A method for manufacturing an alkali-free glass substrate capable of manufacturing an alkali-free glass substrate having a higher strain point by decreasing the -OH value of the glass is provided. The method for manufacturing an alkali-free glass substrate is a method for continuously manufacturing a SiO.sub.2Al.sub.2O.sub.3RO (RO is one or more of MgO, CaO, BaO, SrO, and ZnO) based alkali-free glass substrate, which includes a step of preparing a raw material batch containing a tin compound and substantially not containing an arsenic compound or an antimony compound, a step of electric melting the prepared raw material batch in a melting furnace capable of conducting electric heating by a molybdenum electrode, and a step of forming the molten glass into a plate shape by a downdraw method.

A glass sheet of the present invention has a content of Li.sub.2O+Na.sub.2O+K.sub.2O of from 0 mol % to less than 1.0 mol % and a content of B.sub.2O.sub.3 of from 0 mol % to less than 2.0 mol % in a glass composition, has a -OH value of less than 0.20/mm, and has a thermal shrinkage ratio of 20 ppm or less when increased in temperature from normal temperature at a rate of 5 C./min, kept at a temperature of 500 C. for 1 hour, and decreased in temperature at a rate of 5 C./min.

A carrier glass of the present invention is a carrier glass for carrying an organic resin substrate, wherein the carrier glass has a flat sheet shape having a thickness of from 0.1 mm to 1.2 mm, wherein the carrier glass has a content of iron in glass in terms of Fe.sub.2O.sub.3 of from 45 ppm by mass to 130 ppm by mass, and wherein the carrier glass has a transmittance at a wavelength of 308 nm in a thickness direction of from 71% to 81%.

A glass substrate of the present invention has a temperature at a viscosity at high temperature of 10.sup.2.5 dPa.Math.s of 1,650 C. or less, and an estimated viscosity Log .sub.500 at 500 C. of 26.0 or more calculated by the equation Log .sub.500=0.167Ps-0.015Ta-0.062Ts-18.5.

In various embodiments, refractory-metal glass melt electrodes are single-crystalline, at least within an outer layer thereof.

In various embodiments, refractory-metal glass melt electrodes are single-crystalline, at least within an outer layer thereof.

Disclosed herein are glass manufacturing methods, the methods including delivering a molten glass to a melting vessel including at least one electrode comprising MoO.sub.3, applying an electric current to the at least one electrode, contacting the batch materials with the at least one electrode for a time period sufficient to reduce an oxidation state of at least one tramp metal present in the batch materials, and melting the batch materials to produce a molten glass. Methods for modifying a glass composition are also disclosed herein, as well as glass articles produced by these methods.

Disclosed herein are glass manufacturing methods, the methods including delivering a molten glass to a melting vessel including at least one electrode comprising MoO.sub.3, applying an electric current to the at least one electrode, contacting the batch materials with the at least one electrode for a time period sufficient to reduce an oxidation state of at least one tramp metal present in the batch materials, and melting the batch materials to produce a molten glass. Methods for modifying a glass composition are also disclosed herein, as well as glass articles produced by these methods.

A technical object of the present invention is to devise an alkali-free glass substrate having high devitrification resistance and high heat resistance. In order to achieve the above-mentioned technical object, the alkali-free glass substrate of the present invention includes as a glass composition, in terms of mol %, 60% to 80% of SiO.sub.2, 8% to 25% of Al.sub.2O.sub.3, 0% to less than 3% of B.sub.2O.sub.3, 0% to less than 1% of Li.sub.2O+Na.sub.2O+K.sub.2O, 0% to 10% of MgO, 1% to 15% of CaO, 0% to 12% of SrO, 0% to 12% of BaO, 0% to less than 0.05% of As.sub.2O.sub.3, and 0% to less than 0.05% of Sb.sub.2O.sub.3, and has a thickness of from 0.05 mm to 0.7 mm, a strain point of 700 C. or more, and a -OH value of less than 0.20/mm.

A technical object of the present invention is to devise an alkali-free glass substrate having high devitrification resistance and high heat resistance. In order to achieve the above-mentioned technical object, the alkali-free glass substrate of the present invention includes as a glass composition, in terms of mol %, 60% to 80% of SiO.sub.2, 8% to 25% of Al.sub.2O.sub.3, 0% to less than 3% of B.sub.2O.sub.3, 0% to less than 1% of Li.sub.2O+Na.sub.2O+K.sub.2O, 0% to 10% of MgO, 1% to 15% of CaO, 0% to 12% of SrO, 0% to 12% of BaO, 0% to less than 0.05% of As.sub.2O.sub.3, and 0% to less than 0.05% of Sb.sub.2O.sub.3, and has a thickness of from 0.05 mm to 0.7 mm, a strain point of 700 C. or more, and a -OH value of less than 0.20/mm.