Neutral gray absorbing glass comprising manganese oxide for selenium retention during processing

A heat absorbing, neutral gray colored glass composition having a base glass composition comprising:

• 71 to 74% SiO.sub.2, 13 to 13.80% Na.sub.2 O, 8.4 to 8.7% CaO, 3.5 to 4% MgO, 0.15 to 0.25% Al.sub.2 O.sub.3, and 0 to 0.1% K.sub.2 O, where CaO + MgO is 6 to 15% and Na.sub.2 O +K.sub.2 O is 10 to 20%, and colorants consisting essentially of:
• 1.20 to 1.60 wt. % total iron oxide as Fe.sub.2 O.sub.3 ;
• 0.0160 to 0.0185 wt. % cobalt as Co;
• 0.0020 to 0.0040 wt % selenium as Se;
• 0.15 to 0.60 wt. % manganese oxide as MnO.sub.2 ;
• and 0.0 to 0.35 wt. % titanium oxide as TiO.sub.2, the glass at 4 mm. control thickness having light transmittance using illuminant A between 16.0% and 20.0%, ultra violet transmittance between 5 and 10%, infra red transmittance between 10 and 18%, and a dominant wavelength between about 470 and 590 nanometers.

A heat absorbing, neutral gray colored glass composition having a base glass composition comprising by weight:

• 68 to 75% SiO.sub.2, 10 to 18% Na.sub.2 O, 5 to 15% CaO, 0 to 10% MgO, 0 to 5% Al.sub.2 O.sub.3, and 0 to 5% K.sub.2 O, where CaO + MgO is 6 to 15% and Na.sub.2 O + K.sub.2 O is 10 to 20%, and colorants consisting essentially of:
• 0.90 to 1.90 wt. % total iron oxide as Fe.sub.2 O.sub.3 ;
• 0.002 to 0.025 wt. % cobalt as Co;
• 0.0010 to 0.0060 wt. % selenium as Se;
• 0.10 to 1.0 wt. % manganese oxide as MnO.sub.2 ;
• and 0.0 to 1.0% titanium oxide as TiO.sub.2 ;
• the glass at 4 mm. control thickness having light transmittance using illuminant A of 10.0% to 55.0%, ultra violet transmittance less than 25.0%, and infra red transmittance is less than about 50.0%;
• and being made from batch materials comprising sand, soda ash, dolomite, limestone, salt cake, rouge, sodium nitrate, a manganese containing compound, carbocite, a cobalt containing compound, and selenium.