Abstract: A flow block and bushing assembly employing an orifice plate having a perforated drawing area with a planar undersurface against which bulk gas flow is directed for cooling and fiber attenuation purposes. The flow block is comprised of an interior layer of highly glass corrosion resistant material, such as zircon, and an exterior layer of highly thermal shock-resistant material. A flow passage extends through both of said layers and is lined with platinum foil. The bushing assembly is removably secured beneath the flow block and comprises a body of refractory material having a flow chamber extending therethrough in alignment with the flow passage. The flow chamber is lined with a platinum foil lining and the orifice plate is joined to the lining and extends over the lower end of the chamber.