The Effect of Pulping Upon the Dimensions of Wood Tracheids


  • A. M. Scallan
  • H. V. Green


Picea glauca, Pseudotsuga menziesii, Larix decidua, fiber dimensions, cell-wall thickness, fiber diameter, fiber length, soda pulping, yield, bulk density, wood, cross section


The dimensions of the fibres in oven-dry blocks of wood from three species (white spruce, Douglas-fir, and larch) were deduced from measurements of bulk density and the number of fibres per unit cross-sectional area. The blocks were then cooked by the soda process to various yields, and the fibre dimensions were redetermined after the blocks had been washed and oven-dried.

The weight of the fibres per unit length decreased almost in proportion to the yield loss, being reduced at 40% yield to 42% of its value in wood. This finding indicates that the fibres were shortened to only a small extent by pulping (ca. 4% at 40% yield) and that the major changes were in the transverse dimensions of the fibres. At 40% yield, cell-wall thickness and fibre width were respectively reduced to 52.5% and 84% of their original values. The results were independent of wood species.

The changes in the dimensions of the fibres are in keeping with current concepts of the structure of the cell wall.


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