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Wood Density And Wood Properties
Jun 04, 2017

      Density is the quality of a certain object per unit volume, usually expressed as g/c㎥ or kg/㎥. The density varies slightly with tree species and the density of different wood is expressed as kg/㎥.

Wood density is an important index of wood properties, which has very important practical significance. According to the actual weight of wood has been estimated, to deduce wood properties include shrinkage, swelling, hardness, strength and other physical and mechanical characters of wood.


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Wood density commonly divide to: basic density and air-dry density.


Ⅰ. Basic density

      The basic density is suitable to compare wood property as dry wood weight and raw wood (or impregnated wood) volume is relatively stable, and the result of determination is accurate. In the wood drying and antisepsis industry, it is also practical.


Ⅱ. Air-dry density

     The air-dry density is the ratio of air-dry wood weight to air-dry wood volume, and the density of wood is usually air-dry density as the moisture content at 8% to 20%. The air-dry density of wood is the basic basis for wood property comparison and production use in China.


      The air-dry density is in gram per cubic centimeter. With high air-dry density indicates the heavy wood weight, hardness and high strength. So it's an intensity indicator. Wood floors generally require more than 0.6 of the air-dry density.

      

      The wood density is affected by many factors. The main influence factors are: wood moisture content, cell wall thickness, ring width, fiber ratio, extract content, parts of the trunk and age of site conditions and silvicultural measures etc. China Wood Industry Research Academy of Forestry based on air-dry wood density (15% moisture content) will divide wood into five levels (unit: g/c㎥):


      Very small:≤0.350;  small: 0.351-0.550;  middle: 0.551-0.750;  large: 0.751-0.950; great: >0.950.





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