Fabric is made up of three elements—the warp, the weft, and the space between them. The warp is a series of parallel threads running lengthwise; the weft is a series of parallel threads running width- wise. When interlaced as fabric, the warp and weft threads meet at right angles. The interval between them is the interspace.
Fabric can and does express ideas on many levels: aesthetic, tactile, and utilitarian. Making fabric is a creative process, which begins with designing the warp. This is where the thinking and visualizing of the end product take place. The choices made in designing the warp are controlled both by the designer and by the inherent characteristics of the medium—yarn. Designing the warp involves selecting and positioning the warp threads, evaluating how they will interact with the weft threads to create the interspace, and finally calculating the total amount of yarn that will be needed for the finished fabric.
Identifying fibers—Fiber is the raw material that, when constructed or spun, produces yarn. A knowledge of fibers and yarns is essential to fabric construction. Knowing their behavior on and off the loom enables you to make judgments about the fabric they will become. The more you know about your materials, the more control you have over them, and the better you can direct your results.
The burn test. The best way to identify a fiber is to burn it and then analyze how it burns and the odor it produces. Double the yarn a few times, and twist it at its center so that you have several loops at one end. Hold the yarn over a flame, and light the looped end. Watch how the fibers burn; then blow out the flame. Notice whether the fibers continue to burn or not, and what the ash looks like.
Wool, silk, rubber, and several synthetics produce a bead on the end of the burned material. To determine what kind of fiber
you have, you need to crush the bead—the bead of a synthetic will be difficult to crush. If you suspect the fiber is synthetic, wait until the bead cools before crushing it. A melted synthetic fiber is a liquid plastic that will stick to your fingers and burn you. If you’re not sure what fibers you are working with, consult Chart B on p. 68 after you’ve done the burn test. This chart is not comprehensive, but it lists some of the most common fibers.
The burn test is the most accurate method for identifying fibers, but it can be confusing. A finish on the fibers will leave a black ash that can distort your visual reading, although the odor of the burnt fibers will be unchanged. When burning a yarn that contains two or more fibers, especially natural blends, you will have difficulty distinguishing between them. In these cases, the feel of the fibers and their ability to take dyes will help you identify un-known fibers (see Chart C, p. 69).
Feel and dye receptability. Natural fibers feel like their raw or original states. Cotton yarns have the texture of raw cotton, and wool feels like sheep. Linen, which is from the stalk of a plant, feels stalky even when spun. The way fibers take dye has to do with their ability to chemically bond with the dye, but it also partly depends on the color in their original state. For example, raw cotton is almost white, so it takes dyes in clear colors. Raw linen is gray, so dyed linen is a hue of the color, unless it has been bleached first.
Selecting yarns—Yarns come in a variety of textures, diameters, and colors. The combinations allow for endless design possibilities. The need to constantly make decisions about the materials, to add and eliminate possibilities sparks a designer’s creativity. When selecting yarns, choose those that catch your eye, that inspire you. You’ll work better with materials you like. Spin and ply. Yarns can be made up of one fiber or combinations of fibers. The way the fibers are spun and/or plied deter-mines the texture and diameter of the yarn. Yarn fibers are spun in either of two directions: clockwise, to produce an S-twist, or counterclockwise, to produce a Z-twist (see drawings, p. 57). The twist of the fibers determines how the yarn reflects light. When yarns with different twists are used together, the subtle difference in the way they reflect light becomes obvious. Two yarns of the same color, but with different twists, can look like different shades.
Some yarns are simply twisted. These are called single-ply yarns, or singles. Others are plied, meaning they are made up of more than one twisted fiber. There are also a number of highly textured novelty yarns, such as slub, boucle, chenille, and ratine. Novelty yarns are plied yarns consisting of a core yarn, an effect yarn, and a binder yarn. Color. The larger a designer’s palette, the better. When choosing colors for warp threads, place all the yarns on a clean, neutral-colored table and stand back. Look for the colors that push forward, in other words, those that stand out. Most likely these colors will do the same thing when woven. A rule of thumb is this: Warm colors come forward, cool colors recede. Textured yarns jump visually because they are more active visually. In vivid colors they are even more active. Thick yarns will always overpower thin yarns.
Knowing how color suggests depth on a two-dimensional surface is invaluable for creating fabrics with dimension and richness. Color in weaving is like pointillist theory in painting. When two colors that are next to each other are viewed from a distance, they often blend to become a third color. To evaluate the overall effect of the yarns you plan to use for the warp, wrap them around either a white or neutral-colored piece of cardboard. Pack the threads tightly so the color of the cardboard doesn’t throw off the effect. You can also evaluate the effect of colored yarns by loosely twisting them together. To get an idea of how they will work with the weft threads, visualize them being interlaced. Shrinkage. Besides texture and color decisions, there are some functional considerations. Yarn shrinkage is important in calculating the length and width of a woven piece. For example, if you put on a warp and the yarns have a high shrinkage rate, the finished measurement of the washed and dried fabric will be less than that of the fabric you produced on the loom. By washing and drying a sample length of yarn, you can get some idea of how much it will shrink. Also, a yarn’s character frequen tly changes after the yarn has been washed and dried, and most times for the better. Some weaving yarns are shopworn or dirty when purchased, and some have been treated with a finish in the spinning process. Washing removes the dirt and the finish, allowing the fibers to “full” or “blossom." If the dye bleeds, you can plan ahead to send the finished piece to the dry cleaners.
Stretch. All yarns stretch at different rates because of the way the yarn was spun or the nature of the fiber it is composed of. Linen keeps its shape no matter how it is spun. Wool, on the other hand, always has some give, especially if the yarn was spun for knitting. Yarns that shrink at different rates can produce some interesting fabrics, but keep in mind the fabric’s purpose. For example, fabrics for window treatments need a certain amount of rcsilience so they don’t lose their shape with time and use. Strength. To work as a warp thread, a yarn must be strong. Warp threads take much more abrasion during the weaving than the weft threads ever will. They are stressed by being threaded through the hcddles and reed and by being in tension while moving through the beater.
There is one test that tells whether a yarn can be used as a warp thread. Hold the yarn taut and graze its surface with your thumbnails. This simulates the loom’s tension and abrasion. If you can perform this test ten times without breaking the yarn, you can be assured that the yarn will not break while you are weaving. If the yarn breaks after five times, you are taking a chance with it. For the sake of your design, however, it may be a chance worth taking.
Be sure to test the slub, or less twisted sections, of novelty yarns as well as the more twisted sections; the slub section is usually where breakage occurs. Also test the thin, overspun areas of singles yarns. If a yarn breaks in handling, it probably has been eaten by moths or has reached its shelf life. Throw it away. A cotton that you've had for thirty years, for example, is liable to break apart like paper.
Positioning yarns in the warp—There are no real limitations to the types of yarns you can use as warp threads. The charac-
tcristics of the materials should simply guide their placement in the warp. Using yarns with different degrees of strength, stretch, and shrinkage can create problems, but if you know the yarns' tendencies, you can avoid potential problems by how you position the yarns in the warp.
If you are using two yarns that have dif-ferent degrees of stretch, the warp will be stable if the stretchier yarn makes up less than half the warp threads and alternates with more stable yarns. If stripes of the stretching yarns, placed throughout the warp, are surrounded by more stable yarns, the warp will also be stable. The problem arises when the stretching threads make up a large stripe in the warp.
Their tendency to stretch gets worse as you weave, and the only solution is to weave with two beams to compensate for, and maintain, different tensions.
Likewise, if a wcak yarn makcs up less than half the warp threads and it alternates with strongcr yarns throughout the warp, the chancc that the weak threads will break is reduced considerably. If the yarns make up stripes throughout the warp, or one large stripe in the warp, they’ll tend to break. Weak threads on cither selvedge arc certain to break throughout the weaving process. Strength problems, like stretch problems, only get worse as you weave, and constantly having to mend broken warp threads can be madening When deciding whether to risk weak threads in a warp, consider the length of the warp. Broken threads in a short warp will try your patiencc much less than breakage in a long warp.
One way that you can strengthen a yarn is to wind it into two or more balls and then wind the strands all together as one. By doing this, you will makc a strong yarn consisting of multiple strands that are not plied. You can also do this with two or more different types of yarns in order to produce texturcs and colors that you would not be able to purchase.
Take care if you’re going to use highly textured yarns, such as boucle and mohair, as warp threads. These yarns tend to stick to themselves and to other yarns.
Weave structure—The way in which the warp and weft threads are interlaced is the weave structure. The weave structure integrates the yarns’ colors, textures, and dimensions to establish the rhythm of the fabric, and its interspace determines the fabric’s rigidity or pliability.
In a warp-faced weave, the warp threads are most visible in the woven fabric. In a balanced weave, equal amounts of the waqp and weft threads are visible, providing the yarns are of the same diameter. In a weft-faced weave, the weft threads predominate. Each weave structure creates a characteristic interspace. In a warp-faced weave, the interspace is long and narrow. In a balanced weave, the interspace is a square, and in a weft-faced weave, the interspace is short and wide. The density and rigidity of a plane of fabric are determined by the amount of interspace, by how far apart or close together the warp and weft threads are. The greater the amount of interspace, the more pliable the plane of fabric; the less interspace, the more rigid the plane of fabric. The amount of interspace is relative to the diameter of the yarn, so weave structurc works together with the yarn’s sett to create the density of a fabric’s weave.
Yarn sett. Sett is the number of warp threads that are required to fill 1 in. of fabric, referred to as ends per inch (epi). In order to calculate thc sett of the yarn for a particular project, you need to know the type of weave structure you will be using, but first determine what the yarn’s sctt is in a balanced weave. From the yarn’s sctt in a balanced weave, you can easily adjust the sett to create a warp-faced or a weftfaced weave.
First wrap the yarn around a ruler to the V2-in. mark. Be sure to pack it tightly, without overlapping the strands. Thcn count the number of threads it takes to till 12 in., and do the same for cach type of yarn in the warp. By wrapping your yarn to the 12-in. mark, you are measuring how many warp threads there will be in 1 in. of fabric in a balanced weave. The unwrapped 112 in. is the interspace, through which the
weft threads will travel as they go under and over the warp.
For example, if the yarn wraps around the ruler to measure 15 ends to the 12 in., 15 interspaces will be required to complete 1 in. in a balanccd-weave fabric. In a balanced weave, the weft will also measure 15 yarns and 15 spaces, measured in picks per inch (ppi), to create 1 sq. in. of fabric.
To create a warp-faced fabric with this same yarn, double the number 15 to make the sett 30 epi. By doing this, you arc removing the interspace and pu tting yarn in its place. Thirty is then the minimum number of threads needed to create 1 in. of this warp-faced fabric. If there are fewer than 30 threads in 1 in., more of the weft will show, and the plane of fabric will be more pliable. If there are more than 30 threads in 1 in., the interspace will be smaller, and the plane of fabric more rigid.
For a weft-faced fabric of the same yarn, you’d decrease the number of threads the balanced weave required. By taking away threads, you increase the interspace. There’s more room for the weft to be visible before it must go under a warp thread. The weft threads noat over the warp threads, so the plane, of fabric is more pliable.
Fabric, density To learn about fabric density, look at manufactured yardage. Analyze the size and sett of the yarns and the weave structure in relation to the weight and purpose of the fabric. There is nothing worse than a rigid apparel fabric that does not have any drape to it. A gravity-defying garment will look like a board enveloping the figure. On the other hand, a tapestry needs to be dense and somewhat rigid to hang properly and have the necessary visual impact.
The reed of the loom is where the density of the fabric is actually set up. Once it is set up, the warp’s density is constant, though the weft’s density depends on how firmly you pack the weft into the warp.
Calculating yardage-The next step in planning your warp is to calculate the yardage you’ll need. First multiply the number of ends per inch by the total number of inches needed for the width of your fabric (epi x total width = total number of ends for fabric width). Then determine how many inches of fabric you'll need for the length. For example, if you’re making a garment, you must know how many inches in length you’ll need for the whole piece, including fringe, hems, and seams. Write the measurements down on the same paper with the width calculations.
Don't forget to allow extra for shrinkage. An average shrinkage allowance is 20%. Multiply the number of inches in length needed for the fabric by the percentage of shrinkage. Add to this number the amount of loom waste, which is the length of yarn needed to tie on with, and the amount that extends from the apron rod up to the back of the harnesses. On most looms, this is between lk yd. and 1 yd.
Now add everything up: Total length in inches + (total length x shrinkage percentage) + loom waste = yardage needed. To simplify things, round off your total to the next V2 yd. Then multiply the total number of ends for fabric width by yardage needed. This is how much yarn you will need for the warp. (You will need the same amount of yarn for the weft in a balanced weave.) Finally, if you are using different types of yarns, divide the total amounts by the appropriate percentages of each material.
When you are buying yarns and don’t know their total yardage, weigh an article similar to the one you want to make, and simply buy approximately the same poundage of yarn. Calculate the proportions of warp and weft threads in the weave structure that you are using.
You are now ready to wind the warp.
