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Cork is an impermeable
buoyant Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pr ...
material, the phellem layer of bark tissue that is harvested for commercial use primarily from ''
Quercus suber ''Quercus suber'', commonly called the cork oak, is a medium-sized, evergreen oak tree in the section ''Quercus'' sect. ''Cerris''. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores ...
'' (the cork oak), which is native to southwest
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
and northwest
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. Cork is composed of
suberin Suberin, cutin and lignins are complex, higher plant epidermis and periderm cell-wall macromolecules, forming a protective barrier. Suberin, a complex polyester biopolymer, is lipophilic, and composed of long chain fatty acids called suberin acid ...
, a
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, th ...
substance. Because of its impermeable, buoyant, elastic, and fire retardant properties, it is used in a variety of products, the most common of which is wine stoppers. The montado landscape of
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
produces approximately half of the cork harvested annually worldwide, with
Corticeira Amorim Corticeira Amorim S.G.P.S., S.A., is a Portuguese subholding company belonging to the Amorim Group and claims to have been the world leader in the cork industry for over 130 years, with operations in hundreds of countries all over the world. Co ...
being the leading company in the industry. Cork was examined
microscopically Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...
by
Robert Hooke Robert Hooke FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using a compound microscope that ...
, which led to his discovery and naming of the
cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...
. Cork composition varies depending on
geographic Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and ...
origin,
climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...
and
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
conditions, genetic origin, tree dimensions, age (virgin or reproduction), and growth conditions. However, in general, cork is made up of
suberin Suberin, cutin and lignins are complex, higher plant epidermis and periderm cell-wall macromolecules, forming a protective barrier. Suberin, a complex polyester biopolymer, is lipophilic, and composed of long chain fatty acids called suberin acid ...
(average of about 40%),
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
(22%),
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...
s (
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
and
hemicellulose A hemicellulose (also known as polyose) is one of a number of heteropolymer, heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all embryophyte, terrestrial plant cell walls.Scheller HV, Ulvskov H ...
) (18%), extractables (15%) and others. Text was copied from this source, which is available under
Creative Commons Attribution 4.0 International License


History

Cork is a natural material used by humanity for over 5,000 years. It is a material whose applications have been known since antiquity, especially in floating devices and as stopper for
beverages A drink or beverage is a liquid intended for human consumption. In addition to their basic function of satisfying thirst, drinks play important roles in human culture. Common types of drinks include plain drinking water, milk, juice, smoothies a ...
, mainly
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
, whose market, from the early twentieth century, had a massive expansion, particularly due to the development of several cork based agglomerates. Text was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
In
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
,
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
,
Babylon ''Bābili(m)'' * sux, 𒆍𒀭𒊏𒆠 * arc, 𐡁𐡁𐡋 ''Bāḇel'' * syc, ܒܒܠ ''Bāḇel'' * grc-gre, Βαβυλών ''Babylṓn'' * he, בָּבֶל ''Bāvel'' * peo, 𐎲𐎠𐎲𐎡𐎽𐎢 ''Bābiru'' * elx, 𒀸𒁀𒉿𒇷 ''Babi ...
, and
Persia Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
from about 3000 BC, cork was already used for sealing
container A container is any receptacle or enclosure for holding a product used in storage, packaging, and transportation, including shipping. Things kept inside of a container are protected on several sides by being inside of its structure. The term ...
s, fishing equipment, and domestic applications. In
ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
(1600 to 1100 years BC) cork was used in
footwear Footwear refers to garments worn on the feet, which typically serves the purpose of protection against adversities of the environment such as wear from ground textures and temperature. Footwear in the manner of shoes therefore primarily serves th ...
, to manufacture a type of
sandal Sandals are an open type of footwear, consisting of a sole held to the wearer's foot by straps going over the instep and around the ankle. Sandals can also have a heel. While the distinction between sandals and other types of footwear can some ...
s attached to the foot by straps, generally
leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hogs, ...
and with a sole in cork or leather. In the second century AD, a Greek physician,
Dioscorides Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of ''De materia medica'' (, On Medical Material) —a 5-vol ...
, noted several medical applications of cork, mainly for hair loss treatment. Nowadays, the majority of people know cork for its use as stoppers in
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
bottle A bottle is a narrow-necked container made of an impermeable material (such as glass, plastic or aluminium) in various shapes and sizes that stores and transports liquids. Its mouth, at the bottling line, can be sealed with an internal stopp ...
s. Cork stoppers were introduced at the beginning of the seventeenth century by the Benedictine monk
Dom Pérignon Dom Pérignon (; ) is a brand of vintage Champagne. It is named after Dom Pérignon, a Benedictine monk who was an important quality pioneer for Champagne wine but who, contrary to popular myths, did not discover the Champagne method for making ...
, who used them to seal the bottles of his famous
champagne Champagne (, ) is a sparkling wine originated and produced in the Champagne wine region of France under the rules of the appellation, that demand specific vineyard practices, sourcing of grapes exclusively from designated places within it, spe ...
. Cork stoppers were adopted in 1729 by Ruinart and in 1973 by Moët et Chandon.


Structure

Cork presents a characteristic
cellular Cellular may refer to: *Cellular automaton, a model in discrete mathematics * Cell biology, the evaluation of cells work and more * ''Cellular'' (film), a 2004 movie *Cellular frequencies, assigned to networks operating in cellular RF bands *Cell ...
structure in which the
cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
have usually a pentagonal or hexagonal shape. The cellular wall consists of a thin, lignin rich middle
lamella Lamella (plural lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal ...
(internal primary wall), a thick secondary wall made up from alternating suberin and wax lamella and a thin tertiary wall of polysaccharides. Some studies suggest that the secondary wall is lignified, and therefore, may not consist exclusively of suberin and waxes. The cells of cork are filled with a
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
mixture In chemistry, a mixture is a material made up of two or more different chemical substances which are not chemically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the ...
similar to the air, making them behave as authentic “pads,” which contributes to the capability of cork recovery after compressed.


Sources

There are about 2,200,000 hectares of cork forest worldwide; 34% in
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
and 27% in
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
. Annual production is about 300,000 tons; 49.6% from Portugal, 30.5% from Spain, 5.8% from
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
, 4.9% from
Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...
, 3.5% from
Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...
, 3.1% from
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
, and 2.6% from
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
. Once the trees are about 25 years old the cork is traditionally stripped from the trunks every nine years, with the first two harvests generally producing lower quality cork. The trees live for about 300 years. The cork industry is generally regarded as environmentally friendly. Cork production is generally considered
sustainable Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livin ...
because the cork tree is not cut down to obtain cork; only the bark is stripped to harvest the cork. The tree continues to live and grow. The
sustainability Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livi ...
of production and the easy
recycling Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...
of cork products and by-products are two of its most distinctive aspects.
Cork oak ''Quercus suber'', commonly called the cork oak, is a medium-sized, evergreen oak tree in the section ''Quercus'' sect. ''Cerris''. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores ...
forests also prevent
desertification Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by ...
and are a particular habitat in the
Iberian Peninsula The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, defi ...
and the refuge of various
endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...
.
Carbon footprint A carbon footprint is the total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, place or product, expressed as carbon dioxide equivalent (CO2e). Greenhouse gases, including the carbon-containing gases carbo ...
studies conducted by
Corticeira Amorim Corticeira Amorim S.G.P.S., S.A., is a Portuguese subholding company belonging to the Amorim Group and claims to have been the world leader in the cork industry for over 130 years, with operations in hundreds of countries all over the world. Co ...
, Oeneo Bouchage of France and the Cork Supply Group of Portugal concluded that cork is the most environmentally friendly
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
stopper Stopper may refer to: * Bung, a plug used to stop the opening of a container ** Laboratory rubber stopper, a specific type of bung * Plug (sanitation), used to stop a drainage outlet * Defender (association football), in soccer (association footba ...
in comparison to other alternatives. The
Corticeira Amorim Corticeira Amorim S.G.P.S., S.A., is a Portuguese subholding company belonging to the Amorim Group and claims to have been the world leader in the cork industry for over 130 years, with operations in hundreds of countries all over the world. Co ...
’s study, in particular ("Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures"), was developed by
PricewaterhouseCoopers PricewaterhouseCoopers is an international professional services brand of firms, operating as partnerships under the PwC brand. It is the second-largest professional services network in the world and is considered one of the Big Four accounting ...
, according to ISO 14040. Results concluded that, concerning the emission of greenhouse gases, each plastic stopper released 10 times more CO2, whilst an aluminium screw cap releases 26 times more CO2 than does a cork stopper. For example, to produce 1,000 cork stoppers 1.5 kg are emitted, but to produce the same amount of plastic stoppers 14 kg of are emitted and for the same amount of aluminium screw caps 37 kg are emitted. The cork oak is unrelated to the "cork trees" (''
Phellodendron ''Phellodendron'', or cork-tree, is a genus of deciduous, dioecious trees in the family Rutaceae, native to east and northeast Asia. It has leathery, pinnate leaves and yellow, clumped flowers. The name refers to the thick and corky bark of some ...
''), which have corky bark but are not used for cork production.


Harvesting

Cork is extracted only from early May to late August, when the cork can be separated from the tree without causing permanent damage. When the tree reaches 25–30 years of age and about 24 in (60 cm) in circumference, the cork can be removed for the first time. However, this first harvest almost always produces poor quality or "virgin" cork (Portuguese ''cortiça virgem''; Spanish ''corcho bornizo'' or ''corcho virgen''). Bark from initial harvests can be used to make flooring, shoes, insulation and other industrial products. Subsequent extractions usually occur at intervals of 9 years, though it can take up to 13 for the cork to reach an acceptable size. If the product is of high quality it is known as "gentle" cork (Portuguese ''cortiça amadia'', but also ''cortiça secundeira'' only if it is the second time; Spanish ''corcho segundero'', also restricted to the "second time"), and, ideally, is used to make stoppers for wine and champagne bottles. The workers who specialize in removing the cork are known as extractors. An extractor uses a very sharp axe to make two types of cuts on the tree: one horizontal cut around the plant, called a crown or necklace, at a height of about 2–3 times the circumference of the tree, and several vertical cuts called rulers or openings. This is the most delicate phase of the work because, even though cutting the cork requires significant force, the extractor must not damage the underlying
phellogen Cork cambium (pl. cambia or cambiums) is a tissue found in many vascular plants as a part of the epidermis. It is one of the many layers of bark, between the cork and primary phloem. The cork cambium is a lateral meristem and is responsible fo ...
or the tree will be harmed. To free the cork from the tree, the extractor pushes the handle of the axe into the rulers. A good extractor needs to use a firm but precise touch in order to free a large amount of cork without damaging the product or tree. These freed portions of the cork are called planks. The planks are usually carried off by hand since cork forests are rarely accessible to vehicles. The cork is stacked in piles in the forest or in yards at a factory and traditionally left to dry, after which it can be loaded onto a truck and shipped to a processor.


Properties and uses

Cork's
elasticity Elasticity often refers to: *Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress Elasticity may also refer to: Information technology * Elasticity (data store), the flexibility of the data model and the cl ...
combined with its near-impermeability makes it suitable as a material for
bottle A bottle is a narrow-necked container made of an impermeable material (such as glass, plastic or aluminium) in various shapes and sizes that stores and transports liquids. Its mouth, at the bottling line, can be sealed with an internal stopp ...
stoppers, especially for
wine bottle A wine bottle is a bottle, generally a glass bottle, that is used for holding wine. Some wines are fermented in the bottle while others are bottled only after fermentation. Recently the bottle has become a standard unit of volume to describe sal ...
s. Cork stoppers represent about 60% of all cork based production. Cork has an almost zero
Poisson's ratio In materials science and solid mechanics, Poisson's ratio \nu ( nu) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading. The value of Pois ...
, which means the radius of a cork does not change significantly when squeezed or pulled. Cork is an excellent
gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to c ...
material. Some
carburetor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...
float bowl gaskets are made of cork, for example. Cork is also an essential element in the production of
badminton Badminton is a racquet sport played using racquets to hit a shuttlecock across a net. Although it may be played with larger teams, the most common forms of the game are "singles" (with one player per side) and "doubles" (with two players pe ...
shuttlecock A shuttlecock (also called a birdie or shuttle) is a high-drag projectile used in the sport of badminton. It has an open conical shape formed by feathers or plastic (or a synthetic alternative) embedded into a rounded cork (or rubber) base. T ...
s. Cork's bubble-form structure and natural fire retardant make it suitable for acoustic and
thermal insulation Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...
in house walls, floors, ceilings, and facades. The by-product of more lucrative stopper production, corkboard is gaining popularity as a non-allergenic, easy-to-handle and safe alternative to petrochemical-based insulation products. Sheets of cork, also often the by-product of stopper production, are used to make
bulletin boards A bulletin board (pinboard, pin board, noticeboard, or notice board in British English) is a surface intended for the posting of public messages, for example, to advertise items wanted or for sale, announce events, or provide information. B ...
as well as floor and wall tiles. Cork's low
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
makes it a suitable material for
fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment, but may also be caught from stocked bodies of water such as ponds, canals, park wetlands and reservoirs. Fishing techniques inclu ...
floats and buoys, as well as handles for
fishing rod A fishing rod is a long, thin rod used by angling, anglers to fishing, catch fish by manipulating a fishing line, line ending in a fish hook, hook (formerly known as an ''angle'', hence the term "angling"). At its most basic form, a fishing ...
s (as an alternative to
neoprene Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene.Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion R ...
). Granules of cork can also be mixed into
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
. The composites made by mixing cork granules and cement have lower thermal conductivity, lower density, and good energy absorption. Some of the property ranges of the composites are density (400–1500 kg/m3), compressive strength (1–26 MPa), and flexural strength (0.5–4.0 MPa).


Use in wine bottling

As late as the mid-17th century, French
vintners A winemaker or vintner is a person engaged in winemaking. They are generally employed by wineries or wine companies, where their work includes: *Cooperating with viticulturists *Monitoring the maturity of grapes to ensure their quality and to deter ...
did not use cork stoppers, using instead oil-soaked rags stuffed into the necks of bottles. 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". Natural cork closures are used for about 80% of the 20 billion bottles of
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
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. 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. Since the mid-1990s, a number of wine brands have switched to
alternative wine closure Alternative wine closures are substitute closures used in the wine industry for sealing wine bottles in place of traditional cork closures. The emergence of these alternatives has grown in response to quality control efforts by winemakers to pr ...
s such as
plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
stoppers, 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-
EEC The European Economic Community (EEC) was a regional organization created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisb ...
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. These alternatives to cork have both advantages and disadvantages. For example, screwtops are generally considered to offer a 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. TCA is the main documented cause of
cork taint Cork taint is a broad term referring to a wine fault characterized by a set of undesirable smells or tastes found in a bottle of wine, especially spoilage that can only be detected after bottling, aging and opening. Though modern studies have sh ...
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. Stoppers which resemble natural cork very closely can be made by isolating the suberin component of the cork from the undesirable
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
, 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. Composite corks with real cork veneers are used in cheaper wines. Celebrated Australian wine writer and critic 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. The study "Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures," conducted by
PricewaterhouseCoopers PricewaterhouseCoopers is an international professional services brand of firms, operating as partnerships under the PwC brand. It is the second-largest professional services network in the world and is considered one of the Big Four accounting ...
and commissioned by a major cork manufacturer, Amorim, concluded that cork is the most environmentally responsible stopper, in a one-year
life cycle analysis Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case of ...
comparison with plastic stoppers and aluminum screw caps.


Other uses

* On 28 November 2007, the Portuguese national postal service
CTT CTT – Correios de Portugal, S.A. () is a Portuguese company that operates as both the national postal service of Portugal and a commercial group with subsidiaries operating in banking, e-commerce, and other postal services. It was founded in ...
issued the world's first
postage stamp A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the fa ...
made of cork. * In musical instruments, particularly
woodwind instrument Woodwind instruments are a family of musical instruments within the greater category of wind instruments. Common examples include flute, clarinet, oboe, bassoon, and saxophone. There are two main types of woodwind instruments: flutes and Reed ...
s, where it is used to fasten together segments of the instrument, making the seams airtight. Low quality conducting baton handles are also often made out of cork. * In shoes, especially those using welt construction to improve climate control and comfort. * Because it is impermeable and moisture-resistant, cork is often used as an alternative to leather in
handbag A handbag, commonly known as a purse or pocketbook in North American English, is a handled medium-to-large bag used to carry personal items. Purse, handbag or pouch The term "purse" originally referred to a small bag for holding coins. In many ...
s,
wallet A wallet is a flat case or pouch often used to carry small personal items such as paper currency, credit cards; identification documents such as driver's license, identification card, club card; photographs, transit pass, business cards and oth ...
s, and other fashion items. * To make
brick A brick is a type of block used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a block composed of dried clay, but is now also used informally to denote other chemically cured cons ...
s for the outer walls of houses, as in Portugal's pavilion at
Expo 2000 Expo 2000 was a World Expo held in Hanover, Germany from 1 June to 31 October 2000. It was located on the Hanover Fairground (Messegelände Hannover), which is the largest exhibition ground in the world. Initially some 40 million people were expe ...
. * As the core of both
baseballs A baseball is a ball used in the sport of the same name. The ball consists of a rubber or cork center wrapped in yarn and covered with white natural horsehide or cowhide, or a synthetic composite leather. A regulation baseball is 9 to 9¼ inche ...
and
cricket ball A cricket ball is a hard, solid ball used to play cricket. A cricket ball consists of a cork core wound with string then a leather cover stitched on, and manufacture is regulated by cricket law at first-class level. The trajectory of a crick ...
s. A
corked bat In baseball, a corked bat is a specially modified baseball bat that has been filled with cork or other lighter, less dense substances to make the bat lighter. A lighter bat gives a hitter a quicker swing and may improve the hitter's timing. Despit ...
is made by replacing the interior of a
baseball bat A baseball bat is a smooth wooden or metal club used in the sport of baseball to hit the ball after it is thrown by the pitcher. By regulation it may be no more than in diameter at the thickest part and no more than in length. Although histor ...
with cork – a practice known as "corking". It was historically a method of cheating at
baseball Baseball is a bat-and-ball sport played between two teams of nine players each, taking turns batting and fielding. The game occurs over the course of several plays, with each play generally beginning when a player on the fielding tea ...
; the
efficacy Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as ''effectiveness'', and it has often been used synonymously, although in pharmacology a pragmatic clinical trial#Efficacy versu ...
of the practice is now discredited. * In various forms, in spacecraft
heat shields In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
and fairings. * In the paper pick-up mechanisms in
inkjet Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensi ...
and
laser printers Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" to d ...
. * To make later-model
pith helmet The pith helmet, also known as the safari helmet, salacot, sola topee, sun helmet, topee, and topi) is a lightweight cloth-covered helmet made of sholapith. The pith helmet originates from the Spanish Empire, Spanish military adaptation of the na ...
s. * Hung from hats to keep insects away. (''See ''
cork hat A cork hat is a type of headgear with corks strung from the brim, to ward off insects. Pieces of cork, typically bottle corks, are hung on strings from the brim of the hat. The low density of cork means a number of pieces may hang from a ha ...
) * As a core material in sandwich composite construction. * As the friction lining material of an
automatic transmission An automatic transmission (sometimes abbreviated to auto or AT) is a multi-speed transmission used in internal combustion engine-based motor vehicles that does not require any input from the driver to change forward gears under normal driving c ...
clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...
, as designed in certain
mopeds A moped ( ) is a type of small motorcycle, generally having a less stringent licensing requirement than full motorcycles or automobiles. The term used to mean a similar vehicle except with both bicycle pedals and a motorcycle engine. Mopeds typi ...
. * Alternative of wood or aluminium in automotive interiors. * Cork slabs are sometimes used by orchid growers as a natural mounting material. * Cork paddles are used by glass blowers to manipulate and shape hot molten glass. * Many racing bicycles have their handlebars wrapped in cork-based tape manufactured in a variety of colors. * To make
architectural model An architectural model is a type of scale model made to study aspects of an architectural design or to communicate design intent. They can be made from a variety of materials such as paper, plaster, plastic, resin, wood, glass and metal. They ...
s.


See also

*
Bung A stopper or cork is a cylindrical or conical Closure (container), closure used to seal a container, such as a bottle, tube or barrel (storage), barrel. Unlike a Lid (container), lid or bottle cap, which encloses a container from the outside wit ...
* Cork Boat (vessel) *
Cork borer A cork borer, often used in a chemistry or biology laboratory, is a metal tool for cutting a hole in a cork or rubber stopper to insert glass tubing. Cork borers usually come in a set of nested sizes along with a solid pin for pushing the remov ...
*
Cork cambium Cork cambium (pl. cambia or cambiums) is a tissue found in many vascular plants as a part of the epidermis. It is one of the many layers of bark, between the cork and primary phloem. The cork cambium is a lateral meristem and is responsible fo ...
*
Corkscrew A corkscrew is a tool for drawing corks from wine bottles and other household bottles that may be sealed with corks. In its traditional form, a corkscrew simply consists of a pointed metallic helix (often called the "worm") attached to a hand ...
* Corky


Notes


References

* Margarida Pi i Contallé. 2006. Laboratory head i
Manuel SerraHongos y micotoxinas en tapones de corcho. Propuesta de límites micológicos aceptables


corkfacts.com
Instituto de Promoción del Corcho, Extremadura
iprocor.org
Analysis of the life cycle of Cork, Aluminium and Plastic Wine Closures
* Henley, Paul, ''BBC.com'' (18 September 2008)
"Urging vintners to put a cork in it"
*
PricewaterhouseCoopers PricewaterhouseCoopers is an international professional services brand of firms, operating as partnerships under the PwC brand. It is the second-largest professional services network in the world and is considered one of the Big Four accounting ...
/ECOBILAN (October 2008)
Analysis of the life cycle of Cork, Aluminium and Plastic Wine ClosuresCork - Forest in a Bottle.
2008.


External links


Cork Quality Council



Material Properties Data: CorkCork Recycling Initiative.
2017. {{DEFAULTSORT:Cork (Material) Wine packaging and storage Non-timber forest products Materials Plant anatomy Plant morphology