With relative humidity and temperature data from the National Oceanic and Atmospheric Administration, the average equilibrium moisture content for each month of the year was calculated for 262 locations in the United States and 122 locations outside the United States. As an aid for storage of kiln-dried lumber, a graph is presented for determining the reduction in equilibrium moisture content that results from heating air in an enclosed storage space above the temperature of the outside air.

Minimizing wood shrinkage is a priority for many wood products in use, particularly engineered products manufactured to close tolerances, such as wood propellers for unmanned surveillance aircraft used in military operations. Those currently in service in the Middle East are experiencing performance problems as a consequence of wood shrinking during long-term storage at low equilibrium moisture content conditions prior to installation. To evaluate the extent of shrinkage, seven sugar maple (Acer saccharum) veneer propellers were dried from 11% to 3% moisture content in a controlled environment of 150°F (65°C) for 3 days. Two of these wood propellers were encased in polyethylene bags. Results showed 5 to 20 times more shrinkage for the thickness of the propeller hub and the hub face perpendicular to the propeller blades (across the grain), respectively, compared with the hub face parallel to the blades (along the grain). Two hubs, coated with aluminum oxide paint, showed dimensional changes similar to those observed for uncoated hubs. For the two wood propellers encased in polyethylene bags, moisture loss was slowed during the course of the experiment by roughly 46%. Wrapping the wood propellers prior to shipping would slow moisture desorption, thereby minimizing shrinkage during short-term storage. Processing the propellers at a lower equilibrium moisture content would minimize shrinkage during long-term storage.