Abstract: A restraining device is used in a dry kiln with a load of green lumber in order to reduce warpage during drying and cooling. A single restraint device is comprised of a pair of inverted leaf springs joined together at their centers and having a strap extending from one end of the top spring about the load of lumber and terminating at the other end of the top spring together with a tensioning device for the strap. Before the load of lumber is placed in the dry kiln, the tensioning device will draw down both the bottom and top leaf springs close to the load where the tensioning device will lock them in place. During drying, as the load shrinks, the top spring will be relaxed while the bottom spring will maintain a force across the width of the load, thereby substantially reducing warp.