High transmission grey glass composition with reduced iron
A glass composition has a base and a colorant. The composition of the base is 68 to 75% SiO 2 , 10 to 18 wt. % Na 2 O, 5 to 15 wt. % CaO, 0 to 10 wt. % MgO, 0 to 5 wt. % Al 2 O 3 , and 0 to 5 wt. % K 2 O, where CaO+MgO is 6 to 15 wt. % and Na 2 O+K 2 O is 10 to 20 wt. % is provided. The composition of the colorants comprises 0.22 to 0.36 wt. % Fe 2 O 3 , 0.10-0.18 wt. % FeO, 0.1 to 0.5 wt. % MnO 2 , 1.5 to 13 ppm selenium, and 0 to 15 ppm Cobalt. A redox ratio of the weight of FeO to the total weight of iron is in a range of about 0.35 to up to less than about 0.60. The glass has spectral properties at a control thickness of 4.0 mm of 74 -77% transmittance using illuminant A, 57-65% ultraviolet transmittance, 30-46% infrared transmittance and 50-61 % total solar energy transmittance. The color of glass of the invention using illuminant C with a 2° observer is a parallelogram bounded by the following x and y chromaticity coordinates: (0.304, 0.314); (0.3075, 0.3205); (0.3065, 0.323); and (0.303, 0.317). The color space renders the glass color a neutral grey.
1 . A colored glass having a base and a colorant, wherein composition of the colorant by weight of the colored glass comprises:
0.22 to 0.36 wt. % Fe 2 O 3 ;
0.10 to 0.18 wt. % FeO;
0.1 to 0.5 wt. % MnO 2 ;
1.5 to 13 ppm selenium; and
0 to 15 ppm Cobalt;
wherein a redox ratio of the weight of FeO to the total weight of iron is in a range of about 0.35 to up to less than about 0.60; and
wherein the colored glass at 4 mm. control thickness has a light transmittance using illuminant A in a range of 74 to 77%, an ultraviolet transmittance in a range of 57 to 65%, an infrared transmittance in a range of 30 to 46%, a total solar energy transmittance in a range of 50 to 61%, and a color using illuminant C substantially within a parallelogram bounded by chromaticity coordinates (0.304, 0.314), (0.3075, 0.3205), (0.3065, 0.323), and (0.303, 0.317).
2 . The colored glass of claim 1 wherein said redox ratio of the weight of FeO to the total weight of iron is in a range of about 0.45 to about 0.55.
3 . The colored glass of claim 1 wherein the composition of the base by weight of the colored glass includes 1.3 to 1.8 wt. % anthracite coal.
4 . The colored glass of claim 1 wherein the composition of the base by weight of the colored glass includes 1.4 to 2.0 wt. % graphite.
5 . The colored glass of claim 1 wherein the dominant wavelength is in a range of 490.8 to 509.6 nanometers.