Cork (material)

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Many corks

A cork stopper for a wine bottle

Champagne corks

Varnished cork tiles can be used for flooring, as a substitute for linoleum or tiles.

Simple cork

This article is about the commercially used material. For the city in Ireland, see Cork (city). For other uses, see Cork.

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 consists mostly of suberin.

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, as well as handles for fishing rods (as an alternative to neoprene). Cork is also used in the manufacture of musical instruments, particularly woodwind instruments, where it is used to fasten together different segments of the instrument and make the seams airtight. Sheets of cork, often the by-product 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 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.^{[citation needed]}

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).

[edit] Trivia

In his 1664 book Micrographia, English scientist Robert Hooke coined the term "cell" while observing the intricacies of a piece of cork through a microscope because his observations of dead empty plant cells reminded him of monks' living quarters which were called "cellula".^{[citation needed]}
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.
The first filtered cigarettes used cork to filter the smoke as it was inhaled^{[citation needed]}.