Process for melting and / or refining glass,
glass ceramic or glass that can be ceramized into
glass ceramic, comprising the steps - Providing a mixture of raw materials, - heating the mixture until a melt is obtained, the mixture being heated at least in sections to a temperature above T3, which corresponds to a
viscosity of the
molten glass of 10 3 dPa*s corresponds to - refining the melt, whereby the melt is heated at least in sections to a temperature above T2.5, which corresponds to a
viscosity of the
molten glass of 10 2,5 dPa*s, and - Obtaining a refined glass, a refined glass-
ceramic or a refined glass that can be ceramized into glass-
ceramic, wherein at least one refining agent of the formula X n O m , where n = 1 or 2, where m = 2 or 5, where X = As, Sb, Sn, or Ce, and / or of the formula Mn SO4, where n = 1 or 2, and M = Na, K, Li, Mg, Ca, Sr, Ba and / or Zn, is used at a concentration of 2 wt% or less, based on the total
mass of the mixture of raw materials, wherein the refining agent has the thermodynamic property that, in a melt of the same composition as the melt in the refining step, at an
oxygen partial pressure p(O2) of 1 bar and a temperature T2, it has at least 30% conversion from a higher to a lower
oxidation state, in particular according to the reaction of X n O m → X n O m-1 + 1 / 2 O2 and / or X n O m → X n O m-2 + O2, and / or according to the reaction of M n SO4 → M n O + SO2 + 1 / 2 O2, where the temperature T2 corresponds to a
viscosity of the
molten glass of 10 2 dPa*s corresponds to with the step of setting an
oxygen partial pressure p(O2) during the refining of the melt, which is reduced by at least 60%, preferably at least 70%, based on the O2 saturation in the melt at the temperature T3.