Cork is an impermeable buoyant material, the phellem layer of bark tissue that 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. 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. 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, mainly wine, whose market, from the early twentieth century, had a massive expansion, particularly due to the development of several cork based agglomerates. In China, Egypt, Babylon, and Persia from about 3000 BC, cork was already used for sealing containers, fishing equipment, and domestic applications. In ancient Greece (1600 to 1100 years BC) cork was used in footwear, to manufacture a type of sandals 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 bottles. Cork stoppers were adopted in 1729 by Ruinart and in 1973 by Moët et Chandon. Structure Cork presents a characteristic cellular structure in which the cells have usually a pentagonal or hexagonal shape. The cellular wall consists of a thin, lignin rich middle lamella (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 mixture similar to