products and by-products are two of its most distinctive aspects. One of the leading companies in the cork industry is Amorim Group, from Portugal.

Cork demand has increased due to a larger proportion of wine being sealed with cork rather than being sold in bulk. Since a tree's bark can only be harvested once a decade or so, supply is highly inelastic. Top quality corks are quite expensive, so cheaper brands have switched to lower quality cork, synthetic plastic stoppers, screwcaps, or other closures. The synthetic stoppers do not dry out and shrink so the bottles do not have to be on their sides to prevent the wine from oxidizing. However, on the down side, both synthetic stoppers and screwcaps require different winemaking methods to some extent, as sulfur dioxide (SO₂) levels need to be different, and there may be different wine faults due to oxidation or reduction.

Cork contamination with harmless but foul-smelling trichloroanisole (TCA) is one of the primary causes of cork taint in wine. Cork related trichloroanisole has been almost eliminated by means of new patented and more reliable production and testing methods, such as changes in the bleaching process, and high quality control standards.

Recently cork has also been used in rocket technology due to its fire resistance. It can also be used as bricks for the outer wall of a house (this was done in Portugal's pavilion at Expo 2000).

1 Environment
2 Trivia
3 See also
4 Sources

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Environment

Oak woodlands in Spain and Portugal, known as dehesas or montados, have been used to produce cork and graze livestock for hundreds of years, making them a haven for wild birds.

Some 42 species of bird depend on the cork-producing woodlands, including the endangered Spanish Imperial Eagle, of which only 130 pairs remain, and other rare species including the Black Stork and Eurasian Black Vulture. In Spain, about 100 pairs of the eagles depend on the dehesas for survival.

Other smaller birds, including European Robins, Chaffinches and Song Thrushes, migrate to the dehesas from northern Europe, along with blackcaps from the UK. The dehesas are also home to a rich variety of butterflies and plants in spring and summer. They provide more than 80% of the world's cork, of which two-thirds is used for wine and champagne stoppers.

The corks are produced from the bark of cork oaks, which can live for centuries. They are stripped every nine years, giving the tree time to regenerate its bark and so produce more cork.

One particular tree, cited in the Guinness Book of Records, known as the "Whistler Tree" because of the many singing birds attracted to it, is said to be 212 years old. This tree alone had produced up to one million corks by 2000.

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Trivia

The Cork Oak is unrelated to the "cork trees" (Phellodendron), which have corky bark but are not used for cork production.
As late as the mid 1600s, French wine makers did not use cork stoppers. Instead, they used oil-soaked rags stuffed into the necks of bottles.

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