National quality standards and inspection methods vary widely, and are mainly divided into two categories:
(1) Graded quality: The various defects existing in the log itself are classified according to different types of defects, the size of the defect size and the severity of the defects. Generally, they are divided into three to five grades, and the countries using the grade quality standards have China, Russia and other countries. Quality standards and testing methods are generally divided into ten categories: knots, discoloration, decay, insects, cracks, trunk shape defects, wood structure defects, scars (damage), wood processing defects, deformation defects, and so on. (2) Defective quality: The different types of quality defects existing in the log itself are deducted from the original wood length or diameter according to the size of the defect size. Finally, the volume of each log is deducted from the defect size. Volume, individual serious defects can also be combined with lower quality grades. Countries using defective buckle quality are in the United States, Canada and other countries.
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