Method of making a polarizing glass

A method for producing a polarizing glass article that exhibits a broad band of contrast in the infrared region of the electromagnetic spectrum, and a maximum transmission of greater than 80 percent, the method comprising:

• a) melting a batch for a glass containing a source of silver, copper, or copper-cadmium and at least one halogen other than fluorine or a combination thereof;
• b) forming a glass article from the melt;
• c) subjecting the glass article to a temperature of greater than 76° C. above the softening point of the glass to form and precipitate silver, copper, or cadmium halide crystals in the glass, the crystals ranging in size between about 200-5000 Å;
• d) applying a stress of not over about 2675 psi to the glass article while the glass is at a temperature above the strain point of the glass to elongate the glass article and the halide crystals therein;
• e) exposing the elongated glass article to a reducing atmosphere at a temperature above about 250° C., but no higher than about 25° C. above the glass annealing point, to reduce at least a portion of the elongated halide crystals in a surface layer on the glass article to metal particles.