3.2 Twill weave derivatives

1. 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.

2. 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

3. 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.

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

5. 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

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

7. 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).

8. Fig. 3.13 Compound weaves

9. 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).

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

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

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