How Is Cloth Made From Thread? Two Sets of Yarn Crossing

Cloth is made by interlacing warp threads, which run the length of the fabric, with weft threads passed across them, and the strength and appearance come from that interlacing. A loom performs four operations repeatedly. It holds the warp under even tension, which is essential since uneven tension produces distorted cloth. It separates the warp into two sets so a gap opens between them, which is called the shed and which is what allows the weft to pass in one motion rather than being threaded over and under each thread individually. It carries the weft across through that gap. And it beats the new weft thread firmly against the previous one to close the cloth. Everything else is a refinement of those four.

Each development addressed a specific limitation:

• •Warp-weighted looms, with threads hanging from a beam and tensioned by weights, used across Europe and the Mediterranean
• •Backstrap looms, tensioned between a fixed point and the weaver's body, portable and still in wide use
• •Horizontal frame looms with foot-operated heddles, which freed both hands and raised speed enormously
• •The flying shuttle from 1733, which let the weft be thrown across rather than passed by hand and widened the cloth
• •Drawlooms and then the punched-card mechanism of 1804, which controlled each warp thread individually and made complex patterns repeatable
• •Power looms from the same period, mechanising the whole cycle

What distinguishes plain cloth from patterned is which warp threads are raised for each pass, and the mechanism controlling that is the interesting part. In a simple loom, warp threads are threaded through heddles mounted on frames called shafts, and raising a shaft raises all the threads on it, so the number of shafts limits how complex a pattern can be, with four or eight covering a great many traditional weaves. For patterns needing individual control of every thread, a different mechanism is required, and the punched-card system developed by Joseph Marie Jacquard supplied it, with each card specifying which threads rise for one pass and a chain of cards encoding an entire design. That arrangement is the direct ancestor of programmable machinery and of stored-program computing.

A small number of interlacing patterns account for most cloth and each has characteristic properties. Plain weave alternates over and under on every thread and every pass, which is the simplest, the most stable and the least drapey, and it covers everything from muslin to canvas depending on the yarn. Twill passes the weft over two or more warp threads and shifts the pattern by one each row, which produces the diagonal line visible in denim and gives a cloth that drapes better and resists soiling. Satin floats threads over several others before binding, which puts a smooth reflective surface on one face at the cost of snagging easily. Combinations and variations of these three, together with yarn choice and finishing, produce essentially the whole range of woven fabric.

The requirements of the loom shaped the whole textile system around it. Warp threads are under tension and abraded constantly, so they must be stronger and more tightly spun than weft, which means spinning had to produce two different yarns and the preparation differed accordingly. Setting up a loom by threading hundreds or thousands of warp ends through heddles takes far longer than weaving the cloth, which is why weavers keep a warp on the loom and tie new warps onto the ends of old ones rather than rethreading. Mechanising weaving before spinning created a shortage of yarn, which drove the spinning inventions of the eighteenth century, and the resulting imbalance between the two operations is a standard illustration of how one bottleneck moves to the next.

A loom tensions the warp, separates it to open a gap, carries the weft through and beats it home, and every development refines those four operations. The number of shafts limits pattern complexity, and the punched-card mechanism of 1804 gave individual control of every thread. Setting up a warp takes far longer than weaving, which is why weavers tie new warps onto old ones.