Monday, May 6, 2013

Weaving Basics 03

Twill weave:
Interlace – the place where one yarn intersects another yarn by crossing over it or by going under it (depending on which way you look at the fabric).

Float – The section of a weft yarn that goes over more than one warp yarn (or the section of a warp yarn that goes over more than weft yarn).

The characteristic of a twill weave is diagonal lines woven into the fabric. There are many ways to weave diagonal lines but the most common weave is a 2 x 1 (two by one) weave. (Diagram 7) The twill weave is woven in a pattern that creates diagonal lines by having interlaces run diagonally in the weaving pattern. The pattern can run up to the right (a right hand twill) or up to the left (a left hand twill). As an example a woven herringbone pattern alternates between a right hand twill weave and a left hand twill weave.

Diagram 7: Drawing of a twill weave

Notice that the weft (white) yarns go under two and over one and that the interlaces (the exposed white weft yarns crossing over the warp yarns) are in a diagonal pattern moving up to the right (this is a right hand twill pattern).

In order to weave a basic 2 x 1 twill weave the loom must have a minimum of three harnesses that lift in a specific order. The weaving pattern is complete after three weft yarns are inserted and then starts over again. In a twill weave the weft yarns are not interlaced with every other warp yarn, which creates a float.
Because of the floats the twill weave allows more of the same size yarns to be woven in a square unit (e.g. square inch, square centimeter) than in a plain weave. Using the same size yarns a twill weave thus, would have more yarns per square unit and be heavier than a plain weave fabric.
Twill weaves can come in many different constructions such as 3 x 1, 4 x 1, 3 x 2, or 4 x 2 (there are others – these are just examples).
The characteristic of all twill weaves is the diagonal lines woven into the fabric called twill lines.
Twill weaves are known for their strength and durability. The most common twill weave is denim. Fabrics woven with a twill weave are stronger, heavier, and more durable than those using the same yarns sizes woven with a plain weave.

 

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