Abstract: A method and an apparatus for producing a slub yarn from a filament yarn, in which the starting yarn is propelled by an air stream at a first rate and made to impinge on a liquid (water) surface, whereby the yarn is opened to individual single filaments which entangle and fold with each other to form a thicker portion in the yarn body, while being held in a slack condition in the water and finally withdrawn therefrom at a second rate lower than the first rate. The water is preferably whirled to form a vortex. Interlacing of the yarn after withdrawal from the water is also preferable to strengthen the yarn structure.

Abstract: A slub yarn, in which a sheath component is wound around a core component to form a plurality of slub portions along the axis of the yarn, which structure is obtained by simultaneously false-twist texturing the core and sheath components. The slub yarn has a feature that the slub portion includes a multilayered winding structure of seven or more layers of the sheath component wound around the core component. A method for producing the slub yarn includes a step of overfeeding a sheath component to a core component in the direction substantially perpendicular to a passage of the core component in a twisting zone of a false-twist texturing machine while the sheath component is guided by a guide repeatedly traversed along a passage of the core component, a distance between the guide and the passage of the core component being kept in a range not shorter than 10 cm. An apparatus for randomly traversing the sheath component along the core component during the false-twist texturing process is also provided.