PURPOSE: To prevent facula type defect by mixing a fine powder additive, which is more reactive with a glass powder than CO2 and capable of preventing the reaction product form generating a decomposition gas in a heat treating and melt sticking temp. region of the glass, with the glass powder.

CONSTITUTION: An alkali-containing glass such as a soda lime based glass containing a CO2 adsorptive and reactive base material such as an alkaline earth ion or alkaline earth metal ion is pulverized to a specific particle size. The fine powder additive composed of an acidic material such as H3BO3, B3O3, anhydrous or hydrate Al2(SO4)3 Sb2O3, As2O3, anhydrous or hydrate Al2(SiO3)3 is more reactive than CO2 with the glass powder in the temp. range ≤softening point of glass and the fine powder additive itself or the reaction product of the glass powder therewith does not generate the decomposition gas in the heat treating and melt sticking temp. range of glass. Next, 0.1-50 milli equivalent ≥1 kind of the fine powder additive having 1/3 times particle diameter of the glass powder is mixed with 100g alkali-containing glass powder and is fired at a specific temp. after press granulating to obtain a glass sintered compact free from facula type defect.