threadhacked

Old Machines, New Tech, No Kitsch.

Textile Theory

It’s cloth. How difficult can it be?

Well… it’s the oldest human technology, right after fire. There’s good evidence that people were making either cloth or felt or weaving reeds before wheels. We were definitely making leather and fur. 

Cloth divides along three lines: There’s woven fabric, felted fabric and knitted fabric. Woven fabric consists of many vertical threads (warp) crossed at near right angles with many horizontal threads (weft). The vertical threads are held under tension — weights, rollers or the body-weight of the weaver — while the hortizontal threads are woven in between. The simplest loom is a frame or board; the warp is wound from top to bottom and back  and the weft is manipulated with a needle or bodkin. Heddle looms alternate the threads as a group and looms get more complicated from there. Any fiber can be woven. 

Felted fabrics are almost always wool or other animal hair. They rely on the same matting principles that create tangles and dreds in hair — the scales on the individual fibers can be encouraged to lock together with enough warmth, pressure, friction or some combination. Non-woven fabrics like polypropylene (interfacing, landscape fabric) are effectively a form of felting, though not produced exactly the same way. 

Knitted fabrics consist of interlocking loops of yarn, made from a single string.  Almost any fiber can be knitted. 

The second division of fabrics are fiber content. The oldest fiber was probably reed or grass fibers, for basketry, because reeds and grass don’t run away. Second was probably felted hair or shed wool and leather. Our ancestors probably learned to rot grasses, mostly flax, to make them more pliable and break apart their fibers to spin, around the same time we started domesticating sheep and goats. Here, the major divisions are between plant fibers, animal fibers and the more recent synthetics. 

The primary plant fibers are cotton and linen, with ramie and hemp as secondary important plant fibers. Cotton is a warm weather crop that produces masses of fluff around the seeds to aid dispersal. It was both an Old World and New World plant, and was independently domesticated in both regions. Linen comes from the Eurasian flax plants, which is a cooler climate grass. After harvesting, linen is fermented in standing water to separate the 1-2 meter long fibers for spinning. Ramie is a relative of nettle plants and both looks and is treated much like linen. Hemp fiber was the primary rope fiber for most of history, but has been used for fabrics. Plant fibers are dyed with fiber-reactive dyes. (Rayon, which is a transitional synthetic, is made from wood chips or bamboo, and is treated like a plant fiber in terms of dying.) Linen has the lowest carbon footprint of the plant fibers, since more of the plant is used and very little of the production needs significant heat. Ramie and hemp are second, but the drought resistant properties of hemp have been overblown. To get good hemp fiber that can be finely spun and woven, the plant needs as much water as cotton. Cotton has the highest carbon footprint of the plant fibers. The plants are annuals, so they don’t keep producing once they’ve bloomed. They’re very thirsty, and mechanical harvesting and processing is necessary. Rayon can be a good carbon choice, if it’s made from the waste of tree farm trees, but if it’s from old-growth forest, it can be worse than animal fibers. Organic cotton is difficult to judge — organic farming produces less fiber, uses as much oil to run the machines, and uses more water, but the runoff usually has less potential contamination. Flax and ramie require far less fertilizer than cotton or textile hemp. 

Animal fibers are wool (sheep), cashmere (goats), angora (rabbit hair), mohair (other goats), llama, and silk. All animal fibers require an acid to dye, which means they can be dyed with Koolaid or food coloring plus vinegar or citric acid. With the exception of silk, animals are not killed to produce animal fiber. This does not mean they’re not harmed — shaving their hair can nick their skin and it can be frightening for young animals — but all of the species humans domesticated for fiber now depend upon us to shave them regularly. Animal fibers have the highest carbon footprint, but they also tend to last longer and degrade more slowly. Wool is a great thermoregulating fiber, both for warm weather — wool voile is as light as cotton voile — and cold, but it is more prone to felting, shrinkage and can be chewed up by wool moths. 

The exception to the no-kill basis is silk, which is produced from the chrysalis of the mulberry silkworm. There are two types of silk, one of which is effectively cruelty free, called Bombyx silk, wild silk or tussah silk. These are the discarded chrysalises of silkworms who have fully transitioned into moths and will reproduce. The fibers in the case are usually shorter, because the moth chewed through them to get out, and have a mineral coating that the caterpillar excretes to protect the delicate insect inside. Wild silk also dyes poorly, due to the mineralization.

Cultivated silkworms, like sheep and goats, also depend on humans for access to their preferred food, mulberry leaves. It takes 104 kg of mulberry leaves to make one kilo of silk fiber, regardless of whether that’s wild or cultivated silk. To cultivate the domesticated silk worm after it has spun its cocoon, the insect has to be killed, either with boiling water or a needle through the case. Silk’s carbon-footprint is somewhat mitigated by the mulberry trees planted to feed the worms, but not entirely. Silk is extremely strong and not nearly as delicate as its reputation indicates, but after about 100 years, it starts to shatter, meaning the proteins have so broken that they cannot support their length anymore. 

There are two transitional synthetics: rayon (also called viscose) and cellulose acetate, both made from some form of cellulose. Most clothing labeled as bamboo is a bamboo rayon. It’s a complex industrial process, and in the early days, it was exceptionally poisonous to the workers. (We’ve improved significantly.) Most rayon is more delicate when wet, with the exception of Tencel rayon. Both rayon and acetate usually breathe and wear like a plant-fiber fabric rather than a full synthetic. Acetate can be dyed with both acids and fiber-reactive dyes, though the colors can be inconsistent compared to their full plant or protein counterparts. Acetate is extremely delicate when wet. 

The last group are the full synthetics, which are spun fibers of coal, oil or liquid petroleum gas. A few bio-plastics are currently under investigation as alternate feedstocks for synthetic textiles fabrics, but we’re really not there yet. Plastics can also be recycled into spun fibers; disposable clear water bottles are often recycled into fleece. Most synthetics don’t breathe well, and so are often mixed with cotton or rayon to improve their wearability. Adding synthetics to cotton or linen also reduces wrinkling.  The exception is ITY knit, which tends to be fairly comfortable to wear. Unlike every other fiber so far, synthetics do not biodegrade and cannot be composted. 

This is the overview and specific qualities of fabrics and fibers will be discussed in other pages. 

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