Methods for the production of glass substrate blank

Abstract

Provided are a method for producing a glass suitable for an information recording medium required to have high qualities, a process for the production of a glass substrate blank from the above glass and a process for the production of a glass substrate from the above blank. The method is for the production of a glass containing an alkali metal element by melting a glass material in a glass melting apparatus and uses, as said melting apparatus, a melting apparatus whose glass-contact portion is made of a material containing zirconium and containing substantially no alkali metal element. In the process for the production of a glass substrate blank, the glass obtained by the above method is press-molded or is subjected to a float process, and in the process for the production of a glass substrate, the above glass substrate blank is lapped and polished.

Dependencies are inferred from the claim text.