Abstract: A forehearth supplied with molten glass from a tank furnace, with bottom passages overlying bushings for the extrusion of vitreous filaments, forms an elongate chamber whose sidewalls are penetrated by heating electrodes spaced apart in the longitudinal direction and arrayed in two relatively staggered tiers. The electrodes of the lower tier are more numerous in the vicinity of the bottom passages than between these passages. The heating effect of the electrodes can be supplemented by top burners disposed above the glass level.

Abstract: A forechamber or reservoir to which molten glass is fed, is provided with burners for heating the surface of the glass mass. The molten glass is conducted from the forechamber via at least one opening in its bottom wall into a vertically disposed intermediate chamber which is provided at its lower end with a nozzle heating plate having a plurality of orifices through which the mass is extruded. The intermediate chamber is provided with electrode heating elements so that the glass mass may be heated within the chamber. The height of the chamber is greater than its longitudinal length or diameter so that a laminar flow, caused by the head of the molten glass through the forechamber and intermediate chamber, is effected.