Patent ID: 8082760

Claim:
A method of making a man-made vitreous (MMV) fibre product comprising fibers of a core layer between fibers of adjacent layers and comprising fiberising a mineral melt using a spinner comprising one or more fiberising rotors which rotate about a substantially horizontal axis, and entraining fibres in air traveling substantially horizontally as a cloud of fibres, collecting the fibres from the cloud as a web on a permeable collector which travels continuously along a path comprising, in sequence, an initial collecting zone, an intermediate collecting zone and a final collecting zone whereby the fibres of the core layer are collected on the collector in the intermediate collecting zone and the fibres of the adjacent layers are collected on the collector in the initial and final collecting zones, and forming the MMV fibre product from the web, characterized in that the core layer comprises MMV fibres mixed with dense particulate additive and the adjacent layers comprise MMV fibres optionally mixed with the dense particulate additive in an amount which is substantially less than in the core layer, and wherein the dense particulate additive is directed downwardly through the cloud of fibres as a region of downwardly directed particles which extends, at the surface of the web, across the width of the web and in the length direction substantially only in the intermediate collecting zone.