1. US6408650 - Nitrate/nitrite-free manufacturing of glass with selenium

The invention is a method of retaining selenium in a lass containing selenium by including a manganese compound and not including nitrates or nitrites routinely used in the industry to retain selenium. Particularly, a preferred embodiment involves manufacturing a gray soda-lime-silica glass composition including selenium as a colorant, the components of the gray soda-lime-silica glass have colorants consisting essentially of: greater than 0.9 to 1.9 wt. % total iron oxide as Fe₂O₃; 0.10 to 1.00 wt. % manganese compound as MnO₂; 0.0010 to 0.0060 wt. % selenium as Se; 0.002 to 0.025 wt. % cobalt oxide as Co, and 0 to 1.0 wt. % titanium oxide as TiO₂which are combined and melted to make the glass composition. The glass composition has at 4.0 mm. thickness: 10 to 55% light transmittance using Illuminant A, less than 25% ultra violet transmittance, and less than 50% infra red transmittance.