Spruce Wood Fiber Properties and Mechanical Pulps, 1991 Pulping Conference Proceedings

The value of the wood raw material at the millyard is affected by delivery costs, the quality of wood procurement service and the quality of wood delivered. For wood procurement management, the economic importance of these factors must be recognized. This paper looks at properties of spruce wood fibers as potential wood quality parameters for mechanical pulping. The variation in fiber properties of wood and a few phenomena possibly usable in controlling the fiber properties are being presented. Among these phenomena the most essential ones are the juvenile wood, the proportions of earlywood and latewood fibers and the appearance of knots and reaction wood.

Hypotheses are created theoretically, and they are tested and quantified using empiric secondary material. Because of the basic differences in wood properties between northern spruce and southern pine species, the material is restricted to northern spruces and partly to Radiata pine. It is likely that mature wood in relation to juvenile wood and latewood in relation to earlywood tend to produce pulp of high specific surface in relation to particle size. Thus in specified freeness they are stronger but they have a poorer light-scattering power. To reach a specified light-scattering power, they have to be refined to a lower freeness. The strength properties are likely to remain higher at the expence of somewhat higher specific energy consumption. Reaction wood and especially knotwood are likely to propagate linting of pulp.