3.2 Twill weave derivatives Variations of twill weaves are many. Twill weave can be modified by extending the floats, changing the shift or both. It has a great potential for the introduction of ornamentation into the fabric.

3.2.1 Reinforced twill 1. concept: Reinforced twill weave is the simplest twill weave derivatives, which can be constructed by adding warp or weft marks beside the original ones. See Fig. 3.11. A B C Fig. 3.11 reinforced twill

The reinforced twill is denoted by fraction The reinforced twill is denoted by fraction. The numerator indicates warp overlaps; and the denominator indicates weft overlaps. The direction of the diagonal line is denoted by arrowhead. e.g. ↗at Fig. A, ↗at Fig. B, ↖at Fig. C.

2. Weave drawn Drawing reinforced twill diagram is quite similar to fundamental twill.

3. Weaving plan Straight draft is considered first. Skip draft is chosen where the warp density is too high. See Fig. 3.12. Fig.3.12 skip draft for reinforced twill

4. Applications Reinforced weaves are widely used in varied fabrics, such as serge, gabardine, drill, and are also used in selvedges of other fabrics.

3.2.2 Compound twills 1. concept: The compound twill is obtained by constructing two or more parallel twill lines in the same area. It has a fancy diagonal appearance. The compound twill is denoted by fraction. The numerators indicate warp overlaps; and the denominators indicate weft overlaps. The direction of the diagonal line is denoted by arrowhead. See Fig. 3.13 :(A), (B), (C).

Fig. 3.13 Compound weaves

2. Weave drawing Drawing compound twills are as following steps: 1) Calculating the repeat R: Ro = Ry = numerator +denominator. 2) Drawing the first end according to the fraction given. 3) Drawing the other ends based on the first one and shift (where shift is ±1).

3. Weaving plan ■ Straight draft if often employed to weave compound twill Example ↗ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

4. Applications Compound twills are widely used in fancy fabrics due to its interesting appearance. A compound twill sample:

Home works: 1. Drawing the following reinforced twill weaves. 2/3↗, 4/3↖, 3/5↗, 4/4↖ 2. Drawing the following compound twill weaves. ↗, ↖, ↖, ↗, ↗, ↗.