Cork, the offspring of well—phellem plants, it also called tegument of phellem, the main trees of growing cork are treenail and phellem. They are usually grown up in 20 or above 20 years, the tree of 20--diameter can be peeled first time, the outcome of it can be called the first—tegument or new-born tegument. Every 10—20 years, it can be peeled continuously, the tegument we get called second—born tegument, the thickness is above 2 cm. The cork is made up of 14 facet dead-cells, between them, they were laid by hexagram prism. The typical cell's diameter is 30 microns, the thickness of cell is 1—2 microns, there is no trachea between cells and the inner of cell is filled with air. The neighbouring cell is made up of 5 layers, 2 of them are fibre, the next two layers is phellem, the middle of it is wooden layer. There are 40000000 cells in per cubic centimetre, this structure makes cork good-elasticity, pressurizztion, heat—insulation, noise—absorption, insulation and rub-tolerance, besides it has the characters of insipidity, innocuity, low-proportion, soft and hard-to-burn advantages. We can not find any artificial products superior to it. In the chemical aspect, esters made of some hydroxy fatty acids and phenolphthalein is the compound of cork.

   This kind of material is cauterisationtolerance, chemical-erodation prevention, besides the erodation of dense nitric acid and dense vitriol, it has no chemical effect on fatty, oil, organic acid, salt and esters.
   Cork is the outer layer of cork-oak, is the precious reproducible green resource, it is grown in the unique—climate MED seacoast area, the global annual output is 350000 tons. After 25-year growth, the tegument peeled from the tree first time( the tegument is