Quantitative assessment of mechanical fibre dimensions during defibration and fibre development

Tree samples from Norway spruce (Picea abies L. karst.) and Scots pine (Pin us silvestris) were refined in a pilot plant trial at equal conditions. Lat ewood fibres got a larger reduction in wall thickness during refining than earlywood fibres. Most oft he split fibres were earlywood fibres, and most fibre splitting occurred during the 1st refining stage. Trees with compact fibres were found to give pulps with small shives content. Using thin-walle d fibres as raw material was found to have a larger impact on surface smoot hness than increased specific energy consumption on originally thick-walled fibres. Keeping all other parameters constant a reduction in wall thicknes s or an increase in fibre splitting caused a considerable reduction of surf ace roughness and increase of light-scattering coefficient.