There is insufficient evidence, however, to conclude that log diameter and external defect dimensions explain a significant amount of variation in adventitious knot depth, bark distortion depth, bark distortion angle, over-grown knot angle, and unsound knot angle.
Of the five defect types sampled, the program will provide internal information for adventitious knot volume, bark distortion volume, overgrown knot volume and depth, sound knot angle and volume, and unsound knot volume.
Due to cost constraints, it was decided to limit the initial investigation to the five most common defect types from the USDA Forest Service log data: Overgrown knots, adventitious knots, sound knots, unsound knots, and bark distortions.
Unsound knot A knot not solid across its face or else softer than the surrounding wood, due to decay of other defects.
Defect data were then collected for any occurrence of splits, wane, shake, holes, rot, decay, unsound knots, bark pockets, and mechanical defects.
However, based on area, the wane/void defect is most important, followed in decreasing order of importance by stain, bark pocket, split, decay, and unsound knots
. As expected, the results in Table 7 establish that the better grades have more clear wood.
No attempt was made to distinguish between sound and unsound knots
. An analysis of variance, performed using the MIXED procedure in SAS software (2002), indicated that no significant difference existed between the four treatment groups (p-value of 0.323, 76 degrees of freedom, standard error of 0.356 MPa).