Twill weave

The second basic weave pattern used in manufacturing fabrics is the twill weave. This weave is characterized by diagonal lines or ribs (twill lines) on the face, and often on the back, of the fabric. The face diagonal can vary from reclining twill, with a low 14-degree angle, to steep twill, with a 75-degree angle. A twill angle of 45-degrees is considered to be medium diagonal or regular twill; it is the most common. The angle of the twill line is determined by the closeness of the warp ends, the number of yarns per inch, the diameters of the yarns used, and the actual progression forming the repeat. These twill lines are produced by letting all warp ends interlace in the same way but displacing the interlacing points of each end by one pick relative to that of the previous end. While the plain weave can only be woven in one form, there exist several options with regard to twill. Twill lines are formed on both sides of cloth. The direction of diagonal lines on the face side of cloth is opposite to that on the wrong side coinciding respectively with the weft and warp floats on the other side. Thus, if warp floats predominate on one side of the cloth, weft floats will predominate in the same proportion on the other side. Twills differ from plain weaves in the increased number of picks and ends needed to complete a repeat pattern. Whereas a plain weave requires two ends and two picks for a repeat, the simplest twill requires three picks and three ends. At least three healed-shafts are needed to make a twill weave. Normally straight drafting system is used to produce regular twill fabric. The smallest possible repeat for a twill weave is 3 ends x 3 picks, and there is no theoretical -upper limit to the size of the repeat.