Views:2 Author:Site Editor Publish Time: 2019-06-11 Origin:Site
As the saying goes, "trees are afraid of peeling." Many trees soon die when their bark is stripped off, having been cut off from water and food.
There is, however, one species of tree that does not mind peeling: the deciduous or evergreen cork oak of the fagaceae (fagaceae). Cork oak bark called cork, the international known as cork. Its cells are mostly quadrilateral in cross-section and hexagonal in vertical section, coated with resin, containing up to 40 million to 500 million such cells per cubic centimeter, and about half of its volume is air, so the texture is particularly light soft, soft touch molds such as cotton wool.
Cork oak bark is not only soft, and thick, a 15 cm thick sapling, cork layer up to 2 cm thick, diameter level bigger cork layer is also thicker, its thickest person can reach 15 cm above, more than the sapling wood diameter. One might ask, after cork oak is peeled, why can still grow?
Originally, cork is the cork layer of cork oak only. Its trunk is divided into three layers: the inner part is xylem, the middle part is cork regeneration, and the outer part is cork layer. Cork of cork oak is stripped completely, although already cannot participate in metabolism again, but its cork is regenerative ministry still has regenerative ability, do not affect the growth of the tree, and after peeling, the new cork of orange yellow can grow afresh. Quercus variabilis grows slowly, bark grows 2 millimeter every year only. Plant commonly 20 years or so just begin to collect peel, call "native cork" or "virgin skin".After the first exploitation, the second exploitation shall be carried out after five or six years or eight or nine years. Cork oak can live for 180 years, so it can be extracted more than 10 times. Cork is picked from the tree after peeling, carry into the factory not to undertake processing processing immediately, pile up however open air storage yard, allow its wind to blow, insolation and rain drench, this paragraph of time wants half an year at least, the purpose depends on going its green, make color blacker, interior structure becomes densier some.
When processing, workers have to put the cork baling in 100 ℃ water worse, lasted about 1 hour and 15 minutes. This process is very important, can remove the salt in cork, tannic acid, colloid, and eliminate pests and bacteria. The cork after boiling, place indoor about 20 days in turn level ground, make its air dry.
At this moment cork becomes flat straight, soft, extremely rich flexibility, facilitate undertake processing. Besides having flexibility, cork still has the characteristic such as odorless, nontoxic, not easy catch fire and wear well. In the meantime, it still has specific gravity light, impervious to water, impervious to air, acid-alkali resistant and have insulating property to heat, electricity, sound, be regarded as insulation, insulation, shockproof, moistureproof, sound insulation by people ideal material.
Because it is not only light, heat, moisture, sound insulation, and beautiful generous, having a unique style. In recent years it has also been spotted by scientists for use in spaceships. Quercus variabilis is widely distributed, but its main producing area is in the Mediterranean countries of north Africa. Portugal grows the most among them, in this area is less than 90 thousand square kilometer country, grow the cork oak that has more than 800 thousand hectares however, produce the high-quality cork that accounts for world total output 56% every year, it is the biggest cork producer on the world. Quercus variabilis also grows in some mountainous areas of north and south China, from liaoning in the north to yunnan in the south, and also in Taiwan.