The variety of market softwood kraft pulps available globally in terms of strength, bulk and optical properties is significant. Yet by understanding the basic fibre properties length and especially coarseness, it is possible to group pulps according to the region in which their trees were grown. Slow growth regions in the northern hemisphere are dominated by spruce and some pine species and tend to possess very fine fibres consistent with a predominance of spring or earlywood fibres. In very temperate regions where the growing period is longer and forests are faster grown, fibres exhibit thicker cell walls and higher coarseness consistent with a higher content of summer or latewood. And regions affected by the gulf stream exhibit fibres with average coarseness consistent with a growing season between those of northern and southern regions. In terms of pulp tensile strength development, the range of available pulps can be broken down into A, B and C regions corresponding to fibre coarseness – fine northern fibres are A-pulps whereas faster growing southern fibres and C-pulps and Scandinavian fibres fall in between.
Characteristics of common Softwood Reinforcement Pulps
Interactive presentation by Region (requires Adobe Flash)