Abstract: A glass substrate for use as an information recording medium has an average surface roughness (Ra) in the range of 0.3 nm≦Ra<3.0 nm and includes surface irregularities shaped and distributed isotropically and arranged substantially in succession. The surface irregularities include 5 to 50,000 convexities having a height of at least 3 nm and no convexities having a height of at least 15 nm within an area of 50 &mgr;m×50 &mgr;m. A porous region produced by an acid treatment process in the glass substrate would be completely removed if excessively etched by an alkaline solution. However, the etching process using the alkaline solution can be stopped at a stage where the pores in the porous region are enlarged by controlling conditions for the acid and alkali treatment processes.

Abstract: A glass substrate for use as an information recording medium has an average surface roughness (Ra) in the range of 0.3 nm≦Ra<3.0 nm and includes surface irregularities shaped and distributed isotropically and arranged substantially in succession. The surface irregularities include 5 to 50,000 convexities having a height of at least 3 nm and no convexities having a height of at least 15 nm within an area of 50 &mgr;m×50 &mgr;m. A porous region produced by an acid treatment process in the glass substrate would be completely removed if excessively etched by an alkaline solution. However, the etching process using the alkaline solution can be stopped at a stage where the pores in the porous region are enlarged by controlling conditions for the acid and alkali treatment processes.

Abstract: A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.

Abstract: A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.

Abstract: A glass substrate for use as an information recording medium has an average surface roughness (Ra) in the range of 0.3 nm≦Ra<3.0 nm and includes surface irregularities shaped and distributed isotropically and arranged substantially in succession. The surface irregularities include 5 to 50,000 convexities having a height of at least 3 nm and no convexities having a height of at least 15 nm within an area of 50 &mgr;m×50 &mgr;m. A porous region produced by an acid treatment process in the glass substrate would be completely removed if excesively etched by an alkaline solution. However, the etching process using the alkaline solution can be stopped at a stage where the pores in the porous region are enlarged by controlling conditions for the acid and alkali treatment processes.

Abstract: A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.

Abstract: A heat-radiation reflective glass comprising a glass plate and a film formed on the glass plate. The film has composition comprising 65 to 96% by weight of cobalt, 2 to 25% by weight of chromium and 2 to 33% by weight of iron based on the total metal weight per unit area, and has a layer thickness of 10 nm to 70 nm.

Abstract: A coated glass (1) comprising a base glass (3) and provided on at least one side thereof a film (2) formed of an oxide of Sn, and oxide of Sb and an oxide of Ti. The glass has characteristics especially suited for buildings.