Kraft pulping of white spruce bole and branch

Abstract

When pulped by the same schedule, barked white spruce (Piceaglauca (Moench.) Voss.) branch wood was comparable in pulp yield to the bole wood. Handsheet made of unbeaten branch pulp showed higher bulk and stretch, comparable tensile and burst strengths, and considerably lower tear strength than bole wood. In the case of beaten pulps, branch pulp gave comparable tensile strength and stretch and lower burst and tear strengths. Inclusion of bark in the cooking increased chemical consumption and degraded sheet cleanliness. Pulping of mixtures containing up to 20% branch wood reduced the tear, burst, and tensile strengths by about 10%). It appeared that the inclusion of branch wood in the furnish within the natural amount limit in kraft pulping would be feasible.