Selvage and Raw Edges

239.367A Figure 10-1.—Textile terms. Selvage and Raw Edges The selvage edges of material, as shown in figure 10-1, are the edges of cloth, tape, or webbing that are woven to prevent raveling. When the material is cut, the resulting edge at the cut is referred to as a raw edge. Warp There are threads that run lengthwise of the cloth parallel to the selvage edge. If there is a difference in the strength of the warp and filling threads, the warp threads are usually stronger, because they form the framework for the material and support most of the strain during the weaving process. Figure 10-1 shows both warp and filling threads. Filling Filling is also referred to as a woof, weft, or pick. It is the threads that run crosswise to the cloth as it comes from the loom. This term is not to be confused with filling in the sense of sizing, which means the addition of substances that give body or decrease porosity of the material. Warp and filling threads must be determined in pattern layout because patterns (unless otherwise stated) are always cut with the warp and filling. Weave The weave is an interlacing of two sets of threads (warp and filling) to form a specific pattern. The manner in which the material is woven or constructed affects many of the cloth properties, such as tensile strength, air permeability, and elongation. Bias A bias is a diagonal line of a cut, a fold, or a seam across a piece of textile material at an angle of 45 degrees to the direction of the filling threads in the material. Bias construction is used to save material, prevent tearing between sections, and provide elasticity where it is a requirement for a satisfactory performance of the article. The bias direction of the fabric has a greater stretching quality than the straight direction. A bias cut is shown in figure 10-1. Tensile Strength The force required to break a material is called tensile strength. The tensile strength of a fabric is stated in pound-per-inch width for warp and filling. The tensile strength of webbings and tapes is stated for the full width. Cloth Weight The cloth weight is the weight of a cloth, or fabric, in ounces per square yard. All fabrics have a designated cloth weight. For instance, a square yard of cotton duck may weigh 8 ounces; therefore, it is called 8-ounce duck. CONSTRUCTION FEATURES AND USES OF VARIOUS TEXTILE MATERIALS If a cigar ash burns a hole in your tweed jacket, you will not patch it with a piece of velvet material. If a life raft needs repair, you will not use tweed fabric to repair it. Or, if an NES 12 canopy needs repair, you won’t use 7.25-ounce nylon duck. If a repair is to make an item usable, must use like material. In the not too distant past we were limited to natural fibers as a source for our fabrics and associated materials; but today, with the advent of synthetic fibers, we can enjoy their improvements in some respects over the natural fiber. Currently the natural and synthetic fibers have their respective advantages and disadvantages. Because you cannot use synthetic or natural fiber materials exclusively, you must decide which one best serves your purpose. There 10-2