The purpose of this study is to investigate and record the principal problems associated with chipped surface quality at canter lines and evaluate degrade and value losses due to these problems.
Mill measurements were conducted in five member sawmills in British Columbia to evaluate the value losses and lumber degrades due to chipped surface defects. The test lumber was sampled from the planing mills to identify the chipping losses and main problems. The five types of chipped surface defects influencing lumber grade are: knot tear-out; failure to remove chipped spline channel; torn grain without knots; scalloping; and chipped thin end.
Average value losses for all mills were $11.4/MBF and $12.6/MBF in freezing and non-freezing conditions respectively. Removing the non-freezing data from one mill changed this to $11.4/MBF and $9.0/MBF respectively. Knot tear out caused 60% of lumber to be degraded. On average, over 55% of knots had tear-out. 42.3% of trim length was caused by failure to remove chipped spline channel.