When you see a cork you probably don’t realize that it is made from the bark of a particular tree. That tree is called the cork oak (Quercus suber), and is native to southwest Europe and northwest Africa. This tree has strange spongy bark which gives cork its unique qualities.
Cork is a remarkable material that is very light weight, yet impermeable to liquids and gases. It is compressible but still holds its structure, it is an excellent insulator, and contains a natural fire retardant. Cork is most commonly used to make stoppers for wine bottles, but it is also used to make flooring, automotive gaskets, and even insulation. As of yet, there has not been found any other material that combines the same characteristics as cork does.
Harvesting cork is considered a very sustainable practice because the bark is stripped off trees without cutting the tree down. Trained workers use special axes to cut the bark off these trees without damaging the live cambium underneath. They harvest the bark approximately every 9 years, and the first two times the bark is harvested it is considered lower quality and is used for making things like flooring. After the third harvesting cork bark is considered high quality and is used for the best quality wine stoppers.
The bark is harvested in the summer when it is dry and easily falls of the tree so as not to damage the live wood underneath. After harvest the tree quickly forms new layers of bark and restores its protective layer. It takes about 25 years for a cork oak to become big enough for harvesting, but these trees can live for as long as 200 to 300 years and can produce millions of corks per tree throughout its lifetime.
Portugal and Spain are the leading producers of cork, with Portugal producing approximately 50% of cork harvested annually worldwide. However, the demand for cork is slowly decreasing over time as wine producers look for cheaper ways of sealing their bottles with plastic or metal caps. If the demand for cork continues to decrease cork farmers will be forced to replace their cork forests with more conventional crops, but for now there is still some demand as other products are being made from this unique substance such as flooring and even shoes and other clothing.