These twills are constructed by breaking the continuity of any continuous twill weave. The continuity can be broken in either a regular or an irregular order. Broken twills generally give a stripe-like effect. The direction of the stripes can tend to be in either the direction of warp or weft accordingly as the continuity is broken warp or weft way.
A large variety of attractive effects, generally somewhat similar in appearance to herringbone twills, can be produced by breaking a regular twill. One of the simplest methods of constructing a broken twill is shown in the figure. The method involves skipping a suitable warp thread in a repeat of the twill.
In the figure, A is shown a 1/3 twill with three repeats and the design of the broken twill is shown in Fig. 4.15 B. In the method adopted above, the most suitable number to skip is one less than half the number of threads in the repeat of the twill i.e (N/2 – 1) where N is the number of threads in the repeat of the twill. According to the above formula, the number of threads to miss is 4/2 – 1 = 2 – 1 = 1. Thus in the design, the second end is missed in the first repeat, the third end is missed in the second repeat and the fourth end is missed in the third repeat. It should be remembered that no similar ends must be missed in any two or three repeats.