Wine cork

thumb|upright|A French wine cork A '''wine cork''' is a stopper used to seal a wine bottle. They are typically made from cork (bark of the cork oak), though synthetic materials such as rubber or plastic can be used.<ref>{{cite web |last=Priberam Informática |title=Dicionário Priberam da Língua Portuguesa |trans-title=Priberam Dictionary of the Portuguese Language |url=https://dicionario.priberam.org/rolha |access-date=29 November 2024 |website=Dicionário Priberam da Língua Portuguesa |language=pt-br }}</ref> Common alternative wine closures include screw caps and glass stoppers. 68 percent of all cork is produced for wine bottle stoppers.<ref name=":0">{{cite book |url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf |title=Manual Técnico Rolhas |trans-title=Technical Manual of Wine Corks |last=Dias |first=Jacinto |publisher=APCOR - Associação Portuguesa da Cortiça |year=2015 |location=Santa Maria de Lamas, Portugal |page=7 |language=pt }}</ref>

Corks are manufactured for wines and sparkling wines; the latter are bottled under pressure, forcing the corks to take on a mushroom shape. They are fastened with a wire cage known as a muselet<ref name=":022">{{cite web |last=Infopédia – Dicionário da Língua Portuguesa |title=gaiola |trans-title=wire cage |url=https://www.infopedia.pt/dicionarios/lingua-portuguesa/gaiola |website=Infopédia Dicionário da Língua Portuguesa |access-date=14 August 2023 |language=pt }}</ref> of wire, and this twisted wire structure is usually accompanied by a metal cap on which the brand logo is normally stamped<ref name=":6">{{cite book |url=https://www.amazon.fr/R%C3%A9pertoire-plaques-muselets-du-champagne/dp/2956877518 |title=Répertoire des plaques de muselets du champagne: nouveautés 2017, 2018, 2019, et 2020 |trans-title=Catalogue of Champagne Muselet Caps: New Issues 2017, 2018, 2019, and 2020 |last=Lambert |first=Laurent |publisher=Lambert collections |year=2021 |location=Bassuet |page=198 |isbn=978-2956877516 |language=fr }}</ref>, and in the case of champagne bottles it is often covered with metallic foil.<ref name=":1">{{cite book |url=https://gallica.bnf.fr/ark:/12148/bpt6k63658190 |title=Au pays du Champagne : le vignoble, le vin |trans-title=In the Land of Champagne: The Vineyard and the Wine |last=Moreau-Bérillon |first=C. |publisher=Librairie L. Michaud |year=1925 |location=Reims, France |page=446 |language=fr }}</ref>

==History== [[File:Vinova synthetic wine closure.jpg|225px|thumb|Synthetic corks]] Cork has been used to seal bottles and vessels for 5 millennia, Ancient Egypt, Greece, and Rome, all used cork stopper.<ref>{{Cite web |date=2025-10-22 |title=The Origin of the Cork: Unveiling the Mystery Behind the Invention - ElevatingKitchen |url=https://elevatingkitchen.com/who-invented-the-cork/ |access-date=2026-01-04 |language=en-US}}</ref><ref>{{Cite web |last=TomLovesWine |date=2018-12-31 |title=Corked Wine: History Of The Cork - SecondBottle Presents Corked Wine! |url=https://www.secondbottle.co/corked-wine-history-cork/ |access-date=2026-01-04 |website=SecondBottle |language=en-US}}</ref>

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>

In the 19th century, in the United Kingdom, the first machines for manufacturing cork wine corks appeared.<ref name=":2">{{cite book |url=https://epdrgrandola.pt/wp/wp-content/uploads/2019/tic/texto-de-trabalho-turismo-corti%C3%A7a-trabalhado.pdf |title=A cortiça |trans-title=Cork |last=Dias |first=Jacinto |publisher=Escola Profissional Desenvolvimento Rural de Grândola |year=2018 |location=Grândola, Portugal |page=5 |language=pt }}</ref>

In the early 21st century, the problem of "cork taint", caused by the release of trichloroanisole resulting from the interaction between fungi present in the environment and compounds used in the manufacture of wine corks,<ref name=":3">{{cite web |last=Santos |first=Pedro Emanuel |title=Cortiça que vale ouro |trans-title=Cork that is worth gold |url=https://www.noticiasmagazine.pt/2020/cortica-que-vale-ouro/historias/249276/ |website=Notícias Magazine |date=22 May 2020 |access-date=29 November 2024 |language=pt }}</ref> became increasingly prevalent, leading many producers to opt for synthetic alternatives. Screw caps became especially prominent in Australia and New Zealand by 2010. Most cork was sourced from around the Mediterranean Basin, far from the Oceanian countries.<ref name="Atl">{{cite web|author=John Gifford |url=https://www.theatlantic.com/technology/archive/2016/02/wine-cork-comeback/470961/ |title=How Millennials (Almost) Killed the Wine Cork |publisher=The Atlantic |date=2016-02-25 |access-date=2020-02-27}}</ref>

Following issues with cork taint, the cork industry invested in new techniques and equipment, reducing TCA chemicals in wine by 95 percent. Cork producers began promoting the cork's environmental and economic benefits.<ref name="Atl"/>

==Production== thumb|upright|Manual corking machine, manufactured c. 1870 Like other cork products, natural wine corks are derived from the bark of cork oak trees. The bark is carefully peeled away and cut into sheets before processing. The oak trees are not cut down, and only about half of its bark is removed at any time. Cork oaks are first harvested at 25 years old, and take place every 9 years. After the third harvest, the bark is of sufficient quality for producing wine corks.<ref name="apcor2">{{cite web|author=João Santos Pereira|author2=Miguel Nuno Bugalho|author3=Maria da Conceição Caldeira|title=From the Cork Oak to cork|work=APCOR|url=https://www.apcor.pt/wp-content/uploads/2015/09/From-the-Cork-Oak-to-Cork-a-sustainable-system.pdf|date=2008|access-date=February 28, 2020|archive-date=October 13, 2023|archive-url=https://web.archive.org/web/20231013011019/https://www.apcor.pt/wp-content/uploads/2015/09/From-the-Cork-Oak-to-Cork-a-sustainable-system.pdf|url-status=dead}}</ref>

Portugal is the largest producer of corks, at 52.5 percent, followed by Spain, Italy, and Algeria. The majority of Portugal's production is in the region of Alentejo, at 72 percent of national production.<ref name="apcor2"/> 68 percent of all cork is produced for wine bottle stoppers.<ref name="Atl"/><ref name="apcor2"/>

===Products=== Corks can be made in several ways:<ref name="apcor">{{cite web|title=Corks|work=APCOR|url=https://www.apcor.pt/produtos/rolhas/|access-date=February 28, 2020|archive-date=September 21, 2023|archive-url=https://web.archive.org/web/20230921112518/https://www.apcor.pt/produtos/rolhas/|url-status=dead}}</ref>

* Natural cork stoppers are made from a single piece of bark, and have the best flexibility, keeping the seal strong for aging wine for over 5 years. * Colmated corks are made from a single piece of bark, but have pores filled with glue and cork dust. They are easier to remove from a bottle, and are good for medium aging. * Multi-piece corks have two or more pieces glued together. They are denser than single-piece corks, and are not good for prolonged aging. * Agglomerated corks are made of cork dust and glue, and are dense, inexpensive, and not good for sealing wine for over a year. * Technical corks are agglomerated corks with single pieces of cork on either end.

== Parameters for assessing the quality of wine corks == With regard to density, cork used for natural wine corks usually has a mass density between 160 kg/m3 and 220 kg/m3, although it is possible to find wine corks with lower or higher densities outside that range.<ref name="Dias2015Manual">{{cite book |url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf |title=Manual Técnico Rolhas |trans-title=Technical Manual of Cork Stoppers |last=Dias |first=Jacinto |publisher=APCOR - Associação Portuguesa da Cortiça |year=2015 |location=Santa Maria de Lamas, Portugal |pages=28–29 |language=pt }}</ref>

As for moisture, in wine corks this should be between 4% and 9%, in order to maintain the appropriate balance for ideal elasticity while minimizing as much as possible the risk of microbial development.<ref name="Dias2015Manual" />

Regarding surface treatment, there are different products that can be used for this purpose, particularly paraffins and silicones.<ref name="Dias2015Manual" /> Paraffin treatments aim to waterproof the surface, in addition to providing a certain degree of lubrication.<ref name="Dias2015Manual" /> Silicone treatments, in turn, mainly aim to lubricate the wine cork so as to facilitate both bottling and the opening of the bottle.<ref name="Dias2015Manual" /> The type of treatment to be applied and its dosage depend on the type of wine, the type of bottle, the ageing time and the type of bottling machine.<ref name="Dias2015Manual" /> For example, for wines that require bottle ageing longer than 18 months, a surface treatment with paraffins should be carried out first, followed by a silicone treatment.<ref name="Dias2015Manual" />

With respect to wine cork extraction force, this tends to decrease over time while inside the bottle.<ref name="Dias2015Manual" /> Accordingly, the recommended values lie between 20 and 40 kg in the first 24 hours after bottling, although the specific legal requirements may vary depending on the product's destination market.<ref name="Dias2015Manual" />

==Attributes== thumb|Wine corks in variety Cork stoppers are moisture-resistant, are slow to deteriorate, they help wine age, and provide a waterproof seal. The stoppers are associated with a perception of high quality wine, especially as cheaper alternatives are common with lower-cost wine.<ref name="Atl"/>

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, ''Scorpex Wine Services'' |title= variability in permeability of corks and closures |url= http://www.scorpex.net/ASEVClosures2005RGibson.pdf |archive-url= https://web.archive.org/web/20130512182445/http://www.scorpex.net/ASEVClosures2005RGibson.pdf|archive-date=May 12, 2013 |year= 2005}}</ref>

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.<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|url=http://www.pfcyl.es/sites/default/files/biblioteca/amorim_lca_final_report.pdf|date=December 4, 2008|access-date=February 26, 2020|archive-date=February 26, 2020|archive-url=https://web.archive.org/web/20200226233233/http://www.pfcyl.es/sites/default/files/biblioteca/amorim_lca_final_report.pdf}}</ref><ref>{{cite web|last=Easton|first=Sally|title=Cork is the most sustainable form of closure, study finds |website=Decanter|date=4 December 2008|url=http://www.decanter.com/wine-news/cork-is-the-most-sustainable-form-of-closure-study-finds-75623/|access-date=February 26, 2020}}</ref>

===Reuse=== thumb|upright=0.6|Christmas decor from repurposed corks Wine corks cannot be reused as wine corks due to bacterial concerns, but they can be recycled into many other useful objects such as corkboards, coasters, and flooring, and used for all kinds of craft projects. While many synthetic corks can be {{ill|recycled|de|Korkrecycling}} at home, natural corks can either be composted or recycled at specific stores. Companies partner with stores to accept used corks and recycle them into other products; ReCork is the largest of these companies in the United States.<ref name="RRR">{{Cite web|url=https://www.bustle.com/p/can-you-recycle-wine-corks-heres-how-you-can-best-dispose-of-them-18010016|title=Can You Recycle Wine Corks? Here's How You Can Best Dispose of Them|date=17 June 2019 }}</ref> Corks can also be recycled through [https://corkforest.org/ Cork Forest Conservation Alliance].<ref>{{Cite web|date=2022-09-10 |title=How to recycle wine corks - Sure wine not |url=https://surewinenot.com/how-to-recycle-wine-corks/ |access-date=2022-10-17 |language=en-US}}</ref>

==Types== ===Still wine=== Corks typically are {{convert|24-25|mm}} in diameter. Lengths vary, usually based on length of time estimated to age the wine. Simple wines are commonly {{convert|38|mm}} long, medium aging wines (the most popular size) are {{convert|44|mm}}, and long aging or expensive wines are often {{convert|49-55|mm}} long.<ref name="tech" />

===Sparkling wine=== [[File:Muselet 01.jpg|thumb|left|upright=0.7|Cork and muselet on a bottle of Franciacorta]] {{multiple image|total_width=220|image1=Bouchon de champagne neuf.jpg|image2=Korken für Champagnerflasche 2018-15.JPG|footer=Champagne corks before and after usage}} Sparkling wine corks are typically {{convert|30|mm}} in diameter and {{convert|50|mm}} in length. Before insertion, a sparkling wine cork is almost 50% larger than the opening of the bottle. Originally, the cork is a cylinder and when pushed into the bottle, the corks are compressed to about 60–70 percent of their original diameters before insertion.<ref name="tech">{{cite book|url=https://books.google.com/books?id=TsxPDAAAQBAJ&pg=PT226|title=Concepts in Wine Technology, Small Winery Operations, Third Edition – Yair Margalit, PhD – Google Books|last1=Yair Margalit|first1=PhD|date=November 2012|isbn=9781935879787|access-date=27 February 2020}}</ref> The corks are held in place by wire cages known as muselets. Over time, its compressed shape becomes more permanent, assuming the iconic mushroom form.<ref name="tech" />

=== Natural cork wine corks (one-piece or solid) === Natural cork wine corks are manufactured by drilling from a single solid piece of cork.<ref name="apcor2" /><ref name="Dias2015pp28-29" /> Wine corks may be cylindrical or conical in shape. The dimensions of natural corks vary depending on the type of bottle for which they are intended.<ref name="Dias2015pp28-29">{{cite book |url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf |title=Manual Técnico Rolhas |trans-title=Technical Manual of Wine Corks |last=Dias |first=Jacinto |publisher=APCOR - Associação Portuguesa da Cortiça |date=2015 |location=Santa Maria de Lamas, Portugal |pages=28-29 |language=pt }}</ref>

{| class="wikitable" |+ ! !54x24-26 millimetres !49x24-26 millimetres !45x24-26 millimetres !38X24-26 millimetres !38X22-26 millimetres !33X21-22 millimetres |- |Bordeaux, Burgundy or Rhine-type bottle (75 cl) |Yes |Yes |Yes |Yes |Yes |No |- |50 cl bottle |No |No |Yes |Yes |Yes |Yes |- |Half-bottle (37.5 cl) |No |No |No |Yes |Yes |Yes |- |Long ageing |Yes |Yes |Yes |Yes |No |No |- |Medium ageing |No |No |No |No |Yes |Yes |}

Longer corks are most commonly used for wines associated with longer bottle ageing.<ref name="Dias2015Manual" /> However, sealing quality over time depends more on the appropriate cork diameter than on its length.<ref name="apcor2" /> Ideally, a cork should exceed the narrowest diameter of the bottle neck by at least 6 millimetres, so that it is not compressed by more than one third of its diameter when inserted, thereby avoiding damage to the cellular structure of the cork.<ref name="Dias2015Manual" />

==== Natural cork wine corks used for champagne and sparkling wine ==== thumb|left|upright=0.7|Cork and wire cage in a champagne bottle - the difference between the agglomerated cork body above and the solid cork discs below inside the neck is visible. {{multiple image|total_width=220|image1=Bouchon de champagne neuf.jpg|image2=Korken für Champagnerflasche 2018-15.JPG|footer=Sparkling wine corks before and after use}} This type of cork is specifically intended for sealing champagne, sparkling wines, carbonated wines and cider.<ref name="Dias2015p32">{{cite book|url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf|title=Manual Técnico Rolhas|trans-title=Technical Manual of Wine Corks|last=Dias|first=Jacinto|publisher=APCOR - Associação Portuguesa da Cortiça|date=2015|location=Santa Maria de Lamas, Portugal|page=32|language=pt}}</ref>

From a technical perspective, some authors classify champagne corks as a subcategory or part of the family of technical corks, since they are produced following the same method.<ref name="Dias2015p32" /> That is, these corks have a body formed by agglomerated cork, to which one, two or three discs of solid natural cork are glued at the base.<ref name="Dias2015p32" /><ref name="tech" /> This is why these corks tend to assume a mushroom shape after bottling.<ref name="tech" />

Champagne corks have a larger diameter, essential to withstand the high pressures inside sparkling-wine bottles. They usually have a diameter of 30 mm and a length of 50 mm.<ref name="tech" /> These corks are tied with a wire cage'''''<ref name=":022">{{cite web |last=Infopédia – Dicionário da Língua Portuguesa |title=gaiola |trans-title=wire cage |url=https://www.infopedia.pt/dicionarios/lingua-portuguesa/gaiola |website=Infopédia Dicionário da Língua Portuguesa |access-date=14 August 2023 |language=pt }}</ref>''''' of wire, sometimes also called a muzzle<ref name=":02">{{cite book |url=https://www.drapc.gov.pt/base/documentos/elaboracao_%20de_espumantes.pdf |title=Elaboração de espumantes |trans-title=Production of Sparkling Wines |last=Carvalheira |first=José |publisher=Direcção Regional de Agricultura e Pescas do Centro – Ministério da Agricultura Português |year=2012 |location=Castelo Branco |page=21 |language=pt }}</ref>, and this twisted-wire structure is generally accompanied by a metal plate stamped with the brand logo<ref name=":6">{{cite book |url=https://www.amazon.fr/R%C3%A9pertoire-plaques-muselets-du-champagne/dp/2956877518 |title=Répertoire des plaques de muselets du champagne: nouveautés 2017, 2018, 2019, et 2020 |trans-title=Catalogue of Champagne Muselet Caps: New Issues 2017, 2018, 2019, and 2020 |last=Lambert |first=Laurent |publisher=Lambert collections |year=2021 |location=Bassuet |page=198 |isbn=978-2956877516 |language=fr }}</ref>, and in the case of champagne bottles is often covered with foil.<ref name=":1">{{cite book |url=https://gallica.bnf.fr/ark:/12148/bpt6k63658190 |title=Au pays du Champagne : le vignoble, le vin |trans-title=In the Land of Champagne: The Vineyard and the Wine |last=Moreau-Bérillon |first=C. |publisher=Librairie L. Michaud |year=1925 |location=Reims, France |page=446 |language=fr }}</ref>

=== Multi-piece natural wine corks === This type of cork is produced from two or more pieces of natural cork glued together using adhesives suitable for food contact.<ref name="Dias2015p30">{{cite book|url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf|title=Manual Técnico Rolhas|trans-title=Technical Manual of Wine Corks|last=Dias|first=Jacinto|publisher=APCOR - Associação Portuguesa da Cortiça|date=2015|location=Santa Maria de Lamas, Portugal|page=30|language=pt}}</ref><ref name="apcor2" />

Multi-piece corks are made from thinner cork planks, insufficient for producing single-piece natural corks.<ref name="Dias2015p30" />

They are characterised by higher density values.<ref name="Dias2015p30" />

In terms of dimensions and classification, multi-piece corks generally follow the same parameters as single-piece corks.<ref name="Dias2015p30" /><ref name="apcor2" /> This type of cork is widely used in large-format bottles, since those bottles require larger cork diameters, which are more difficult to manufacture from a single piece.<ref name="Dias2015p30" />

=== Filled natural cork wine corks === This type of natural cork is characterised by having its pores (called lenticels<ref name=":0223">{{cite web|last=S.A|first=Infopédia- Dicionário da Língua Portuguesa|url=https://www.infopedia.pt/dicionarios/lingua-portuguesa/lenticela|title=lenticela|access-date=14 August 2023|website=Infopédia Dicionário da Língua Portuguesa|language=pt-pt}}</ref>) filled exclusively with cork powder in order to correct the finish of solid natural corks.<ref name="Dias2015p30" /><ref name="apcor2" />

The cork powder is fixed into the lenticels using adhesives based on natural resins and rubber.<ref name="Dias2015p30" /> This process is generally carried out using water-based products in order to remove organic solvents from the filling compounds.<ref name="apcor2" />

Filling improves both the aesthetic appearance of the cork, giving it a more uniform look, and its performance, as it benefits from improved mechanical characteristics.<ref name="Dias2015p30" />

Filled corks are produced in various formats and sizes. In cylindrical formats, the most common dimensions are<ref name="Dias2015p30" />:

{| class="wikitable" |+ ! !49x24 millimetres !38X24 millimetres !38X22 millimetres !33X21 millimetres |- |Bordeaux, Burgundy or Rhine-type bottle (75 cl) |Yes |Yes |Yes |No |- |Half-bottle (37.5 cl) |No |No |Sim |Sim |- |Medium ageing |Yes |Yes |Yes |No |}

=== Agglomerated wine corks === This type of cork is entirely produced from cork granules derived from by-products of solid cork production.<ref name=":7">{{cite book |url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf |title=Manual Técnico Rolhas |trans-title=Technical Manual of Wine Corks |last=Dias |first=Jacinto |publisher=APCOR - Associação Portuguesa da Cortiça |year=2015 |location=Santa Maria de Lamas, Portugal |pages=33–34 |language=pt }}</ref><ref name="apcor2" />

It can be manufactured either by individual moulding or by extrusion. In both methods, the binder used to hold the cork granules together is suitable for food contact.<ref name="Dias2015pp33-34">{{cite book|url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf|title=Manual Técnico Rolhas|trans-title=Technical Manual of Wine Corks|last=Dias|first=Jacinto|publisher=APCOR - Associação Portuguesa da Cortiça|date=2015|location=Santa Maria de Lamas, Portugal|pages=33-34|language=pt}}</ref>

Agglomerated corks are a more economical option for ensuring proper bottle sealing for a period that should not exceed roughly two years.<ref name=":7" /> <ref name="apcor2" />

In addition to economic advantages for lower-value wines with high turnover, they also offer the benefit of visual uniformity across the batch.<ref name=":7" />

Agglomerated corks are highly industrialised products, and their categories are defined based on cork granule size and final density of the product.<ref name=":7" /> Agglomerated corks are mainly produced in the following sizes<ref name=":7" />: {| class="wikitable" |+ ! !44x23.5 millimetres !38X23.5 millimetres !33X23.5 millimetres |- |Bordeaux, Burgundy or Rhine-type bottle (75 cl) |Yes |Yes |No |- |Half-bottle (37.5 cl) |No |No |Yes |- |Medium ageing |No |No |No |}

=== Technical wine corks === Technical corks are designed for bottling young wines intended to be consumed within roughly 2 to 3 years.<ref name="apcor2" /> They consist of a dense agglomerated cork body with 2 natural cork discs glued only to the base of the cork or with one disc glued to the top and another to the base of the cork.<ref name="Dias2015p31">{{cite book|url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf|title=Manual Técnico Rolhas|trans-title=Technical Manual of Wine Corks|last=Dias|first=Jacinto|publisher=APCOR - Associação Portuguesa da Cortiça|date=2015|location=Santa Maria de Lamas, Portugal|page=31|language=pt}}</ref>

To glue the cork discs, binders suitable for food contact are used.<ref name="Dias2015p31" /> This type of cork is chemically stable and mechanically resistant, performing reliably during the twisting it undergoes during bottling and opening.<ref name="Dias2015p31" />

According to the Australian Wine Research Institute, they have proven to be excellent seals over time, maintaining the necessary concentration of free sulfur dioxide in the bottle and thereby avoiding premature oxidation without developing unpleasant aromas.<ref name="Dias2015p31" />

The most common market formats are the following<ref name="Dias2015p31" />:

{| class="wikitable" |+ ! !44x23.5 millimetres !40 or 39X23.5 millimetres |- |Bordeaux, Burgundy or Rhine-type bottle (75 cl) |Yes |Yes |- |Half-bottle (37.5 cl) |No |Yes |- |Medium ageing |Yes |Yes |}

=== Microgranulated corks === This type of cork belongs to a new generation of cork products, characterised by an agglomerated cork body with a specific granule size distribution. This latest-generation cork product is noted for greater structural stability and sensory neutrality.<ref name="Dias2015p34">{{cite book|date=2015 |first=Jacinto |last=Dias |location=Santa Maria de Lamas, Portugal |page=34 |publisher=APCOR - Associação Portuguesa da Cortiça |title=Manual Técnico Rolhas |url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf}}</ref>

The granules in this type of granulated cork are bonded with adhesives suitable for food contact.<ref name="Dias2015p34" />

This type of cork is intended for wines meant for quick consumption, though with some palate complexity.<ref name="Dias2015p34" /> This type of cork is mainly manufactured with lengths of 49, 45-44 and 38 millimetres.<ref name="Dias2015p34" />

=== Capsule corks === These corks consist of a solid cork, to the top of which a capsule is attached, which may be made of wood, PVC, porcelain, metal, glass, among other materials.<ref name=":11">{{cite book |url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf |title=Manual Técnico Rolhas |trans-title=Technical Manual of Wine Corks |last=Dias |first=Jacinto |publisher=APCOR - Associação Portuguesa da Cortiça |year=2015 |location=Santa Maria de Lamas, Portugal |page=35 |language=pt }}</ref>

Capsule corks are usually used in fortified wines or spirits, which are ready to drink when released to market.<ref name=":11" /> This type of cork is easier to reuse, which is especially useful for this type of product, since it is generally not intended to be consumed all at once.<ref name="Dias2015p35">{{cite book|url=https://apcor.pt/uploads/Media/Brochura/2-%20Manual%20de%20rolhas/ManualRolhas_PT_VF.pdf|title=Manual Técnico Rolhas|trans-title=Technical Manual of Wine Corks|last=Dias|first=Jacinto|publisher=APCOR - Associação Portuguesa da Cortiça|date=2015|location=Santa Maria de Lamas, Portugal|page=35|language=pt}}</ref>

Examples of products that commonly use this type include many Port wines, Madeira wines, Calvados, Moscatel de Setúbal, and also some whiskies, vodkas, Cognac, Armagnac, brandies, liqueurs and spirits.<ref name=":11" />

For this type of cork, it is not necessary to exceed the internal neck diameter by 6 millimetres; exceeding it by only 2 millimetres is sufficient to achieve a proper seal and allow easy reuse.<ref name=":11" />

On the market, the most common formats correspond to the most widely used bottle sizes.<ref name=":11" /> The most common lengths for this type are: 27x20 mm; 27x19.5 mm; 27x18.5 mm; 24x17 mm (for 20 cl bottles); 18x13.5 mm (for miniature bottles).<ref name=":11" />

==See also== * Corkscrew

==References== {{reflist}}

==External links== * {{Commons category-inline|Corks}}

Category:Wine packaging and storage