A glass bottle forming system is described in which a main glass melter is connected to a forehearth with a fairly conventional feeder provided at the delivery end of the forehearth. The feeder opening in the bottom of the forehearth is closed by a first orifice member through which a molten core glass will flow. Beneath the first orifice there is positioned a second orifice member that has an orifice that is slightly larger than the orifice in the first orifice member. A small melter contains a glass of essentially the same composition as that in the main melter, but with a coefficient of expansion slightly less than that of the core glass. This lower expansion glass is fed to the second orifice member so that it can flow out of the orifice with the core glass in surrounding relationship with respect thereto. The skin glass melter is connected to the second orifice member by a gravity feed system in which the connection is thermally controlled so that the viscosity of the two glasses are maintained essentially the same. Two embodiments of the skin melter and the second orifice are disclosed. In one embodiment the second orifice is vertically adjustable so as to vary the volume of skin glass flow relative to the core glass flow. The second embodiment has the second orifice supporting an annular bushing that is vertically adjustable and it cooperates with the bottom of the upper orifice member to regulate the flow of glass into surrounding relationship to the core glass coming through the first orifice member.