An apparatus for supporting a workpiece during heat-treating includes a support plate having a non-planar upper surface, and a support system. The support system is configured to support the workpiece above the support plate during heat-treating of the workpiece, such that a lower surface of an initial shape of the workpiece is supported at a non-uniform spacing above the non-planar upper surface of the support plate, said non-uniform spacing including an edge gap beneath an outer perimeter of the workpiece, and a central gap at a central axis of the workpiece.