Product Code Database
Cork is an impermeable buoyancy material. It is the Cork cambium of bark tissue which is harvested for commercial use primarily from Quercus suber (the cork oak), which is native to southwest Europe and northwest Africa. Cork is composed of suberin, a hydrophobic 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 .
The montado landscape of Portugal produces approximately half of the cork harvested annually worldwide, with Corticeira Amorim being the leading company in the industry. Cork was examined microscopically by Robert Hooke, which led to his discovery and naming of the cell.
Cork composition varies depending on Geography origin, climate and soil conditions, Genetics origin, tree dimensions, age (virgin or reproduction), and growth conditions. However, in general, cork is made up of suberin (average of about 40%), lignin (22%), (cellulose and hemicellulose) (18%), extractables (15%) and others. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
In China, Egypt, Babylon, and Persia from about 3000 BC, cork was already used for sealing , fishing equipment, and domestic applications. In ancient Greece (1600 to 1100 years BC) cork was used in footwear, to manufacture a type of attached to the foot by straps, generally leather and with a sole in cork or leather.
In the second century AD, a Greek physician, Dioscorides, 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 . The innovation of using cork as stopper can be traced back to the late 17th century, attributed to Dom Pierre Pérignon. Cork stoppers were adopted in 1729 by Ruinart and in 1973 by Moët et Chandon.
The cork industry is generally regarded as environmentally friendly. Cork production is generally considered sustainable 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 of production and the easy recycling of cork products and by-products are two of its most distinctive aspects. Cork oak forests also prevent desertification and are a particular habitat in the Iberian Peninsula and the refuge of various endangered species.
Carbon footprint studies conducted by Corticeira Amorim, Oeneo Bouchage of France and the Cork Supply Group of Portugal concluded that cork is the most environmentally friendly wine stopper in comparison to other alternatives. The Corticeira Amorim's study, in particular ("Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures"), was developed by PricewaterhouseCoopers, according to ISO 14040. Results concluded that, concerning the emission of greenhouse gases, each plastic stopper released 10 times more Carbon dioxide, 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 Chinese cork oak is native to East Asia and is cultivated in a limited extent in China; the cork produced is considered inferior to Q. suber and are used to produce agglomerated cork products.
The so-called "cork trees" (Phellodendron) are unrelated to the cork oak, they have corky bark but not thick enough for cork production.
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 two to three 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 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.
Bark from initial harvests can be used to make flooring, shoes, insulation and other industrial products. Subsequent extractions usually occur at intervals of nine years, though it can take up to thirteen for the cork to reach an acceptable size. If the product is of high quality it is known as gentle cork (Portuguese cortiça amadia,Amadio comes from and is a synonym of amavio, "beberage or spell to seduce" (Dicionário Houaiss da Língua Portuguesa), from amar, "to love". 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.
Cork is an excellent gasket material. Some carburetor float bowl gaskets are made of cork, for example.
Cork is also an essential element in the production of badminton .
Cork's bubble-form structure and natural fire retardancy make it suitable for acoustic and thermal insulation 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.
Cork is also used to make vinyl record slipmats, due to its ability to not attract dust. They also dampen static and vibrations.
Sheets of cork, also often the by-product of stopper production, are used to make bulletin boards as well as flooring.
Cork's low density makes it a suitable material for fishing floats and buoys, as well as handles for (as an alternative to neoprene).
Granules of cork can also be mixed into concrete. 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).Karade SR. 2003. An Investigation of Cork Cement Composites. PhD Thesis. BCUC. Brunel University, UK.
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 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 closures such as plastic 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 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.
The alternatives to cork have both advantages and disadvantages. For example, screwtops are generally considered to offer a Cork taint (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 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, 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., The Wine Society 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 and commissioned by a 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.
|
|
