Wednesday, January 9, 2013

Novelty Fabrics from Basic Weaves

Novelty effects in fabrics are in large part a result of selection of novelty yarns for incorporation into fabrics made in one of the basic weaves. 

Crepe Fabrics 
Crepe weave fabrics is special novelty fabrics from basic weaves may be defined as fabrics characterized by a crinkled, pebbly surface. Originally, crepe fabrics were made from crepe yarns, that is, yarns with an exceptionally high degree of twist, up to sixty-five turns per inch. Most standard crepe fabrics were made in the plain weave, some with rib effects, and some in satin weave, as in crepe-backed satin. With the advent of synthetic fibers, however, many crepe effects are achieved through the use of textured yarns, bicomponent yarns in which uneven shrinkage creates a crepe like surface, or embossing or stamping a crepe like texture on the surface of the fabric. Most fabrics made from these more recent processes will be durable only if they are made from heat-treated thermoplastic fibers. Another method uses a special crepe weave that breaks up the surface of the cloth into a random sequence of interlacings. Careful examination of fabrics having a crepe like appearance will reveal that relatively few of them are actually woven with crepe yarns. 

Seersucker, another plain-weave fabric, is created by holding some warp yarns at tight tension, some at slack tension. Those at slack tension puff up to form a sort of “blister effect.” Seersucker surface effects are permanent. Often the slack and tight yarns are each made from a different colored yarn, to provide a decorative striped effect. Seersucker should not be confused with fabrics having puffed effects created by chemical finishes, such as plisse or embossing, which are much less durable. 

Hand-Woven Tapestries 
Tapestries woven by traditional methods differ from jacquardwoven fabrics having the appearance of a tapestry in that the traditionally woven tapestries are made using hand techniques. Jacquard-woven tapestry fabrics generally use repeated patterns of finite size. Traditional tapestry weaving is used to produce enormous fabrics that can form one large picture. Tapestry weaving may be compared to painting with yarn. Since it is basically a hand technique, tapestry is made on an elementary loom. 

In the weaving of European tapestries, the loom followed the basic form of the two-bar loom. The loom was set up either vertically or horizontally, and warp yarns were measured and affixed to the loom. Filling yarns were prepared in the appropriate colors. The design of the tapestry was first worked out in a drawing, or cartoon, as it was called. The artist who created the drawing may have been one of great stature, and painters such as Raphael and Rubens served as designers of sixteenth- and seventeenthcentury tapestries. The cartoon was sometimes traced onto the warp yarns. In other instances it was mounted behind the loom, and the tapestry weaver looked through the warp yarns to the design, following the plan of the drawing. The tapestry was woven with the wrong side facing the weaver. Sometimes a mirror was set up beneath the tapestry so that the weaver could check the progress on the right side. The various colors of yarns were wound onto sharp, pointed bobbins that were introduced into the warp, and the weaver proceeded to fill in the area of that particular color. When the weaver reached the end of one color, a new bobbin was used for the next section. This created a problem, because as the weaver worked back and forth in a particular segment of the 

design, the yarns of one color did not join with the yarns of the adjacent color. This produced slits in the fabric at the place where each new color began. Sections of the tapestry could be sewn shut, but this caused the fabric to be weaker at the spots where the fabric was seamed together. Two other methods were also used to prevent the formation of slits. Where the color of one section ended and another began, both the old and the new color could be twisted around the same warp yarns. This system worked well except that it created a slightlyindistinct or shadowy line. Where clear, well-defined lines were required, the yarns of adjacent colors were fastened together by looping one yarn around the other.In traditional tapestry weaving, all the warp yarns are completely covered by filling yarns, so it is the filling yarns that carry the design. The warp yarns serve only as the base.

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