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A sliver (/ˈslaɪvər/) is a long bundle of fibre that is generally used to spin yarn. A sliver is created by carding or combing the fibre, which is then drawn into long strips where the fibre is parallel.[1] When sliver is drawn further and given a slight twist, it becomes roving.[2][3]
Worsted textiles differ from woolen textiles in that, after carding, they are subjected to gilling, a process to make sure the sliver has a more uniform linear weight, and lubricants are added.[4][5][6]
Gilling is the blending together of card slivers with the direction of feed alternated to make a final sliver suitable for spinning.
The preparative gilling is mainly to align the fibers in a parallel direction, further blend the wool through doubling and to add moisture and lubricants.
The latter is achieved by passing the wool at least once through a special gilling machine which has an auto-levelling device, which continuously detects the linear weight of the slivers being fed into the machine, and speeds up or slows down the machine accordingly.