What is the standard for high-end Finnish wood? The appearance grade of Finnish wood is mainly artificially distinguished according to the size of the appearance of the wood and the density of the distribution. According to European standards, the appearance grade of European red pine (Finnish wood) is divided into three levels: A, B, and C. Class A wood is located in the trunk of the tree. This part of the trunk has no branches, so there is no stuttering at all; Class B wood is located in the crown section. There are more branches but most of them are growing branches. The knots that occur are mostly knots. Grade C wood is located between the canopy and the trunk. There are more dead branches here, and there is more dead knot on the appearance of the wood. Kunming's high-end Finnish wood raw material grades are distinguished by the following preferred grades: Grades 1-3 are smaller and less knotted. Due to the increase in the width and thickness of wood, the number and size of corresponding knots are also increased on three sides: Grades 0-3 / 75% jointless on one side Take 100 wooden boards as an example, of which 75 branches are all jointless on one side, and the remaining 25 branches will have 2-5 small knots on all sides: 0-1 / 70% on all sides Section diamond level: There is a maximum of 0-3 stubs on each face, and the stoma size is controlled at 25-6mm, but it does not include stubs below 5mm. SF level: The stoma size is arbitrary, and the basic stoma size is controlled within 4cm. Level, AB level and M level.