The invention relates to a process for manufacturing a glass by melting, at more than 1300° C., batch materials comprising silica and an alkali or alkaline-earth metal sulfate, characterized in that a sulfide is added to the batch materials in order to reduce the height of foam at the surface of the bath of liquid glass at more than 1300° C. The invention reduces the formation of foam at the surface of the glass and improves the heat exchanges between the overhead burners and the glass bath. The invention is particularly suitable for glass intended to be fiberized.