The Influence of Sapwood-Heartwood Conversion of Bordered Pit Tori In Western Hemlock on Bisulfite Pulping

In an effort to determine why heartwood of western Hemlock [Tsuga heterophylla (Raf.) Sarg.] is difficult to pulp by sulfite technology, ultraviolet (UV) and scanning electron microscopy were used to examine hemlock heartwood and sapwood before and after acid-bisulfite pulping. Resulting data showed that UV-absorbing material that is located in the intertracheid bordered-pit membranes and that is solvent-extractable in the sapwood is suggested to be low molecular weight procyanidins that polymerize into unextractable polymers during heartwood formation. Condensation of these polymers occurs under the strongly acidic conditions of acid bisulfite pulping, reducing wood permeability to cooking liquor

Chemical and Physical Properties of Tumor-Affected Sitka Spruce

The chemical composition, fiber properties, and pulpability of a Sitka spruce (Picea sitchensis) massive trunk and root tumor were compared with normal second-growth wood. In general appearance the tumored tissue looked like normal wood in that it had annual rings and definite sapwood and heartwood zones. However, the trunk tumor showed no visible evidence of compression wood, whereas the trunk of the affected tree above and below the tumor contained about 30% compression wood. The tumor tracheids were short, curved, and twisted; and numerous traumatic resin canals were present. The wood rays and bark showed no apparent abnormalities. Paper prepared from kraft pulp tumor wood was lower in burst, tear, tensile, and opacity, and higher in fold and shrinkage, density and air resistance compared to pulp from the second-growth control. Chemical analysis indicated that the tumor-affected tree had a higher hemicellulose content, primarily as galactan-containing polymers, than the second-growth control. The factor causing the tumor growth was not ascertained in this study