The Latin word cortex derived from the Mozarabic word kórčo , which in turn came to our language as cork . That is the name given to the plant tissue formed by cells that, through a chemical transformation, present the cellulose of their membrane converted into suberin (an elastic and waterproof substance).
Cork is found in the roots, branches and peripheral sector of the trunk of certain trees , such as the Mediterranean cork oak . It generally appears as thin sheets that form layers.
To extract the cork, an ax is used to remove the bark from the tree. In this way, cork sheets are obtained, which are stacked for at least six months so that the material stabilizes.
Then begins the industrial treatment of cork , which can be developed in different ways. The plates are usually boiled for one hour and then cured for a year. Once cured, the cork is boiled again and finally cut.
On the other hand, with the remains of the boards and the lowest quality cork, after a process of crushing, binding and pressing, an agglomerated material is produced that has several uses.
In the field of botany, the plant tissue that we commonly call cork is known as phelema or suber . It is dead tissue that covers the entire trunk of the tree to protect its interior from different types of damage, such as the action of certain animals and insects or desiccation.
Suberin , mentioned above, is the fundamental component of cork. It is a natural polymer produced by the walls of certain plant cells. In the same way as cutin (a macromolecule found in land plants), suberin is composed of fatty acid hydroxides and epoxides that are linked through ester bonds.
Needless to say, cork is a product of great importance throughout the world, partly due to the popularity of alcoholic beverages that are usually bottled and protected from the outside by means of a stopper made of this material. Every year, 340,000 tons of cork are produced worldwide , and the leading country is Portugal, with a volume that exceeds 60%.
The qualities of cork are very particular, and make it especially attractive to humans:
* lightness : its density is low because almost 90% of its volume is made up of air;
* elasticity : cork can recover its initial volume after being subjected to a certain deformation, and this can be seen in the lids made of this material. It allows compression close to 50% without losing the possibility of returning to its original shape and volume;
* high coefficient of friction : thanks to having a large number of microsuction cups on its surface, it adheres easily, something that makes it reliable for sealing bottles;
* impermeability : thanks to the presence of ceroids and suberin in its cells, it is not easy for a gas or liquid to pass through its structure ;
* thermal insulation : since its natural function is to protect the trunk of the cork oak , cork has among its properties the ability to resist the passage of heat.
One of the most common uses of cork is to create stoppers for glass bottles . Most wine bottles, for example, are closed with a cork stopper.
Cork is also used to make panels . By hanging a cork board on a wall , notes can be pinned with thumbtacks or pins, establishing a bulletin board or reminders.