Sorting and Stacking are Important Technical Processes that Condition the Lumber Lumber is sorted by thickness and length and then sent to the appropriate size bay. When enough of one size is available the lumber is bundled and sent to the stacker. The stacker takes the bundle and then layers the boards and applies spacer sticks for each 48 inch (121.92 cm) course. The stacked and "stickered" the unit is left sitting for a minimum of three days to set alder's characteristic and very desirable natural golden honey color.