Why is Cork So Light?
Cork comes from the outer bark of a tree known as the cork oak tree. Cork has excellent insulating and water-resistant qualities. Its thin-walled cells form a matrix of air pockets and because of this it is very light in weight. It is much lighter than water and keeps floating on water because water cannot easily penetrate the walls of its cells which remain filled with air.
The cork oak trees are grown extensively in Spain and Portugal and most of the world’s cork supply comes from these places. These trees are tall – from six to twelve metres high, and can be about one metre in diameter.
To obtain cork the tree should be about twenty years old. The bark of this tree is stripped and the tree is allowed to grow its bark again. After nine years, again another stripping is taken. The cork obtained from these first two stripping is not of best quality. The third and all the subsequent stripping, each after nine year duration for about a hundred years, produce cork of good quality.
The use of cork as bottle stopper has been popular since long. Its use for floats and life-preservers is also very old. Its tiny cells act like balloons, compressing with pressure and going back to original size when released. Because of this resilience, cork has been used to cushion heavy machinery.
Cork has a long life and does not deteriorate easily. It is tasteless and odorless. Its excellent soundproofing and insulating qualities make it very useful in insulating warehouses, freezers and refrigerators and in soundproofing rooms.