In cathode ray tubes, a tension is imposed into the shadow mask during manufacturing to avoid slight variations in the position due to in service temperatures or deformation. Initially, tension is imparted to the shadow mask after it is welded to the compressed mask frame and the frame is allowed to retract. Subsequently, during further processing of the cathode ray tube, the tensioned shadow mask is subjected to heating. The heating causes some of the tension to decrease due to stress relaxation phenomenon associated with heating and creep. In the present study, the tension variation during manufacturing has been analyzed and the appropriate material characteristics and processing conditions to assure a more stable shadow mask for final service are suggested.