Abstract: This invention relates to a method and apparatus for forming a glass container by a press-and-blow system wherein the glass container is provided with a reinforced inner surface. According to the inventive method, fuel gas or a gaseous boron or silicon compound is burnt or otherwise reacted inside a parison after the parison molded in the blank mold is transferred to the finish mold. The burning or other reaction of the fuel gas or gaseous boron or silicon compounds can be carried out just prior to the final blow-molding step in which the parison is blow molded into its final shape, simultaneous with the final blow-molding step, or just after the final blow-molding step. The apparatus of the present invention includes a finish mold provided with a blow head which includes a low selector valve. The low selector valve is open during combustion or other reaction within the parison and is automatically closed during the final blow-molding step by the pressure of the compressed air used in the final blow-molding.