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Cork (material)

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**1. Cork: History, Sources, and Harvesting**
– Cork has been used by humans for over 5,000 years, known for its versatility in ancient times.
– The innovation of cork stoppers can be traced back to the 17th century.
– Cork is sourced from 2,200,000 hectares of cork oak forests in the Mediterranean basin, with Portugal and Spain having the most managed habitats.
– Annual cork production is around 300,000 tons, harvested every nine years without cutting down trees.
– Harvesting is done from May to August, with extractors making horizontal and vertical cuts on trees to remove cork using a sharp axe.

**2. Cork: Structure and Properties**
– Cork has characteristic pentagonal/hexagonal cells with thin lignin-rich middle lamella, a secondary wall made of suberin and wax, and a tertiary wall composed of polysaccharides.
– The cells are filled with a gas mixture for elasticity.
– Cork is lightweight, buoyant, impermeable to liquids and gases, resilient to wear and tear, fire-resistant, and insulating.
– It has an almost zero Poissons ratio and is used in various products like gaskets, shuttlecocks, insulation, fishing floats, and more.
– Cork’s impermeability and elasticity make it suitable for stoppers, especially in wine bottling.

**3. Cork: Industrial and Technological Applications**
– Cork is used in various industries such as wine stoppers, flooring, wall coverings, automotive components, and aerospace materials.
– It is essential for acoustic and thermal insulation and is used in fashion accessories.
– Technological advancements have led to the development of composite materials, innovative production processes, and research on cork properties and applications.
– Cork-based materials offer advantages in modern design and different industries.

**4. Cork: Environmental Impact and Cultural Significance**
– Cork is a renewable and sustainable material, biodegradable, and recyclable, with a low carbon footprint.
– It promotes biodiversity in cork oak forests, supports rural economies, and reduces deforestation.
– Culturally, cork holds a traditional significance in Mediterranean regions, symbolizing quality in the wine industry, and is used in arts, crafts, and historical contexts.
– Cork is integrated into local customs and traditions, especially notable in Portugal.

**5. Cork: Use in Wine Bottling and Other Applications**
– Natural cork closures are used for 80% of wine bottles, allowing proper wine aging through oxygen interaction.
– Cork wine stoppers are making a comeback despite alternatives like plastic stoppers and screw caps.
– Cork is used in woodwind instruments, shoes, baseballs, cricket balls, spacecraft components, and more.
– It serves as a core material in various products and is known for its comfort, climate control, and insulating properties.

Cork (material) (Wikipedia)

Cork is an impermeable buoyant material. It is the phellem layer 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 wine stoppers.

Untreated cork panel

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 geographic origin, climate and soil conditions, genetic 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%), polysaccharides (cellulose and hemicellulose) (18%), extractables (15%) and others.

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