Yarn
| Infobox on Yarn | |
|---|---|
| Example of Yarn |  |
| Facts | |
| Origin | - |
| Stowage factor (in m3/t) |
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| Humidity / moisture |
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| Ventilation | 6 air changes/hour (airing) if the dew point of the external air is lower than the dew point of the hold air |
| Risk factors | Self heating, odor, contamination, mechanical influences, insect infestation |
Yarn
Description
Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery and ropemaking. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for hand or machine embroidery.
Natural fibers
The most common plant fiber is cotton, which is typically spun into fine yarn for mechanical weaving or knitting into cloth. The most commonly used animal fiber is wool harvested from sheep. For hand knitting and hobby knitting, thick wool yarns are frequently used.
Other animal fibers used include alpaca, angora, mohair, llama, cashmere, and silk. More rarely, yarn may be spun from camel, yak, possum, qiviut, cat, dog, wolf, rabbit, or buffalo hair, and even turkey or ostrich feathers. Natural fibers such as these have the advantage of being slightly elastic and very breathable, while trapping a great deal of air, making for a fairly warm fabric.
Other natural fibers that can be used for yarn include linen and cotton. These tend to be much less elastic, and retain less warmth than the animal-hair yarns, though they can be stronger in some cases. The finished product will also look rather different from the woollen yarns. Other plant fibers which can be spun include bamboo, hemp, corn, and soy fiber.
Synthetic fibers
A number of synthetic materials are also commonly made into yarn, chiefly acrylic. All-acrylic yarns are available, as are wool-acrylic blends in various proportions. Some other synthetics are available as well; yarn designed for use in socks frequently contains a small percentage of nylon, and numerous specialty yarns exist.
Comparison of material properties
In general, natural fibers tend to require more careful handling than synthetics because they can shrink, felt, stain, shed, fade, stretch, wrinkle, or be eaten by moths more readily, unless special treatments such as mercerization or superwashing are performed to strengthen, fix color, or otherwise enhance the fiber's own properties.
Protein yarns (hair, silk, feathers) may also be irritating to some people, causing contact dermatitis, hives, wheezing or other reactions. Plant fibers tend to be better tolerated by people with sensitivities to the protein yarns, and allergists may suggest using them or synthetics instead to prevent symptoms. Some people find that they can tolerate organically grown and processed versions of protein fibers, possibly because organic processing standards preclude the use of chemicals that may irritate the skin.
When natural fibers are burned, they tend to singe and have a smell of burnt hair; synthetic yarns tend to melt. Noting how an unidentified fiber strand burns and smells can assist in determining if it is natural or synthetic.
Synthetic yarns, because of their construction as long, extruded strands, do not pill the way natural yarns can.
Yarns combining synthetic and natural materials inherit the properties of each parent, according to the proportional composition. Synthetics are added to lower cost, increase durability, add unusual color or visual effects, provide machine washability and stain resistance, reduce heat retention or lighten garment weight.
Structure
Spun yarn is made by twisting or otherwise bonding staple fibres together to make a cohesive thread, or "single”. Spun yarns may contain a single type of fibre, or be a blend of various types. Combining synthetic fibres (which can have high strength, lustre, and fire retardant qualities) with natural fibres (which have good water absorbency and skin comforting qualities) is very common. The most widely used blends are cotton-polyester and wool-acrylic fibre blends. Blends of different natural fibres are common too, especially with more expensive fibres such as alpaca, angora and cashmere. Bamboo yarn is a less expensive type that is a recent innovation.
Yarns are selected for different textiles based on the characteristics of the yarn fibres, such as warmth (wool), light weight (cotton or bamboo), durability (nylon is added to sock yarn, for example), or softness (cashmere, alpaca). Acrylic yarn is the least expensive.
Yarns are made up of a number of singles, which are known as plies when grouped together. These singles of yarn are twisted together (plied) in the opposite direction to make a thicker yarn. Depending on the direction of this final twist, the yarn will be known as s-twist or z-twist. For a single, the direction of the final twist is the same as its original twist.
Filament yarn consists of filament fibres (very long continuous fibres) either twisted together or only grouped together. Thicker monofilaments are typically used for industrial purposes rather than fabric production or decoration. Silk is a natural filament, and synthetic filament yarns are used to produce silk-like effects.
Texturized yarns are made by a process of air texturizing (sometimes referred to as taslanizing), which combines multiple filament yarns into a yarn with some of the characteristics of spun yarns.
Applications
Yarns are further processed by doubling, weaving, machine knitting, for sewing or knitting purposes.
Shipment / storage
Packaging
Yarns are shipped in containers on spools or as skeins, principally in folding cartons but also in bales (sometimes strapped with metal strapping), bags and boxes. They must be so packaged as to ensure that the spools do not chafe against each other or against the packaging, as this would result in the loss of whole spools. Skeins must be so secured as to prevent them from coming undone.
Cargo handling
In damp weather (rain, snow), the cargo must be protected from moisture, since yarns are strongly hygroscopic and readily absorb moisture. No hooks of any kind should be used, since they may very easily cause damage.
Stowage space requirements
The product must be stowed away from heat sources in clean, dry holds (containers).
Risk factors
- Self-heating / Spontaneous combustion
- Moisture
- Odor
- Contamination
- Mechanical influences
- Insect infestation / Diseases