Weaving


Weaving is a method of textile production in which two distinct sets of yarns or threads are interlaced at right angles to form a fabric or cloth. The longitudinal threads are called the warp and the lateral threads are the weft, woof, or filling. The method in which these threads are interwoven affects the characteristics of the cloth.
Cloth is usually woven on a loom, a device that holds warp threads in place while filling threads are woven through them. A fabric band that meets this definition of cloth can also be made using other methods, including tablet weaving, back strap loom, or other techniques that can be done without looms.
The way the warp and filling threads interlace with each other is called the weave. The majority of woven products are created with one of three basic weaves: plain weave, satin weave, or twill weave. Woven cloth can be plain or classic, or can be woven in decorative or artistic design.

Process and terminology

In general, weaving involves using a loom to interlace two sets of threads at right angles to each other: the warp which runs longitudinally and the weft that crosses it. One warp thread is called an end and one weft thread is called a pick. The warp threads are held taut and in parallel to each other, typically in a loom. There are many types of looms.
Weaving can be summarized as a repetition of these three actions, also called the primary motions of the loom.
  • Shedding: where the warp threads are separated by raising or lowering heald frames to form a clear space, referred to as the shed where the pick can pass
  • Picking: where the weft or pick is propelled across the loom by hand, an air-jet, a rapier or a shuttle
  • Beating-up or battening: where the weft is pushed up against the fell of the cloth by the reed
The warp is divided into two overlapping groups, or lines that run in two planes, one above another, so the shuttle can be passed between them in a straight motion. Then, the upper group is lowered by the loom mechanism, and the lower group is raised, allowing the shuttle to pass in the opposite direction, also in a straight motion. Repeating these actions forms a fabric mesh but without beating-up, the final distance between the adjacent wefts would be irregular and far too large.
The secondary motions of the loom are the:
  • Let off motion: where the warp is let off the warp beam at a regulated speed to make the filling even and of the required design
  • Take up motion: takes up the woven fabric in a regulated manner so that the density of filling is maintained
The tertiary motions of the loom are the stop motions: to stop the loom in the event of a thread break. The two main stop motions are the
The principal parts of a loom are the frame, the warp-beam or weavers beam, the cloth-roll, the heddles, and their mounting, the reed. The warp-beam is a wooden or metal cylinder on the back of the loom on which the warp is delivered. The threads of the warp extend in parallel order from the warp-beam to the front of the loom where they are attached to the cloth-roll. Each thread or group of threads of the warp passes through an opening in a heddle. The warp threads are separated by the heddles into two or more groups, each controlled and automatically drawn up and down by the motion of the heddles. In the case of small patterns the movement of the heddles is controlled by "cams" which move up the heddles by means of a frame called a harness; in larger patterns the heddles are controlled by a dobby mechanism, where the healds are raised according to pegs inserted into a revolving drum. Where a complex design is required, the healds are raised by harness cords attached to a Jacquard machine. Every time the harness moves up or down, an opening is made between the threads of warp, through which the pick is inserted. Traditionally the weft thread is inserted by a shuttle.
On a conventional loom, continuous weft thread is carried on a bobbin or pirn, in a shuttle that passes through the shed. A handloom weaver could propel the shuttle by throwing it from side to side with the aid of a picking stick. The "picking" on a power loom is done by rapidly hitting the shuttle from each side using an overpick or underpick mechanism controlled by cams 80–250 times a minute. When a pirn is depleted, it is ejected from the shuttle and replaced with the next pirn held in a battery attached to the loom. Multiple shuttle boxes allow more than one shuttle to be used. Each can carry a different colour which allows banding across the loom.
The rapier-type weaving machines do not have shuttles, they propel cut lengths of weft by means of small grippers or rapiers that pick up the filling thread and carry it halfway across the loom where another rapier picks it up and pulls it the rest of the way. Some carry the filling yarns across the loom at rates in excess of 2,000 metres per minute. Manufacturers such as Picanol have reduced the mechanical adjustments to a minimum, and control all the functions through a computer with a graphical user interface. Other types use compressed air to insert the pick. They are all fast, versatile and quiet.
The warp is sized in a starch mixture for smoother running. The loom warped by passing the sized warp threads through two or more heddles attached to harnesses. The power weavers loom is warped by separate workers. Most looms used for industrial purposes have a machine that ties new warps threads to the waste of previously used warps threads, while still on the loom, then an operator rolls the old and new threads back on the warp beam. The harnesses are controlled by cams, dobbies or a Jacquard head.
The raising and lowering sequence of warp threads in various sequences gives rise to many possible weave structures:
  • Plain weave: plain, and hopsacks, poplin, taffeta, poult-de-soie, pibiones and grosgrain
  • Twill weave: these are described by weft float followed by warp float, arranged to give diagonal pattern; examples are 2/1 twill, 3/3 twill, or 1/2 twill. These are softer fabrics than plain weaves.
  • Satin weave: satins and sateens
  • Complex computer-generated interlacings, such as Jacquard fabric
  • Pile fabrics: fabrics with a surface of cut threads, such as velvets and velveteens
  • Selvage refers to the fabric's edge, which may be marked with the manufacturer's detail. It is a narrow edge of a woven fabric parallel to its length.
  • Thrums are the remainder yarns for tying on the loom. The portion that is not weavable warp. It is also called loom waste.
Both warp and weft can be visible in the final product. By spacing the warp more closely, it can completely cover the weft that binds it, giving a warp faced textile such as rep weave. Conversely, if the warp is spread out, the weft can slide down and completely cover the warp, giving a weft faced textile, such as a tapestry or a Kilim rug. There are a variety of loom styles for hand weaving and tapestry.

Archaeology

There are some indications that weaving was already known in the Paleolithic Era, as early as 27,000 years ago. An indistinct textile impression has been found at the Dolní Věstonice site. According to the find, the weavers of the Upper Palaeolithic were manufacturing a variety of cordage types, produced plaited basketry and sophisticated twined and plain woven cloth. The artifacts include imprints in clay and burned remnants of cloth.
The oldest known textiles found in the Americas are remnants of six finely woven textiles and cordage found in Guitarrero Cave, Peru. The weavings, made from plant fibres, are dated between 10,100 and 9080 BCE.
In 2013 a piece of cloth woven from hemp was found in burial F. 7121 at the Çatalhöyük site, suggested to be from around 7000 BCE Further finds come from the Neolithic civilisation preserved in the pile dwellings in Switzerland.
Another extant fragment from the Neolithic was found in Fayum, at a site dated to about 5000 BCE. This fragment is woven at about 12 threads by 9 threads per centimetre in a plain weave. Flax was the predominant fibre in Egypt at this time and had continued popularity in the Nile Valley, though wool became the primary fibre used in other cultures around 2000 BCE.
The oldest-known weavings in North America come from the Windover Archaeological Site in Florida. Dating from 4900 to 6500 BCE and made from plant fibres, the Windover hunter-gatherers produced "finely crafted" twined and plain weave textiles. Eighty-seven pieces of fabric were found associated with 37 burials. Researchers have identified seven different weaves in the fabric. One kind of fabric had 26 strands per inch. There were also weaves using two-strand and three-strand wefts. A round bag made from twine was found, as well as matting. The yarn was probably made from palm leaves. Cabbage palm, saw palmetto and scrub palmetto are all common in the area, and would have been so 8,000 years ago.
Evidence of weaving as a commercial household industry in the historical region of Macedonia has been found at the Olynthus site. When the city was destroyed by Philip II in 348 BCE, artifacts were preserved in the houses. Loomweights were found in many houses, enough to produce cloth to meet the needs of the household, but some of the houses contained more loomweights, enough for commercial production, and one of the houses was adjacent to the agora and contained three shops where many coins were found. It is probable that such homes were engaged in commercial textile manufacture.

History

Weaving was known in all the great civilisations, but no clear line of causality has been established. Early looms required two people to create the shed and one person to pass through the filling. Early looms wove a fixed length of cloth, but later ones allowed warp to be wound out as the fell progressed. Weaving became simpler when the warp was sized.