Method of coating fibers

A method of coating mineral fibers formed from a molten material, the fibers moving at a speed of at least 1000 feet per minute from a hot, fiberizing bushing, with a liquid sizing in a forming room containing one or more choppers comprising bringing the moving fibers into contact with or near contact with a continuously moving working surface of a fiber coating element, the element comprising a continuously moving working surface of a sizing applicator located in a fiber forming room containing a plurality of hot bushings and in a location where heat from the bushings cause at least portions of the applicator to operate at a temperature above the temperature of the forming room, and supplying said sizing to the applicator comprising the steps of;

• a) filtering said sizing to remove any foreign object having a dimension greater than
• 13 microns prior to the sizing reaching said working surface of the fiber coating element,
• b) distributing the filtered sizing across the continuously moving working surface of the fiber coating element,
• c) removing, with a physical member, unused sizing and foreign objects from the continuously moving working surface of the fiber coating element downstream of a location where the fibers contact or nearly contact the continuously moving working surface and upstream of the location where the filtered sizing is distributed onto the continuously moving working surface,
• d) removing the unused sizing and foreign objects from the applicator and from an area where the unused sizing is likely to be heated up by radiant and convection heat from the hot bushings such that the unused sizing is not contained in said heated area, an area where the unused sizing will be heated sufficiently to cause the unused sizing to degrade and to form higher viscosity and/or globules, not allowing the unused sizing to remain in said heated area for a time longer than about 300 seconds, and
• e) transporting said removed unused sizing and foreign objects in a return line to a cooler area where said filtering step is accomplished.