Cooling tubes for glass filament production apparatus

In an apparatus for forming glass filaments comprising the combination of:

• a chamber for the containment of molten glass, said chamber having a base, a plurality of small orifices in said base for discharging fine streams of molten glass from said chamber for attenuation into filaments;
• a plurality of cooling means positioned beneath and in proximity to said base, said cooling means being arranged to extend intermediate said orifices to cool glass filaments being drawn from said chamber, wherein said cooling means are each formed as a hollow tube from a base metal clad with a layer of noble metal;
• said base metal being selected from the group consisting of copper, and refractory metals including nickel, Inconel, molybdenum, and alloys of these materials, said hollow cooling tube having a wall thickness within the range of 0.010 to 0.040 inches;
• said noble metal being selected from the group consisting of platinum, palladium, rhodium, iridium, gold, silver, and their alloys, said noble metal cladding layer having a secondary wall thickness within the range from about 0.004 to 0.008 inches.