Cork has been used in construction since ancient times. Its capacity for insulation and lightness, as well as its resistance to bad weather, make this material a perfect piece of architecture. The appearance of cork agglomerates makes it possible to have a wide range of materials with specific and defined dimensions for their use. How was the cork house built?
The form of presentation of the cork agglomerates and their fundamental and intrinsic technological characteristics to the raw material, have an origin and explanation in their cellular construction. In other words, this is original and unrepeatable. Above all, cork is a plant tissue formed by cells in the shape of a regular polyhedron with 14 faces grouped in such a way that they do not leave any intercellular space. For instance, these dead cells are found in number of 30 to 40 million per cm3. This completely impermeable fabric would prevent the necessary communication between the living cells of the bast and the atmosphere. To avoid this, the testicular canals are reddish in color due to the oxidation of tannins.
The intercellular membrane has an extraordinary originality and complexity. Each wall that separates two adjacent cells is made up of five intimately joined lamellae of unequal thickness. As a wall, it is common to two cells, so each membrane is actually double.
Thus, it is made up of two outer lamellae of a cellulosic nature. Two thicker lamellae formed in turn by 100 to 150 alternate layers of suberin and wax, as well as a double central lamella that is lignified. The cells are interconnected by tiny channels called plasmodesmata. The different nature of the cellulosic fibers of suberin, wax and lignin, are perfectly arranged to act as a membrane of great tenacity and resistance. All this thanks to cellulose. In addition, it is absolutely waterproof thanks to the wax. Similarly, it has great chemical resistance due to suberin and adequate resistance in the axial direction thanks to lignin.
This description explains the unique characteristics of cork and its technological peculiarities which make it useful if not indispensable in so many applications. In addition, it should be noted that nature has forged a structure that is absolutely irreproducible by artificial means. How could a foamed material with cells formed by lamellae of different nature properly ordered be achieved?