Improving visual color sorting of dimension stock

Color matching of dimension stock that comprises edge-glued panels is growing in importance due to increased demand for lighter colored, more uniform panels. Such panels are typically matched by visual grading. In this paper, we report on the improvement in uniformity of lightness of white oak panels attained through the implementation of a light or dark visual pre-sort prior to actual matching of the panels. Lightness was measured with a portable color-sensing device (colorimeter) to provide a quantitative measure of color of the visually matched panels. The pre-sorting procedure resulted in panels that had approximately 56 percent of the variation of lightness in panels matched without a pre-sort, as measured by within-panel standard deviation. The pre-sorting procedure required greater time, but the final product could be sold for a higher price. Such changes in procedure may therefore improve product quality in lieu of investment in color measuring devices.