Abstract: A horizontal type vulcanizer for continuous production of an elongated member made of a natural or synthetic polymer. The elongated member passes through a pressurized liquid heat medium to achieve vulcanization. Leakage from the liquid bath seal is prevented by having an intermediate separation portion and balancing the pressure in the bath with that in the intermediate portion. Thermal deterioration of the seal is prevented by cooling the liquid bath in the region adjacent the seals to increase the viscosity of the bath in that region. A water jacket positioned in contact with the front face of the extruder head prevents scorching of the elongated member prior to vulcanization.