//Woven fabrics//

Woven fabrics

The fabric consists of two thread systems. The longitudinal thread system is called warp the one running in transverse direction is called weft. Warp and weft are at a 90° angle to each other. The warp is wound on the warp beam of the loom, whereas the weft is inserted through the shuttle. Warp and weft threads are interlaced according to certain rules, thus creating the thread composite or fabric.

The type of interlacing of warp and weft is called the weave. The order of interlacing is repeated in the weave after a certain number of warp and weft threads. These repetitions are called weave repeat. Accordingly, the repetition of the warp threads is called warp repeat; that of the weft threads, weft repeat.

In the loom, the warp is taut and in a horizontal position. Every thread runs through the heddle, which is fastened to a shaft. The vertical movement of the shafts creates the shed in which the weft is inserted. After being inserted, the weft is pushed against the already woven fabric by the reed.

Each of the differently binding threads in the binding system gets a specific shaft. The number of shafts is limited by the type of weaving machine and the size of the respective dobby. Modern weaving machines usually do not work with more than 16 shafts, due to the high strain on the material on high-speed machines.

Weaves with more than 16 different binding threads are usually woven on a Jacquard machine. This system, invented by the Frenchman Jacquard, allows the raising and lowering of individual warp threads in any order desired. Thereby making it possible to weave complicated large-repeat patterns.

Warp thread count, weft thread count and yarn count in accordance with the weave is called the setting of the fabric. These factors are in a more or less fixed ratio to each other in every fabric. The setting determines the structure of the fabric and indicates the number of warp and weft threads in a certain gauge (e.g. per cm or 10 cm or over the fabric width).

Floating is the position of the warp or weft thread resting on the surface of the fabric and not covered by the other thread system. In the short floating weave the fabric takes up fewer threads, the thread counts of warp and weft are lower. Accordingly, the fabric is lighter in weight, has a thinner cross section and a firmer yarn layer. In the long floating weave, the fabric takes up more threads, the warp and weft thread counts are higher. The fabric is heavier, has a denser cross section and potentially a looser yarn layer. The weaves are divided into three main groups:

Maingroups of bonds

1. WEAVE

The smallest weave is the linen weave, well-known in the wool industry. In the first weft, every 1st, 3rd, 5th, etc. thread is raised and every 2nd, 4th, 6th, etc. is lowered. In the second weft it is the other way round. Thus, the linen weave has the smallest repeat, because it repeats itself in warp and weft after two threads. Both fabric sides show the same amount of warp and weft.

Because the warp threads change with every weft, this interlacing is the harshest when compared to all other weaves. The result is a firm fabric with a smooth surface. The fabric has a thinner cross section and is more porous due to the type of interlacing.

2. TWILL

The distinctive feature of the twills are the diagonally running twill lines. When warp and weft density are the same, this line runs at a of 45° angle. If a thread system is set more tightly, the twill line slants further in the direction of the more tightly set thread system.

With higher warp density the twill line is steeper; with higher weft density it is less slanted. The more the thread densities differ from each other, the more the twill line deviates from the 45° slant. The twill can run from the lower left to the upper right, = right twill = z-twill or from the lower right to the upper left, = left twill = s-twill. The first type is the most common.

Classification of the most important twill weaves:

• UNEVEN-SIDED TWILL // Both fabric sides show different amounts of warp and weft effects. The twill lines on both sides differ from each other. They can have single or multiple twill.

• FINE TWILL twill // The twill line is only one thread thick. If the weave repeat is dominated by the warp, it is called warp twill. If it is dominated by the weft, it is called weft twill.

• HEAVY TWILL // The heavy twill lines are several threads thick. The twill line is distinctive. If the warp dominates on the face side, it is called warp-faced twill. If the proportion of weft predominates, it is called weft-faced twill.

• EVEN-SIDED OR DOUBLE TWILL Even // Warp and weft effect are the same on both sides. Reverse and face side show the same twill pattern. The only difference is that the twill line on the reverse side runs in the opposite direction of the face side. An additional distinction is made between single twill weave and multiple twill weave.

• WEFT REP // Is created by even multiplying of the binding points of the linen weave in the weft direction. This is done by weaving several consecutive warp threads the same way, so that the warp is enclosed by the weft. Vertical ribs appear, explaining the name "vertical rep".

3. ATLAS AND SATIN WEAVE

Atlas weaves create fabrics with a smooth surface. The fabric shows no or only faint twill lines. This is achieved by crossing the threads as little as possible, i.e. every warp or weft thread only has one binding point, thus making the floats relatively long.

The binding points are also evenly spread across the entire weave repeat, so that they cannot touch like twill. This results in the face side being made either almost entirely by the warp or almost entirely by the weft.

PANAMA // If the binding points of the linen weave are doubled in the warp as well as the weft, a cube-like weave is created: the panama.

REP // Rep describes fabrics with a ribbed appearance. Both fabric sides either show only warp or weft, according to the setting. The weave is created from doubling or multiplying the binding points in linen weave in only one direction, either only in the warp or only the weft direction.

WARM REP // Warp rep is created by even multiplying of the binding points of the linen weave in the warp direction. Several consecutive weft threads are woven the same way, so the weft is enclosed by the warp. Horizontal ribs appear, explaining the name "horizontal rep".

Differentiation of Warp and Weft Direction

Fabric Sides, Warp and Weft

Often it is difficult even for experts to recognise which is the face side or which is warp and weft. However, there are indications that can help.

Distinguishing face from reverse fabric side
In principle, the face side is the more valuable and more beautifully finished side. In the case of smooth fabrics with pileless finishings, the face side is always clearly and particularly deeply shorn out.

Many fabrics can be recognised simply by the course of the twill of the weave, which generally runs from the bottom left to the top right (see Weaves). Examples of this are gabardine and tricot. If fancy yarns are used, these are visible primarily on the face side of the fabric. All fabric-type-defining finishes are always on the face side, e.g. in unfulled woollen cloth, velour, loden, broadcloth, etc.

Raising effects that do not show an even and pleasant fabric appearance generally indicate the reverse side. This type of finish is meant to give the fabric more volume or to "break" it, i.e. to make it softer and more pleasing in drape and feel.

In the case of reinforced fabrics, i.e. fabrics with lower warp or lower weft, which get an additional thread system in order to increase their weight, these lower warp or lower weft threads on the reverse side generally exhibit a coarser yarn count and longer weave float.

The holes created on the selvedge by the tenter or drying frame are raised on the face side.

Reinforced fabric

Lower warp
The lower warp is a second thread system running in warp direction under the fabric that is to be reinforced. The lower warp threads are connected to the outer fabric by binding points. However, this cannot change the appearance of the face side.

Lower weft
The lower weft is a second thread system running in weft direction under the fabric that is to be reinforced. The reinforcement with a lower weft is used primarily for woollen yarn pieces because the increase of weaving labour costs does not play such an important role here. Also in worsted cloth if, for example, a greater increase in weight is to be achieved without major impact on appearance and price by using woollen yarn.

Double fabric
Double fabrics are two fabrics lying on top of each other that are more or less firmly connected. Double fabrics are used:

• to reinforce the fabric and simultaneously increase its weight

• to influence weaving and material costs by using other materials in the lower fabric

• to create different face and reverse sides in terms of colour and pattern

In the ladies' outerwear and men's outerwear sectors double fabrics are used for both worsted yarn pieces and woollen yarn pieces. For this purpose, both technical aspects (weight, combination of worsted/woollen yarn) as well as fashion requirements (different colours/patterns) are reasons for using a double fabric weave.