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

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

3. 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.

4. 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

5. 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.

6. Weave Float

7. 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.

8. 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.

9. 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?

10. What weave makes the strongest fabric?

11. 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.

12. 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.

13. 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

14. 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.

15. 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.