Wine cork

Common alternative wine closures include screw caps and glass stoppers.

As late as the mid-17th century, French vintners did not use cork stoppers, using instead oil-soaked rags stuffed into the necks of bottles.

[3] Portugal is the largest producer of corks, at 52.5 percent, followed by Spain, Italy, and Algeria.

[2] Because of the cellular structure of cork, it is easily compressed upon insertion into a bottle and will expand to form a tight seal.

The interior diameter of the neck of glass bottles tends to be inconsistent, making this ability to seal through variable contraction and expansion an important attribute.

However, unavoidable natural flaws, channels, and cracks in the bark make the cork itself highly inconsistent.

[5] A study conducted by PricewaterhouseCoopers and commissioned by the major cork manufacturer Amorim concluded that cork is the most environmentally responsible stopper, in a one-year life cycle analysis comparison with plastic stoppers and aluminum screw caps.

The mushroom shape that occurs in the transition is a result of the bottom section's being composed of two stacked discs of pristine cork cemented to the upper portion, which is a conglomerate of ground cork and glue.

The aging of the wine post-disgorgement can to some degree be told by the cork, as, the longer it has been in the bottle, the less it returns to its original cylinder shape.