Abstract: A method of manufacturing a picture tube shadow mask wherein a thin metal plate containing iron and nickel as major components is first etched to form a plurality of mask apertures, then, annealing of the metal plate is performed and, after being cooled in a reducing atmosphere, a darkened oxide layer is formed on the surface of the annealed metal plate by subjecting the metal plate at first to a relatively weak oxidizing steam atmosphere and then to a relatively strong oxidizing steam atmosphere.

Abstract: A color cathode picture tube including an envelope having a fluorescent screen therein, a shadow mask assembly having a shadow mask and a mask frame for holding the shadow mask at its peripheral edge, and a shadow mask supporting member for supporting the shadow mask assembly inside the envelope. The shadow mask supporting member comprises a first metal strip having a thermal expansion coefficient substantially equal to that of the mask frame, a second metal strip joined to the first metal strip at one side thereof so that their respective faces may form a continuous face, this second strip having a thermal expansion coefficient higher than that of the first strip, and a third metal strip joined to the first metal strip at the other side thereof so that their respective faces may form a continuous face, the third strip having a thermal expansion coefficient lower than that of the first metal strip.