Due to its versatility cork has had been administered a variety of uses of which the most prominent is its use as a cork stopper. This function is definitely a great advantage in a nation like Portugal which is famous for its vineyards and supreme quality wines and therefore the abundance of cork production and wines greatly complement each other. In order to realize why corks can act as perfect stoppers for bottles of wine, one must necessarily examine the chemical properties of the cork.
Though the cork cell was first researched extensively by Robert Hooke, an Englishman in the 18th century, cork has been used widely for other purposes since antiquity. But with the discovery of the use of cork as stoppers for wine bottles, the demand has increased by leaps and bounds and Portugal today constitutes 50% of the total cork production worldwide. Cork is the extracted bark of the cork oak tree and is flexible and elastic, light and compressible and is able to withhold the entry or exit of gases and liquids. It is resistant to combustion and also acts as a magnificent acoustic and thermal insulator. This is because cork is comprised of a substance called suberin which is made up of organic acids due to the presence of which gases and liquids are unable to permeate into the cork. This also makes it airtight and sealed which should be the primary purpose of the cork stopper in wine bottles to preserve the freshness, maturity and quality of the product. Cork stoppers have emerged to be the most important application of cork in Portugal today and there are seven major types of cork stoppers manufactured in the country. These include capsulated cork stoppers, agglomerated cork stoppers, natural cork stoppers, technical cork stoppers, colmated natural cork stoppers, champagne and sparkling wine cork stoppers. Usually cork stoppers are expected to be about 6mm above the bottle neck and should not be compressed more than 33% in diameter.