Editing Cork (material) (section)

===Use in wine bottling===
[[File:Wine Corks.jpg|thumb|Cork [[Stopper (plug)|stoppers]] of various sizes for wine bottles]]
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.<ref>Prlewe, J. Wine From Grape to Glass. New York: Abbeville Press, 1999, p. 110.</ref>

Wine corks can be made of either a single piece of cork, or composed of particles, as in champagne corks; corks made of granular particles are called "agglomerated corks".<ref>{{cite web
 | title         = Guide for using wine corks
 | url           = http://www.brewerylane.com/corks.html
 | date          =
 | archive-url   = https://web.archive.org/web/20140113052418/http://www.brewerylane.com/corks.html
 | archive-date  = 2014-01-13
}}</ref>

Natural cork [[Closure (wine bottle)|closures]] are used for about 80% of the 20 billion bottles of [[wine]] produced each year. After a decline in use as wine-stoppers due to the increase in the use of synthetic alternatives, cork wine-stoppers are making a comeback and currently represent approximately 60% of wine-stoppers in 2016.<ref>{{Cite web
 | title         = International Organisation of Vine and Wine
 | url           = http://oiv.int
}}</ref>

[[File:Champagne uncorking photographed with a high speed air-gap flash.jpg|thumb|upright|left|High-speed [[air-gap flash]] image of a champagne bottle being uncorked]]
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. In a 2005 closure study, 45% of corks showed gas leakage during pressure testing both from the sides of the cork as well as through the cork body itself.<ref>{{cite web
 | last          = Gibson
 | first         = Richard
 | title         = variability in permeability of corks and closures
 | work          = [[American Society for Enology and Viticulture]]
 | publisher     = Scorpex Wine Services
 | date          = 2005-06-24
 | url           = http://www.scorpex.net/ASEVClosures2005RGibson.pdf
 | url-status    = dead
 | archive-url   = https://web.archive.org/web/20130512182445/http://www.scorpex.net/ASEVClosures2005RGibson.pdf
 | archive-date  = 2013-05-12
}}</ref>

[[File:ABS-5439.0-InternationalMerchandiseImportsAustralia-StandardInternationalTradeClassificationCustomsValue-633CorkManufactures-A1828854A.svg|thumb|right|Import value of cork manufactures to Australia since 1988 ([[Australian dollar|$]]million/month), showing a peak in 2002]]
Since the mid-1990s, a number of wine brands have switched to [[alternative wine closure]]s such as [[plastic]] stoppers, [[Screw cap (wine)|screw caps]], or other closures. During 1972 more than half of the Australian bottled wine went bad due to corking. A great deal of anger and suspicion was directed at Portuguese and Spanish cork suppliers who were suspected of deliberately supplying bad cork to non-[[European Economic Community|EEC]] wine makers to help prevent cheap imports. Cheaper wine makers developed the aluminium "Stelvin" cap with a polypropylene stopper wad. More expensive wines and  carbonated varieties continued to use cork, although much closer attention was paid to the quality. Even so, some high premium makers prefer the Stelvin as it is a guarantee that the wine will be good even after many decades of ageing. Some consumers may have conceptions about screw caps being representative of lower quality wines, due to their cheaper price; however, in Australia, for example, much of the non-sparkling wine production now uses these Stelvin caps as a cork alternative, although some have recently switched back to cork citing issues using screw caps.<ref>{{cite web
 | title         = Rusden Wines abandons screwcap for cork
 | url           = https://harpers.co.uk/news/fullstory.php/aid/11533/Rusden_Wines_abandons_screwcap_for_cork.html
 | publisher     = [[Harpers Wine & Spirit]]
 | website       = Harpers.co.uk
 | date          = 2012-07-26
 | access-date   = 2022-12-10
}}</ref>

[[File:Cork 1000x - SEM MUSE.tif|thumb|left|[[Scanning electron microscope|Scanning electron micrograph]] of cork ([[Museo delle Scienze]])]]
The alternatives to cork have both advantages and disadvantages. For example, screwtops are generally considered to offer a [[Cork taint|trichloroanisole]] (TCA) free seal, but they also reduce the oxygen transfer rate between the bottle and the atmosphere to almost zero, which can lead to a reduction in the quality of the wine.{{Citation needed|date=April 2016}} TCA is the main documented cause of [[cork taint]] in wine. However, some in the wine industry say natural cork stoppers are important because they allow oxygen to interact with wine for proper aging, and are best suited for wines purchased with the intent to age.<ref>{{cite web
 | title         = Cork or screw cap – which is best for your wine?
 | url           = http://www.corklink.com/index.php/cork-or-screw-cap-which-is-best-for-your-wine/
 | website       = Corklink.com
 | publisher     = CorkLink
 | date          = 2014-06-08
 | access-date   = 2022-12-10
}}</ref>

Stoppers which resemble natural cork very closely can be made by isolating the suberin component of the cork from the undesirable [[lignin]], mixing it with the same substance used for contact lenses and an adhesive, and molding it into a standardized product, free of TCA or other undesirable substances.<ref>{{cite web
 | title         = Diam Corks
 | url           = http://www.thewinesociety.com/growers-and-vintages-winemaking-diam-corks
 | url-status    = dead
 | archive-url   = https://web.archive.org/web/20141216121843/http://www.thewinesociety.com/growers-and-vintages-winemaking-diam-corks
 | archive-date  = 2014-12-16
}}, The Wine Society</ref>  Composite corks with real cork veneers are used in cheaper wines.<ref>{{cite news
 | last1         = Konohovs
 | first1        = Artjoms
 | title         = The True Cost of a Bottle of Cheap Wine (2012-03-14)
 | url           = http://kalw.org/post/true-cost-bottle-cheap-wine#stream/0
 | publisher     = [[KALW]]
 | date          = 2014-06-16
 | access-date   = 2022-12-10
 }}</ref> Celebrated Australian wine writer and critic [[James Halliday (wine)|James Halliday]] has written that since a cork placed inside the neck of a wine bottle is 350-year-old technology, it is logical to explore other more modern and precise methods of keeping wine safe.<ref>{{Cite web
 | last          = Halliday
 | first         = James
 | title         = Wine bottle closures
 | url           = https://www.winecompanion.com.au/resources/australian-wine-industry/wine-bottle-closures
 | website       = WineCompanion.com.au
 | access-date   = 2022-12-10
}}</ref>

The study "Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures," conducted by [[PricewaterhouseCoopers]] and commissioned by a major cork manufacturer, [[Corticeira Amorim|Amorim]], concluded that cork is the most environmentally responsible stopper, in a one-year [[Life cycle assessment|life cycle analysis]] comparison with plastic stoppers and aluminum screw caps.<ref>{{cite web
 |title        = Evaluation of the environmental impacts of Cork Stoppers versus Aluminium and Plastic Closures: Analysis of the life cycle of Cork, Aluminium and Plastic Wine Closures
 |publisher    = [[Corticeira Amorim]] (Amorim Cork Research)
 |work         = [[PwC]]/ECOBILAN
 |date         = October 2008
 |url          = http://www.amorimcork.com/media/cms_page_media/228/Amorim_LCA_Final_Report.pdf
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20161130111246/http://www.amorimcork.com/media/cms_page_media/228/Amorim_LCA_Final_Report.pdf
 |archive-date = 30 November 2016
 |access-date  = 3 April 2016
}}</ref><ref>{{Cite web
 | last          = Easton
 | first         = Sally
 | title         = Cork is the most sustainable form of closure, study finds
 | url           = http://www.decanter.com/wine-news/cork-is-the-most-sustainable-form-of-closure-study-finds-75623/
 | website       = Decanter
 | date          = 2008-12-08
 | access-date   = 2022-12-10
 | language      = en-US
}}</ref>