Point Paper and Weave Float Dr. Jimmy Lam Institute of Textiles & Clothing

Learning Objectives n Weave layout and point paper n Effect of weave float n Which weaves make strongest fabric?

Weave layout (1) n Weave layout is to show the up and down movement of warp/weft yarns to make a woven fabric. n Graph paper (point paper) is used to show the order in which the yarns interlace in a fabric. (Plain or twill or satin weave) n It is used by textile designers to portray their designs. It is used by textile technicians to analysis fabric weave. n Each vertical row of squares represents a warp yarn and each horizontal row of squares represents a weft yarn. n A warp yarn crossing over a weft yarn is shown by marking in the square.

Example of ¼ satin weave on point paper Warp /weft yarn interalcing Point Paper notation Warp yarn upShown as black square Weft up Shown as White square

Weave layout (2) n A blank square is used to show the weft yarn passing over the warp. n The weave diagram, however, does not show the relative yarns per inch or are the yarn size and type used. n To illustrate the fabric weave on point paper, every interlacing in one repeat must be examined to determine the warp or weft is the surface yarn.

Weave Float

Weave float (1) n Warp yarns and weft yarns in a fabric interlace with each other. n When one yarn does not interlace with the next adjacent yarn, but passes over two or more adjacent yarns, it is said to be float. n If the yarn passes over two yarns and then interlaces with third yarn, it is said to be float of two. n A float of four, would refer to a yarn which passed over four yarns and then interlaced with the fifth yarn. n If a warp yarn passes over two or more adjacent weft yarns, a warp float results. When the weft yarn passes over the warp yarns, weft float occurs.

Weave float (2) n If the float is relatively long, a snagging problem results. n The yarn can easily catch and break on broken fingernail or rough surface. n Floats also weaken the fabric since they reduce the frequency with which yarns pass from one side of fabric to the other. n This can be offset by increasing the yarns per inch of the fabric. n Floats tend to make the fabric surface flat and increase the amount of lustre. n They also enable yarns to slide under each other in the fabric and are, therefore, used when fabrics of higher yarns per inch are to be made.

Discussion n How to represent the fabric design on point paper? n What are the limitations of point paper? n Explain how float weave will reduce the fabric strength? n Why a float weave would allow more ends/picks per inch on a fabric?

What weave makes the strongest fabric?

Weave and Fabric Strength (1) n Usually, the plain weave will provide the strongest fabric (highest breaking strength). n The reason is that more yarn interlacings provide for higher fabric strength (more frictional force between each yarn). n All other weaves (twill or satin) have floats which reduce the number of interalcings. n Apart from weave design, fabric density (ends or picks per inch) would affect fabric strength.

Weave and Fabric Stength (2) n If the number of yarns per inch of one fabric is higher than that of a comparable fabric, then the fabric with more yarns per inch in the indicated direction would be stronger. n The higher yarns per inch will more than offset the loss of strength from a weave having fewer interlacings. n Weave with floats can produce fabric with more yarns per inch.

Weave structure (plain or twill) affects The yarns per inch of a fabric Plain structure, only SIX ends per unit 2/2 twill, however, up to EIGHT ends per unit As more yarns per unit in twill structure, twill weave is stronger than plain weave

Weave and Fabric Stength (3) n Weaves with long floats can produce the strongest fabric because these fabrics can be made with the most yarns per inch. n With long floats, yarn can slide under one another, and bunch together. n This cannot occur with a plain weave, since with every other yarn interlacing, the yarns are positioned side by side. They cannot bunch together. n Thus, satin weave fabric can be made with most yarns per inch (longest float) and so can be made stronger than twill weaves (shorter float). n For the same reason twill weave fabrics can be made stronger than plain weave fabrics.

Discussion n What is the relationship of fabric density (ends/picks per inch) to fabric strength? n Why a long float design would make a higher fabric density? n Explain why fabric strength of satin is stronger than twill and why plain is the weakest amongst all of them, assuming they use the same yarn count and yarn type.