Patent ID: 6170292
Filing Date: 2001-01-09
Classification: C03C,Y10S

Abstract:
A method for manufacturing a medium gray glass composition from raw materials 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: total iron oxide as Fe.sub.2 O.sub.3 in an amount greater than 0.5 and less than 0.9%; 0.1 to 1.0% manganese oxide as MnO.sub.2 ; 0.002 to 0.010% cobalt oxide as Co; and 0.0005 to 0.003% selenium; the glass having at a 4.0 mm thickness: 485-570 dominant wavelength, less than 5.0% purity of excitation, less than 40% ultraviolet transmittance measured over 300-400 nm, less than 45% infra red transmittance measured over 760-2120 nm, with 35-58.7% light transmittance using Illuminant A, wherein said method comprises the steps of mixing and melting the raw materials suitable to manufacture the glass composition.