Abstract: A method of heat and pressure bonding plates of heat conductive metal onto stainless steel bottom surfaces of containers by placing the plates of heat conductive metal of no greater area than the stainless steel surface to be covered into position on the stainless steel surface area, heating the assembly to near the fusion temperature of the heat conductive metal immediately whereafter while the assembly is still at said temperature applying bonding pressure to the assembly. During the pressure bonding, the perimeter of the heat conductive metal plate is confined against spreading to assure uniformity of pressure application and bonding efficiency throughout the laminar area of the assembly and to utilize a die cavity to confine an edge of the plate material thus maintaining the diameter of theedge of the plate.