A low infrared absorbing lithium glass includes FeO in the range of 0.0005-0.015 wt %, more preferably 0.001-0.010 wt %, and a redox ratio in the range of 0.005-0.15, more preferably in the range of 0.005-010. The glass can be chemically tempered and used to provide a ballistic viewing cover for night vision goggles or scope. A method is provided to change a glass making process from making a high infrared absorbing lithium glass having FeO in the range of 0.02 to 0.04 wt % and a redox ratio in the range of 0.2 to 0.4 to the low infrared absorbing lithium glass by adding additional oxidizers to the batch materials. A second method is provided to change a glass making process from making a low infrared absorbing lithium glass to the high infrared absorbing lithium glass by adding additional reducers to the batch material. In one embodiment of the invention the oxidizer is CeO.sub.2. An embodiment of the invention covers a glass made according to the method.

A method for producing a glass article having a compressive stress zone close to the surface by redrawing a preform having a rectangular cross section is provided. The preform includes at least a first and a second glass, wherein both glasses are not connected to each other in the preform in a force-fitting manner. The second glass has a higher thermal expansion coefficient than the first glass and is located in the preform in the interior of the glass tube of the first glass. A glass laminate having increased strength is also provided, which is composed as an at least three-layer composite material of at least two different glasses. The individual layers of the layer composite are connected to each other over the entire area and in a non-positive manner, in particular by melting, and the glass laminate has a thermally stable compressive stress zone in the areas close to the surface of the layer composite and a tensile stress zone in the inner region of the layer composite.

A method for producing bubble-free glasses is provided, in which a glass mixture that is arsenic-free, antimony-free and tin-free with the exception of any unavoidable raw material impurities and at least one sulfate compound as a refining agent are used. The glass mixture and refining agent are melted and primarily refined in a first region of a melting tank, an average melting temperature (T1) is set at T1>1580 C. and an average melt residence time (t1) is set at t1>2 hours. A secondary refinement is carried out in a second region, an average melting temperature (T2) is set at T2>1660 C. and an average melt residence time (t2) is set at t2>1 hour, and the proportion of the SO.sub.3 resulting from decomposition of the sulfate is reduced to less than 0.002 wt. %.

A low infrared absorbing lithium glass includes FeO in the range of 0.0005-0.015 wt %, more preferably 0.001-0.010 wt %, and a redox ratio in the range of 0.005-0.15, more preferably in the range of 0.005-010. The glass can be chemically tempered and used to provide a ballistic viewing cover for night vision goggles or scope. A method is provided to change a glass making process from making a high infrared absorbing lithium glass having FeO in the range of 0.02 to 0.04 wt % and a redox ratio in the range of 0.2 to 0.4 to the low infrared absorbing lithium glass by adding additional oxidizers to the batch materials. A second method is provided to change a glass making process from making a low infrared absorbing lithium glass to the high infrared absorbing lithium glass by adding additional reducers to the batch material. In one embodiment of the invention the oxidizer is CeO.sub.2. An embodiment of the invention covers a glass made according to the method.

Titanium oxide containing borosilicate glasses, which have been produced without the use of arsenic and antimony compounds, are provided. An environmentally friendly refining method for providing titanium oxide containing borosilicate glass is also provided. The method includes using oxygen containing selenium compounds as refining agents to provide glasses with good transmittance values in the infrared range and show no disturbing discolorations. The glasses of the present disclosure are particularly suitable for the production of IR light conductors, cover glasses for photo sensors, and UV filters.

In order to provide a method which can produce red glass vessels and which is attended by low cost in respect of the raw materials/starting materials and also in respect of control of process parameters, an appropriate method for producing red glass vessels is proposed in which a colourless molten glass composition containing at most 3% by mass of tin oxide and at most 3% by mass of copper oxide is produced, where the resultant colourless molten glass composition is refined under neutral conditions with sodium sulphate and/or calcium sulphate and with a carbon-containing reducing agent with a molar carbon/sulphate ratio of from 0.5 to 5, where glass vessels are moulded from said refined glass composition, and where the glass vessels are cooled to a temperature of below 520 degrees C. to 580 degrees C.

The present invention relates to a float glass substrate including an alkali-free glass, the float glass substrate having a Cl content of from 0.10 to 0.50 mass %, containing substantially no SnO.sub.2, and having a Pt content of, by mass, from 0.001 to 0.30 ppm. The float glass substrate may have a Rh content of, by mass, from 0.001 to 0.50 ppm.

In a melting step (S1) of generating a molten glass (Gm) by heating and melting glass raw materials (Gr) corresponding to raw materials for a glass article in a melting furnace (10), the glass raw materials (Gr) are heated and molten through combustion of fuel (FH) containing hydrogen, and a water vapor partial pressure (Pp) in the melting furnace (10) is set to 80% or less of a total atmospheric pressure (Pt).

A method for producing a glass ceramic includes: providing a batch of raw materials; heating the batch of raw materials until a melt is obtained, the batch of raw materials being heated at least in a plurality of sections to a temperature above T3 which corresponds to a viscosity of a molten glass of 10.sup.3 dPa*s; refining the melt, the melt being heated at least in a plurality of sections to a temperature above T2.5 which corresponds to a viscosity of the molten glass of 10.sup.2.5 dPa*s; obtaining a refined glass which is configured for being ceramized to form a glass ceramic material; and ceramizing a glass which is configured for being ceramized to form the glass ceramic material, at least one of the step of heating until the melt is obtained and the step of refining being performed with heating by way of H.sub.2 and O.sub.2 combustion.

A method for melting and/or refining glass, glass ceramic or glass which can be ceramized to form glass ceramic includes: providing a batch of raw materials; heating the batch until a melt of molten glass is obtained, the batch being heated at least in sections to a temperature above T3 which corresponds to a viscosity of the molten glass of 10.sup.3 dPa*s; refining the melt, the melt being heated at least in sections to a temperature above T2.5 which corresponds to a viscosity of the molten glass of 10.sup.2.5 dPa*s, refining of the melt includes adjusting an oxygen partial pressure p(O.sub.2) which is reduced by at least 60% relative to an O.sub.2 saturation in the melt at temperature T3; and obtaining a re-fined glass, a refined glass ceramic or a refined glass which can be ceramized to form glass ceramic.