Grading

After the drying, the wood is sorted and cut in exact lengths. This step is called tuning. Sorting is done after many different regulatory frameworks, both visually and mechanically. In Sweden, basic rules for the Visual sort is in the SS a 1611-1, Visual trading sorting of rough sawn timber of coniferous trees (2000), the "Blue book"-Nordic wood, sorting rules for sawn timber of pine and spruce (1994), etc.

Sorting criteria of sawn timber in Europe, vary between sawmills, despite attempts to create uniform rules. One explanation for this is that the properties vary with the sawmill's geographical location.

Grading Classes

Mechanical sort applied to the structural timber products as shall be strength graded. The classes used today are decided and approved within the EU acquis, SS-EN 338 strength classes are used in Sweden: C14, C18, C24, C30, C35. Strength Sorted timber can also be graded visually. Special rules exist for this sorting, which may only be carried out by specially trained personnel. Directly after the sort should be stamped on the wood flat side with T or C followed by the characteristic strength of wood, such as alinea T24 or C24.

When finally adjusting stamped wood with the so-called shipping mark, one can infer the quality of the product.


 
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