Factbox: Key facts about cork and its use

Cork stoppers for champagne are seen at the Vinitaly wine expo in Verona April 3, 2009.

(Reuters) - Following are some key facts about cork and its main applications, from bottle stoppers to aerospace industry.

* Cork is made from the bark of the cork oak (Quercus suber) -- the predominant tree species in Portugal. Portugal accounts for just over half of the world's cork output, producing 157,000 tonnes annually. There are also plantations in France, Spain, Italy, Algeria, Morocco, and Tunisia.

* Over 100,000 people depend on cork growing and processing in these countries.

* The bark is harvested for the first time when the tree is 25 years old. Then it is removed every 9-12 years without ever damaging the tree, which lives around 200 years. Cork obtains the qualities needed for the production of wine bottle stoppers -- its main application -- only after the third harvesting.

* The tree's acorns are used to feed pigs that make some of the best cured ham Spain and Portugal are famous for.

* Thanks to the cork's cell-like structure, the material is elastic, resilient and highly impermeable.

* The ancient Greeks and Romans used cork in combination with natural resins to stopper wine and oil amphorae. Now, some 70 percent of all cork produced is used to make wine bottle stoppers. Portugal alone makes 40 million stoppers per day.

* Cork stoppers sometimes taint wine with trichloroanisole (TCA), which gives the wine the undesirable "wet dog" odor. Various studies put the share of TCA-tainted wine at 1 to 7 percent. Major cork producers have developed methods to remove most of TCA from corks as they try to fend off the advance of alternative closures like metal screwcaps.

OTHER APPLICATIONS

* Entire pieces of cork are also used in footwear, furniture, interior decoration as well as older lifebuoys. The baseball ball has a round cushioned cork center called a "pill."

* Ground-up cork is "baked" and compressed to make floor and wall tiles, good for acoustic isolation. Granulated cork is added to concrete for thermal insulation and reduced weight.

* Shredded cork is used in ablative thermal protection coating on booster rockets, including the Space Shuttle's external tank, which is jettisoned as the ship leaves the Earth's atmosphere.

(Reporting by Andrei Khalip, editing by Paul Casciato)