Differentiating timber to optimize the pulping process

Large variations in important pulping properties have been demonstrated for wood from trees, not only of different genera, but also between species wi thin a genus, and between their provenances, families and even the individu al clones within families. Tree breeders, who in general have been among th e leaders in measuring this variation have shown that much of it is under g enetic control but site and growth factors affect expression. Some of these properties such as pulp yield, rate of delignification, alkal i consumption and residual unbleached pulp brightness have strong financial implications on the profitability of processing. The industry has been slo w in becoming sufficiently flexible and adapting processes to take advantag e of this variation to optimize financial return from the furnish. A way needs to be found to compensate the wood grower for successfully grow n, bred or genetically modified superior pulping material. The processor th en needs to find a way to adjust the process to match the properties of the se materials to best advantage. Both interests call for the development of a rapid evaluation technique at the mill gate or in loading the digester, a nd near infrared spectroscopy (NIRA) is suggested as a possible way forward . Harvest scheduling, woodyard management and ways of directing batches of timber with predictable properties to the digester in an ordered manner to minimize within-batch variability are lesser challenges that will surely fo llow.