Denim, unlike many types of cloth (which are woven in one place and sent to another for dying), is woven and dyed at one location.
Preparing the cotton yarn
•1 There are several steps between ginned cotton (cotton after it has been picked from fields and processed) and cotton yarn. The incoming cotton is removed from tightly packed bales and inspected before undergoing a process known as carding. In this process, the cotton is put through machines that contain brushes with bent wire teeth. These brushes—called cards —clean, disentangle, straighten, and gather together.
Unlike many other cloths, denim is dyed before it is woven. The dye used is generally a chemically synthesized indigo. The denim is dipped in the dye vat several times so that the dye forms many layers. This explains why blue jeans fade after washing.
The yarn is then woven on large shutle-less looms. The blue threads are woven with white threads, but because the blue threads are packed closer together than the white ones, the blue color dominates the cloth.
cotton fibers. At this point, the fibers are called slivers.
•2 Other machines join several slivers together, and these slivers are then pulled and twisted, which serves to make the threads stronger. Next, these ropes are put on spinning machines that further twist and stretch the fibers to form yarn.
Dyeing the yarn
•3 Some cloths are woven (see step 5 below) and then dyed, but denim is usually dyed with chemically synthesized indigo before being woven. Large balls of yarn, called ball warps, are dipped in the indigo mixture several times so that the dye covers the yarn in layers. (These many layers of indigo dye explain why blue jeans fade slightly with each washing.) Although the exact chemicals used in such dyeing procedures remain trade secrets, it is known that a small amount of sulfur is often used to stabilize the top or bottom layers of indigo dye.
•4 The dyed yarn is then slashed; that is, it is coated with sizing (any one of a variety of starchy substances) to make the threads stronger and stiffer. Once this operation is complete, the yarn threads are ready to woven with undyed filling yarn threads.
Weaving the yarn
•5 The yarn is then woven on large mechanical looms. Denim is not 100 percent blue, as the blue dyed threads forming the warp (long, vertical threads) are combined with white threads forming the weft (shorter, horizontal
The denim cloth is cut into pattern pieces from stacks 100 layers thick. High-speed cutting machines are used for this process. Once the pieces are cut, they are sewn into completed pairs of blue jeans. Sewing is done in assembly-line fashion using human-operated sewing machines.
threads). Because denim is woven with the blue threads packed closer together than the white threads and with the blue threads covering three out of four white threads, the blue threads dominate. (By examining a piece of denim closely one can detect the steep diagonal pattern that results from this process, which is known as a three-by-one right-hand twill weave.) Although mechanized looms make use of the same basic weaving procedure as a simple hand loom, they are much larger and faster. A modern "shuttle-less" loom (which uses a very small carrier instead of the traditional shuttle to weave the weft threads between the warp threads) may produce as much as 3,279 yards (3,000 meters) of cloth 3.28 or 4.37 yards (three or four meters) wide in a single week. As much as 1,093 yards (1,000 meters) of cloth may be rolled into a single huge bolt.
•6 At this point the denim is ready for finishing, a term referring to a variety of treatments applied to cloth after it is woven. With denim, finishing is usually fairly simple. The cloth is brushed to remove loose threads and lint, and the denim is usually skewed in a way that will prevent it from twisting when it is made into clothing. The denim may then be sanforized, or preshrunk. Preshrunk denim should shrink no more than three percent after three washings.
Making the blue jeans
•7 Once the desired design is selected, patterns from the design are cut from heavy paper or cardboard. Up to 80 different sizes are possible from one pattern. The pieces of denim are then cut with high speed cutting machines from stacks 100 layers thick. Excluding rivets, buttons, and zippers, a pair of blue jeans contains about ten different pieces, from the pockets to the leg panels to the waistband and belt loops.
•8 The pieces of denim are ready to be sewn at this point. Sewing is done in an assembly line fashion, with rows of industrial human-operated sewing machines. Each sewer is assigned a specific function, such as making only back pockets. First, the various pockets and belt loops are assembled. Next, one sewer attaches the pockets to the leg seams, another then sews the leg seams together, and still another attaches the waist-band. Once the waist band is secure, the belt loops may be stitched on and the buttons attached. If the jeans include a zipper, it is then sewn into place, and the pants are hemmed. Finally, the rivets are placed in the appropriate places and the maker's label is sewn on last.
•9 Some jeans are prewashed and/or stone-washed to alter the appearance or texture of the finished jeans. Prewashing involves washing the jeans in industrial detergent for a short time to soften the denim. Stone-washing also means washing the jeans, but pumice is added to the load, resulting in a faded appearance. Small stones (less than one inch [one centimeter] in diameter) produce an even abrasion, while large stones (about four inches [10 centimeters] in diameter) highlight the seams and pockets and produce a more uneven appearance.
•10 The completed pair of blue jeans is I 0 then pressed. They are placed into a large pressing machine that steam irons the entire garment at once in about a minute. A size tag is punched into the material and the jeans are folded, stacked, and placed in boxes according to style, color, and size before being sent to the warehouse for storage. When the jeans are selected to be sent to a store, they are put in large shipping cartons and sent on freight trains or trucks.
Content Source: Madehow
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