Analysis of information sources in references of the Wikipedia article "Sliver (textiles)" in English language version.
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.