Cork has unique, unbeatable qualities that no human invention has managed to imitate or improve:
Lightness: because 88% of its volume is air, making it low-density.
Elasticity: it is able to return to its initial volume after being depressed, which makes it a good material to use as a stopper. Cork can be compressed up to half of its length without losing any flexibility and recover its shape and volume when it is no longer under pressure.
High friction coefficient: cork’s surface is covered with tiny suckers that make it adhere strongly and non-slippery.
Impermeability: it is very difficult for liquids and gases to pass through cork because of the suberin and ceroids in its cell walls, which makes cork practically impermeable to liquids and gases. Its resistance to moisture allows it to age without deteriorating. Several wine amphorae have been found in the sea with their cork stoppers perfectly intact.
High combustion heat: cork’s heat-generating capacity is equivalent to charcoal, around 7,000 Kcal/kg.p>
Easy to handle: artificially modifying the water content of cork by boiling it can aid industrial processes, in particular cutting, by making it softer and more elastic.
Low-water content: once the outer bark has been removed, cork’s moisture balance does not exceed 9% of its weight and is normally 6%. This low moisture makes it impossible for micro-organisms to proliferate.
Thermal insulator: cork’s natural purpose is to protect the living parts of the tree that makes it. Its honeycomb structure (which prevents air circulation), its low water content and its compounds’ low conductivity make it an effective insulator. It is thirty times more effective than concrete as an insulator.