An investigation of the relationships between harvest season, log age, and drying schedule on the coloration of hard maple lumber

The preferred color of kiln-dried hard maple is bright white. Because of the importance of being able to consistently produce acceptable color, the objectives of this study were to quantify, order, and determine the respective importance of drying schedule, harvest season, and log age on the color of kiln-dried hard maple boards. Trees were harvested in the winter, spring, and summer. For each harvest season 1-inch boards were sawn from freshly cut logs, logs stored for four weeks, and logs stored for eight weeks. Logs not freshly sawn were end coated with a commercial wax emulsion sealer. Drying schedules that produce "normal orange-yellow" (T8-C3) and "white" (T3-C5) colored hard maple were used to dry the boards. A small number of boards were also air-dried. Determination of lumber color, for comparisons between harvest season, log age, and drying schedule, was done with a spectrophotometer. Results illustrated that drying schedule was a much more important factor in determining wood color than log age or harvest season. Differences in color between the treatment groups became most noticeable and uniform after the top 1/32-inch was surfaced from the boards. Results also showed that industry acceptable white hard maple can be produced from logs stored up to eight weeks during the winter, spring, and summer seasons by using a low temperature and humidity drying schedule.