9/5/13

Woven Effects

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Hand embroidery has been used for many centuries to add decoration to fabrics. With the invention of the automatic loom came the production of looms that would create ornamental effects similar to that of embroidery. 

Clipped or Unclipped Spot Weave 
Embroidery like designs may be achieved through the use of extra warp and extra filling yarns. In the clipped spot weave, either an extra shuttle or an extra set of warp yarns interlace to create a simple woven design. The extra yarns are carried along as a float on the wrong side of the fabric when they do not appear in the design. After the cloth is completed, the long floats may be cut away (clipped) or left uncut (unclipped). 

If clipped, which is the most common practice, the yarns form a characteristic “eyelash” effect. Sometimes these fabrics are used inside out for design interest. 

The durability of the design depends on the closeness of the weave of the fabric into which it is woven. Some domestic dotted Swiss fabric is constructed by the clipped spot weave. This sheer cotton fabric uses small clipped spot yarns in contrasting color to create a dotted surface design. Dotted Swiss may also be made with flocking or with plastic dots, much cheaper options. 

Interwoven, or Double-Cloth, Fabrics 
Interwoven fabrics are also called double-cloth fabrics. They are made with three, four, or five sets of yarns.
Double-faced fabrics are made with three sets of yarns. Woven either from two sets of warp yarns and one filling yarn or from two sets of filling yarns and one warp yarn, the effect of the weave is to produce the same appearance on both sides of the fabric. Some blankets and double-faced satins are examples of fabrics that are woven in this way. Fabrics made with four sets of yarns use two sets of warp yarns and two sets offilling yarns. 

Yarns from both layers move back and forth from one layer to another, as required by the design. In some areas the two fabrics are totally separated; in others, all four sets of yarns are interwoven. The two layers of these fabrics cannot be separated without destroying the fabric. The cut edge of the fabric will show small “pockets” where fabric layers are separate. The pocket boundaries are the point at which yarn sets interchange from one side of the fabric to the other. 

Fabrics with five sets of yarns are produced in the same way as double-woven pile fabrics. Two separate fabric layers are constructed. Extra yarns travel back and forth between the two layers to hold them together. These fabrics are often reversible, with one side being of one color and one side of another color. If the connecting yarn is cut, the two segments of the fabric can be separated into two individual pieces of cloth 

Triaxally Woven Fabrics 
Research and development of new fabric construction is constantly in progress. There is, however, another method of constructing fabrics that is closely related to traditional weaving, and it is known as triaxial weaving. The term is derived from trimeaningm “three” and axial, meaning “of or pertaining to the axis or center line.” In other words, triaxial fabrics have three axes or center lines. Traditionally, woven fabrics have a biaxial form or two axes, the lengthwise and crosswise axes. 

Triaxial fabrics are usually woven by interlacing two sets of lengthwise yarns with one set of crosswise yarns. Special cams in the loom manipulate the yarns so that the double set of yarns is carried in a diagonal direction. All three sets of yarns interlace. Triaxial weaves are not entirely new. Snowshoes and some forms of basketwork sometimes have been made using a triaxial construction. The major advantage of triaxial weaving is in its stability against stretching not only in the length and crosswise directions but also in the bias. Even those biaxial fabrics with good stability in the warp and filling will stretch in the bias direction. Triaxially woven fabrics have high bursting strength resistance and strong resistance to tearing and raveling. Strength is uniform in all directions. 
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Twill fabric | Woven fabric with diagonal line

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Twill Weave: 
Twill weaves produce diagonal lines on the cloth. In twill weave, the filling yarn interlaces more than one warp yarn (but never more than four, as strength would be sacrificed by doing so). On each successive line, or pick, the filling yarn moves the design one step to the right or to the left, thus forming the diagonal. 

Twill fabrics are readily identified by the diagonal lines that the weave creates on the surface of the fabric. Because there are fewer interlacing, the yarns in twill fabrics can be spaced closely together, packed tightly, and held firmly in place. Therefore, twill fabrics are usually strong and durable; they are also supple and drape well. Most twillweave fabrics are made in bottom weight. The compact structure of twill fabrics enables them to shed soil readily, although when soiled they may be difficult to get clean. Depending on their construction, twill fabrics generally show good resistance to abrasion. Twill fabrics are often used for tailored garments, particularly those made of worsted wool yarns. 

The simplest twill weave is created by the warp yarn crossing over two filling yarns, then under one, over two, under one, and so on. In the next row, the sequence begins one yarn down. The area in which one yarn crosses over several yarns in the opposite direction is called a float. 

The lines created by this pattern are called Wales. When the cloth is held in the position in which it was woven, the Wales (diagonal lines) will be seen to run either from the lower left corner to the upper right corner or from the lower right to the upper left. If the diagonal runs from the lower left to the upper right, the twill is known as a right-hand twilL About 85 percent of all twill-woven fabrics are right-hand twills (American Fabrics 1980, 325). When the twill runs from the lower right to the upper left, the twill is known as a left-hand twilL (See 

There are a number of types of twill weaves. All use the same principle of crossing more than one yarn at a regular, even progression. Descriptions of twills may be made in terms of the pattern of warp yarns crossing filling yarns. The description of twill weaves is notated as 2/1, 2/2, 3/2, and so on. The first digit refers to the number of filling yarns crossed over by the warp and the second digit to the number of filling yarns the warp passes under before returning to cross the filling again. 

When the crossing is over and under the same number of yarns, the fabric is called an even or even-sided twill. When warps pass over a larger or smaller number of filling yarns than they pass under, the fabric is called an uneven twill 



Even Sided Twill weave
The even-sided twill has the same number of warp and filling yarns showing on the face of the fabric. Figure 15.7 shows how such a weave is achieved in a 2/2 twill. Even-sided twills are reversible unless printed or finished or one side. 

1. Serge is a popular basic twill fabric made from any number of differentfibers. When serge is made from wool, it is often woven from worsted yarns. Serge will take a crease well, but wool serge tends to become shiny with wear. It tailors well. 
2. Flannel, if made of wool, is usually a twill weave with a napped finish. 
3. Plaids or tartan patterns are yarn-dyed even-sided twills. 
4. In a herringbone twill the direction of the twill reverses itself to form a broken diagonal that appears like a series of V’s: herringbone patterns create a decorative effect. Herringbone twills are common in suiting fabrics. 



Filling Faced Twill weave
Filling-faced twills have a predominance of filling yarns on the surface of the fabric. Filling yarns are generally weaker than are warp yarns, so that relatively few filling faced twills are made. 



Twill Angles 
When the face of a twill fabric is examined, the diagonal of the Wales will be seen to move at a more or less steep angle. The steepness of the angle is dependent on two factors in the construction of the fabric: the number of warps yarns per inch of fabric and the number of steps between movement of yarns when they interlace. 

The more warp yarns in the construction, the steeper the angle of the Wales, provided that the number of filling yarns per inch remains the same. This is because the points of interlacing of the yarns will be closer together; thereby the diagonal of the 

Wales will make a steep climb upward. When the steepness of the angle is the result of close spacing of warp yarns, these steeper angles are an indication of good strength. If the angle the wale makes with the filling yarn is about 45 degrees, the fabric is a regular twill Fabrics with higher angles are steep twills, and those with smaller angles are reclining twills.Generally, the interlacing of yarns in twill changes with each filling yarn. There are, however, fabrics in which the interlacing of yarns changes only every two filling yarns or every three filling yarns. The less often the interlacing changes, the steeper the angle of the twill will be.In the left hand twill, the diagonals run upward to the left. In the right hand twill, the lines run upward to the right. 


Herringbone twill weave

A Herringbone weave has vertical stripes of both right and left hand twills. 
Characteristics of Herringbone twill : 
• Strong and Durable fabric. 
• Twill weaves have fewer interlacing than the plain weave, which permits more yarns per inch in the fabric and makes them more stronger, heavier and more durable than plain, rib and basket weave fabrics. The floats are short, so yarn snagging is not a problem. 
• Increased drapablility and resilience than the plain weave. 
• Interesting designs 
• Ex: Denim, tweed, Jean Right-hand twill weave
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