Patent ID: 8464558

Claim:
A process for manufacturing red glass comprising copper, the process comprising: (1) obtaining within a glass melting furnace a mass of colorless molten glass formed by melting at least one batch material comprising sand, wherein said mass is free of sulfides, a weight content of iron oxide in said mass is between 0.01 and 0.15%, and a ratio of the weight of sulfate (in SO 3 form) of said mass to the weight of sand is between 0.3 and 0.6%; (2) conveying said mass of colorless molten glass, having a partial pressure of oxygen of between 10 −7 and 10 −4 , in a feeder channel; then (3) adding within the feeder channel copper oxide and tin oxide to said mass of colorless molten glass to form a copper-containing molten glass, such that a partial pressure of oxygen in said mass of colorless molten glass within the feeder channel is between 10 −7 and 10 −4 ; (4) forming a glass object from said copper-containing molten glass; then (5) heat treating said glass object to develop a red tint and to form a red glass object.