Leather

From Wikipedia, the free encyclopedia

 

A variety of leather products and leather-working tools

 

Leather is a durable and flexible material created by tanning animal rawhide and skins. The most common raw material is cattle hide. It can be produced at manufacturing scales ranging from artisan to modern industrial scale. 

Leather is used to make a variety of articles, including footwear, automobile seats, clothing, bags, book bindings, fashion accessories, and furniture. It is produced in a wide variety of types and styles and decorated by a wide range of techniques. The earliest record of leather artifacts dates back to 2200 BC.

Production processes

Drying of leather in East Timor

 

Leather tanning in Fes, Morocco

 

Tanned leather in Marrakech

The leather manufacturing process is divided into three fundamental subprocesses: preparatory stages, tanning, and crusting. A further subprocess, finishing, can be added into the leather process sequence, but not all leathers receive finishing.

The preparatory stages are when the hide is prepared for tanning. Preparatory stages may include: soaking, hair removal, liming, deliming, bating, bleaching, and pickling. 

Tanning is a process that stabilizes the proteins, particularly collagen, of the raw hide to increase the thermal, chemical and microbiological stability of the hides and skins, making it suitable for a wide variety of end applications. The principal difference between raw and tanned hides is that raw hides dry out to form a hard, inflexible material that, when rewetted, will putrefy, while tanned material dries to a flexible form that does not become putrid when rewetted.

Many tanning methods and materials exist. The typical process sees tanners load the hides into a drum and immerse them in a tank that contains the tanning "liquor". The hides soak while the drum slowly rotates about its axis, and the tanning liquor slowly penetrates through the full thickness of the hide. Once the process achieves even penetration, workers slowly raise the liquor's pH in a process called basification, which fixes the tanning material to the leather. The more tanning material fixed, the higher the leather's hydrothermal stability and shrinkage temperature resistance.

Crusting is a process that thins and lubricates leather. It often includes a coloring operation. Chemicals added during crusting must be fixed in place. Crusting culminates with a drying and softening operation, and may include splitting, shaving, dyeing, whitening or other methods.

For some leathers, tanners apply a surface coating, called "finishing". Finishing operations can include oiling, brushing, buffing, coating, polishing, embossing, glazing, or tumbling, among others.

Leather can be oiled to improve its water resistance. This currying process after tanning supplements the natural oils remaining in the leather itself, which can be washed out through repeated exposure to water. Frequent oiling of leather, with mink oil, neatsfoot oil, or a similar material keeps it supple and improves its lifespan dramatically.

Tanning methods

Tanning processes largely differ in which chemicals are used in the tanning liquor. Some common types include:

• Vegetable-tanned leather is tanned using tannins extracted from vegetable matter, such as tree bark prepared in bark mills. It is the oldest known method. It is supple and light brown in color, with the exact shade depending on the mix of materials and the color of the skin. The color tan derives its name from the appearance of undyed vegetable-tanned leather. Vegetable-tanned leather is not stable in water; it tends to discolor, and if left to soak and then dry, it shrinks and becomes harder. This is a feature of vegetable-tanned leather that is exploited in traditional shoemaking. In hot water, it shrinks drastically and partly congeals, becoming rigid and eventually brittle. Boiled leather is an example of this, where the leather has been hardened by being immersed in hot water, or in boiled wax or similar substances. Historically, it was occasionally used as armor after hardening, and it has also been used for book binding.
• Chrome-tanned leather, invented in 1858, is tanned using chromium sulfate and other chromium salts . It is also known as "wet blue" for the pale blue color of the undyed leather. The chrome tanning method usually takes approximately one day to complete, making it best suited for large-scale industrial use. This is the most common method in modern use. It is more supple and pliable than vegetable-tanned leather and does not discolor or lose shape as drastically in water as vegetable-tanned. However, there are environmental concerns with this tanning method, as chromium is a heavy metal.
• Aldehyde-tanned leather is tanned using glutaraldehyde or oxazolidine compounds. It is referred to as "wet white" due to its pale cream color. It is the main type of "chrome-free" leather, often seen in shoes for infants and automobiles. Formaldehyde has been used for tanning in the past; it is being phased out due to danger to workers and sensitivity of many people to formaldehyde.
  • Chamois leather is a form of aldehyde tanning that produces a porous and highly water-absorbent leather. Chamois leather is made using marine oils (traditionally cod oil) that oxidize to produce the aldehydes that tan the leather.
• Brain tanned leathers are made by a labor-intensive process that uses emulsified oils, often those of animal brains such as deer, cattle, and buffalo. They are known for their exceptional softness and washability.
• Alum leather is transformed using aluminium salts mixed with a variety of binders and protein sources, such as flour and egg yolk. Alum leather is not actually tanned; rather the process is called "tawing", and the resulting material reverts to rawhide if soaked in water long enough to remove the alum salts.

Grades

In general, leather is produced in the following grades:

• Top-grain leather includes the outer layer of the hide, known as the grain, which features finer, more densely packed fibers, resulting in strength and durability. Depending on thickness, it may also contain some of the more fibrous under layer, known as the corium. Types of top-grain leather include:
  • Full-grain leather contains the entire grain layer, without any removal of the surface. Rather than wearing out, it develops a patina during its useful lifetime. It is usually considered the highest quality leather. Furniture and footwear are often made from full-grain leather. Full-grain leather is typically finished with a soluble aniline dye. Russia leather is a form of full-grain leather.
  • Corrected grain leather has the surface subjected to finishing treatments to create a more uniform appearance. This usually involves buffing or sanding away flaws in the grain, then dyeing and embossing the surface.
  • Nubuck is top-grain leather that has been sanded or buffed on the grain side to give a slight nap of short protein fibers, producing a velvet-like surface.
• Split leather is created from the corium left once the top-grain has been separated from the hide, known as the drop split. In thicker hides, the drop split can be further split into a middle split and a flesh split.
  • Suede is made from the underside of a split to create a soft, napped finish. It is often made from younger or smaller animals, as the skins of adults often result in a coarse, shaggy nap.
  • Bicast leather is split leather that has a polyurethane or vinyl layer applied to the surface and embossed to give it the appearance of a grain. It is slightly stiffer than top-grain leather but has a more consistent texture.
  • Patent leather is leather that has been given a high-gloss finish by the addition of a coating. Dating to the late 1700s, it became widely popular after inventor Seth Boyden developed the first mass-production process, using a linseed-oil-based lacquer, in 1818. Modern versions are usually a form of bicast leather.
• Bonded leather, also called reconstituted leather, is a material that uses leather scraps that are shredded and bonded together with polyurethane or latex onto a fiber mesh. The amount of leather fibers in the mix varies from 10% to 90%, affecting the properties of the product.

From other animals

Phone cases in ostrich leather

 

Today, most leather is made of cattle hides, which constitute about 65% of all leather produced. Other animals that are used include sheep, about 13%, goats, about 11%, and pigs, about 10%. Obtaining accurate figures from around the world is difficult, especially for areas where the skin may be eaten. Other animals mentioned below only constitute a fraction of a percent of total leather production.

Horse hides are used to make particularly durable leathers. Shell cordovan is a horse leather made not from the outer skin but an under layer found only in equine species called the shell. It is prized for its mirror-like finish and anti-creasing properties.

Lamb and deerskin are used for soft leather in more expensive apparel. Deerskin is widely used in work gloves and indoor shoes.

Reptilian skins, such as alligator, crocodile, and snake, are noted for their distinct patterns that reflect the scales of their species. This has led to hunting and farming of these species in part for their skins.

Kangaroo leather is used to make items that must be strong and flexible. It is the material most commonly used in bullwhips. Some motorcyclists favor kangaroo leather for motorcycle leathers because of its light weight and abrasion resistance. Kangaroo leather is also used for falconry jesses, soccer footwear, and boxing speed bags.

Although originally raised for their feathers in the 19th century, ostriches are now more popular for both meat and leather. Ostrich leather has a characteristic "goose bump" look because of the large follicles where the feathers grew. Different processes produce different finishes for many applications, including upholstery, footwear, automotive products, accessories, and clothing.

In Thailand, stingray leather is used in wallets and belts. Stingray leather is tough and durable. The leather is often dyed black and covered with tiny round bumps in the natural pattern of the back ridge of an animal. These bumps are then usually dyed white to highlight the decoration. Stingray rawhide is also used as grips on Chinese swords, Scottish basket hilted swords, and Japanese katanas. Stingray leather is also used for high abrasion areas in motorcycle racing leathers (especially in gloves, where its high abrasion resistance helps prevent wear through in the event of an accident.)

For a given thickness, fish leather is typically much stronger due to its criss-crossed fibers.

Environmental impact

Leather produces some environmental impact, most notably due to:

• The carbon footprint of cattle rearing
• Use of chemicals in the tanning process (e.g., chromium, phthalate esters, nonyl phenol ethoxylate soaps, pentachlorophenol and solvents)
• Air pollution due to the transformation process (hydrogen sulfide is formed during mixing with acids and ammonia liberated during deliming, solvent vapors)

Carbon footprint

One estimate of the carbon footprint of leather goods is 0.51 kg of CO₂ equivalent per £1 of output at 2010 retail prices, or 0.71 kg CO₂eq per £1 of output at 2010 industry prices.

Water footprint

One ton of hide or skin generally produces 20 to 80 m³ of waste water, including chromium levels of 100–400 mg/l, sulfide levels of 200–800 mg/l, high levels of fat and other solid wastes, and notable pathogen contamination. Producers often add pesticides to protect hides during transport. With solid wastes representing up to 70% of the wet weight of the original hides, the tanning process represents a considerable strain on water treatment installations.

Disposal

Leather biodegrades slowly—taking 25 to 40 years to decompose. However, vinyl and petrochemical-derived materials take 500 or more years to decompose.

Chemical waste disposal

Rajasthani-style leather jooti, Jaipur, India

 

Tanning is especially polluting in countries where environmental regulations are lax, such as in India, the world's third-largest producer and exporter of leather. To give an example of an efficient pollution prevention system, chromium loads per produced tonne are generally abated from 8 kg to 1.5 kg. VOC emissions are typically reduced from 30 kg/t to 2 kg/t in a properly managed facility. A review of the total pollution load decrease achievable according to the United Nations Industrial Development Organization posts precise data on the abatement achievable through industrially proven low-waste advanced methods, while noting, "even though the chrome pollution load can be decreased by 94% on introducing advanced technologies, the minimum residual load 0.15 kg/t raw hide can still cause difficulties when using landfills and composting sludge from wastewater treatment on account of the regulations currently in force in some countries." 

In Kanpur, the self-proclaimed "Leather City of World"—with 10,000 tanneries as of 2011 and a city of three million on the banks of the Ganges—pollution levels were so high, that despite an industry crisis, the pollution control board decided to shut down 49 high-polluting tanneries out of 404 in July 2009. In 2003 for instance, the main tanneries' effluent disposal unit was dumping 22 tonnes of chromium-laden solid waste per day in the open.

In the Hazaribagh neighborhood of Dhaka in Bangladesh, chemicals from tanneries end up in Dhaka's main river. Besides the environmental damage, the health of both local factory workers and the end consumer is also negatively affected. After approximately 15 years of ignoring high court rulings, the government shut down more than 100 tanneries the weekend of 8 April 2017 in the neighborhood.

The higher cost associated with the treatment of effluents than to untreated effluent discharging leads to illegal dumping to save on costs. For instance, in Croatia in 2001, proper pollution abatement cost US$70–100 per ton of raw hides processed against $43/t for irresponsible behavior. In November 2009, one of Uganda's main leather making companies was caught directly dumping waste water into a wetland adjacent to Lake Victoria.

Role of enzymes

Enzymes like proteases, lipases, and amylases have an important role in the soaking, dehairing, degreasing, and bating operations of leather manufacturing. Proteases are the most commonly used enzymes in leather production. The enzyme must not damage or dissolve collagen or keratin, but should hydrolyze casein, elastin, albumin, globulin-like proteins, and nonstructural proteins that are not essential for leather making. This process is called bating.

Lipases are used in the degreasing operation to hydrolyze fat particles embedded in the skin.

Amylases are used to soften skin, to bring out the grain, and to impart strength and flexibility to the skin. These enzymes are rarely used.

Preservation and conditioning

The natural fibers of leather break down with the passage of time. Acidic leathers are particularly vulnerable to red rot, which causes powdering of the surface and a change in consistency. Damage from red rot is aggravated by high temperatures and relative humidities. Although it is chemically irreversible, treatments can add handling strength and prevent disintegration of red rotted leather.

Exposure to long periods of low relative humidities (below 40%) can cause leather to become desiccated, irreversibly changing the fibrous structure of the leather. Chemical damage can also occur from exposure to environmental factors, including ultraviolet light, ozone, acid from sulfurous and nitrous pollutants in the air, or through a chemical action following any treatment with tallow or oil compounds. Both oxidation and chemical damage occur faster at higher temperatures.

Various treatments are available such as conditioners. Saddle soap is used for cleaning, conditioning, and softening leather. Leather shoes are widely conditioned with shoe polish.

In modern culture

Due to its excellent resistance to abrasion and wind, leather found a use in rugged occupations. The enduring image of a cowboy in leather chaps gave way to the leather-jacketed and leather-helmeted aviator. When motorcycles were invented, some riders took to wearing heavy leather jackets to protect from road rash and wind blast; some also wear chaps or full leather pants to protect the lower body. 

Leather's flexibility allows it to be formed and shaped into balls and protective gear. Subsequently, many sports use equipment made from leather, such as baseball gloves and the ball used in American football. 

Leather fetishism is the name popularly used to describe a fetishistic attraction to people wearing leather, or in certain cases, to the garments themselves.

Many rock groups (particularly heavy metal and punk groups in the 1980s) are well known for wearing leather clothing. Extreme metal bands (especially black metal bands) and Goth rock groups have extensive black leather clothing. Leather has become less common in the punk community over the last three decades, as there is opposition to the use of leather from punks who support animal rights. 

Many cars and trucks come with optional or standard leather or "leather faced" seating.

Religious sensitivities

In countries with significant populations of individuals observing religions which place restrictions on material choices, leather vendors typically clarify the kinds of leather in their products. For example, leather shoes bear a label that identifies the animal from which the leather came. This helps a Muslim not accidentally purchase pigskin, and a Hindu to avoid cattleskin, this is to adhere to religious observance and respect. Many vegetarian Hindus do not use any kind of leather. Such taboos increase the demand for religiously neutral leathers such as ostrich and deer.

Judaism forbids the comfort of wearing leather shoes on Yom Kippur, Tisha B'Av, and during mourning.

Jainism prohibits the use of leather, since it is obtained by killing animals.

Alternatives

Many forms of artificial leather have been developed, usually involving polyurethane or vinyl coatings applied to a cloth backing. Many names and brands for such artificial leathers exist, including "pleather", a portmanteau of "plastic leather", and the brand name Naugahyde.

Another alternative is cultured leather which is lab-grown using cell culture methods.

Textile industry

From Wikipedia, the free encyclopedia

 

An old textile factory ("Cvernovka") in Bratislava, Slovakia (1901-2004).

 

Textile factory (Germany, c. 1975).

 

The textile industry is primarily concerned with the design, production and distribution of yarn, cloth and clothing. The raw material may be natural, or synthetic using products of the chemical industry.

Industry process

Cotton manufacturing

Cotton is the world's most important natural fibre. In the year 2007, the global yield was 25 million tons from 35 million hectares cultivated in more than 50 countries. There are five stages:

• Cultivating and Harvesting
• Preparatory Processes
• Spinning — giving yarn
• Weaving — giving fabrics 
• Finishing — giving textiles

Synthetic fibres

Artificial fibres can be made by extruding a polymer, through a spinneret into a medium where it hardens. Wet spinning (rayon) uses a coagulating medium. In dry spinning (acetate and triacetate), the polymer is contained in a solvent that evaporates in the heated exit chamber. In melt spinning (nylons and polyesters) the extruded polymer is cooled in gas or air and then sets. All these fibres will be of great length, often kilometres long.

Artificial fibres can be processed as long fibres or batched and cut so they can be processed like a natural fibre.

Natural fibres

Natural fibres are either from animals (sheep, goat, rabbit, silk-worm) mineral (asbestos) or from plants (cotton, flax, sisal). These vegetable fibres can come from the seed (cotton), the stem (known as bast fibres: flax, hemp, jute) or the leaf (sisal). Without exception, many processes are needed before a clean even staple is obtained- each with a specific name. With the exception of silk, each of these fibres is short, being only centimeters in length, and each has a rough surface that enables it to bond with similar staples.

History

Cottage stage

There are some indications that weaving was already known in the Palaeolithic. An indistinct textile impression has been found at Pavlov, Moravia. Neolithic textiles were found in pile dwellings excavations in Switzerland and at El Fayum, Egypt at a site which dates to about 5000 BC. 

In Roman times, wool, linen and leather clothed the European population, and silk, imported along the Silk Road from China, was an extravagant luxury. The use of flax fiber in the manufacturing of cloth in Northern Europe dates back to Neolithic times.

During the late medieval period, cotton began to be imported into Northern Europe. Without any knowledge of what it came from, other than that it was a plant, noting its similarities to wool, people in the region could only imagine that cotton must be produced by plant-borne sheep. John Mandeville, writing in 1350, stated as fact the now-preposterous belief: "There grew in India a wonderful tree which bore tiny lambs on the edges of its branches. These branches were so pliable that they bent down to allow the lambs to feed when they are hungry." This aspect is retained in the name for cotton in many European languages, such as German Baumwolle, which translates as "tree wool". By the end of the 16th century, cotton was cultivated throughout the warmer regions of Asia and the Americas.

The main steps in the production of cloth are producing the fibre, preparing it, converting it to yarn, converting yarn to cloth, and then finishing the cloth. The cloth is then taken to the manufacturer of garments. The preparation of the fibres differs the most, depending on the fibre used. Flax requires retting and dressing, while wool requires carding and washing. The spinning and weaving processes are very similar between fibers, however.

Spinning evolved from twisting the fibers by hand, to using a drop spindle, to using a spinning wheel. Spindles or parts of them have been found in archaeological sites and may represent one of the first pieces of technology available. The spinning wheel was most likely invented in the Islamic world by the 11th century.

India

A woman in Dhaka clad in fine Bengali muslin, 18th century.

 

Up until the 18th century, Mughal Empire was the most important center of manufacturing in international trade. Up until 1750, India produced about 25% of the world's industrial output. The largest manufacturing industry in Mughal Empire (16th to 18th centuries) was textile manufacturing, particularly cotton textile manufacturing, which included the production of piece goods, calicos, and muslins, available unbleached and in a variety of colours. The cotton textile industry was responsible for a large part of the empire's international trade. Bengal had a 25% share of the global textile trade in the early 18th century. Bengal cotton textiles were the most important manufactured goods in world trade in the 18th century, consumed across the world from the Americas to Japan. The most important center of cotton production was the Bengal Subah province, particularly around its capital city of Dhaka.

Bengal accounted for more than 50% of textiles and around 80% of silks imported by the Dutch from Asia and marketed it to the world, Bengali silk and cotton textiles were exported in large quantities to Europe, Asia, and Japan, and Bengali muslin textiles from Dhaka were sold in Central Asia, where they were known as "daka" textiles. Indian textiles dominated the Indian Ocean trade for centuries, were sold in the Atlantic Ocean trade, and had a 38% share of the West African trade in the early 18th century, while Bengal calicos were major force in Europe, and Bengal textiles accounted for 30% of total English trade with Southern Europe in the early 18th century.

In early modern Europe, there was significant demand for textiles from The Mughal Empire, including cotton textiles and silk products. European fashion, for example, became increasingly dependent on textiles and silks imported from The Mughal Empire. In the late 17th and early 18th centuries, The Mughal Empire accounted for 95% of British imports from Asia.

Britain

The key British industry at the beginning of the 18th century was the production of textiles made with wool from the large sheep-farming areas in the Midlands and across the country (created as a result of land-clearance and enclosure). This was a labour-intensive activity providing employment throughout Britain, with major centres being the West Country; Norwich and environs; and the West Riding of Yorkshire. The export trade in woolen goods accounted for more than a quarter of British exports during most of the 18th century, doubling between 1701 and 1770.

Exports by the cotton industry – centered in Lancashire – had grown tenfold during this time, but still accounted for only a tenth of the value of the woolen trade. Before the 17th century, the manufacture of goods was performed on a limited scale by individual workers, usually on their own premises (such as weavers' cottages). Goods were transported around the country by clothiers who visited the village with their trains of packhorses. Some of the cloth was made into clothes for people living in the same area, and a large amount of cloth was exported. River navigations were constructed, and some contour-following canals. In the early 18th century, artisans were inventing ways to become more productive. Silk, wool, fustian, and linen were being eclipsed by cotton, which was becoming the most important textile. This set the foundations for the changes.

Industrial revolution

The woven fabric portion of the textile industry grew out of the industrial revolution in the 18th century as mass production of yarn and cloth became a mainstream industry.

In 1734 in Bury, Lancashire John Kay invented the flying shuttle — one of the first of a series of inventions associated with the cotton woven fabric industry. The flying shuttle increased the width of cotton cloth and speed of production of a single weaver at a loom. Resistance by workers to the perceived threat to jobs delayed the widespread introduction of this technology, even though the higher rate of production generated an increased demand for spun cotton.

Shuttles

 

In 1761, the Duke of Bridgewater's canal connected Manchester to the coal fields of Worsley and in 1762, Matthew Boulton opened the Soho Foundry engineering works in Handsworth, Birmingham. His partnership with Scottish engineer James Watt resulted, in 1775, in the commercial production of the more efficient Watt steam engine which used a separate condenser.

In 1764, James Hargreaves is credited as inventor of the spinning jenny which multiplied the spun thread production capacity of a single worker — initially eightfold and subsequently much further. Others credit the invention to Thomas Highs. Industrial unrest and a failure to patent the invention until 1770 forced Hargreaves from Blackburn, but his lack of protection of the idea allowed the concept to be exploited by others. As a result, there were over 20,000 spinning jennies in use by the time of his death. Also in 1764, Thorp Mill, the first water-powered cotton mill in the world was constructed at Royton, Lancashire, and was used for carding cotton. With the spinning and weaving process now mechanized, cotton mills cropped up all over the North West of England.

The stocking frame invented in 1589 for silk became viable when in 1759, Jedediah Strutt introduced an attachment for the frame which produced what became known as the Derby Rib, that produced a knit and purl stitch. This allowed stockings to be manufactured in silk and later in cotton. In 1768, Hammond modified the stocking frame to weave weft-knitted openworks or nets by crossing over the loops, using a mobile tickler bar- this led in 1781 to Thomas Frost's square net. Cotton had been too coarse for lace, but by 1805 Houldsworths of Manchester were producing reliable 300 count cotton thread.

19th-century developments

With the Cartwright Loom, the Spinning Mule and the Boulton & Watt steam engine, the pieces were in place to build a mechanised woven fabric textile industry. From this point there were no new inventions, but a continuous improvement in technology as the mill-owner strove to reduce cost and improve quality. Developments in the transport infrastructure; that is the canals and after 1831 the railways facilitated the import of raw materials and export of finished cloth.

Firstly, the use of water power to drive mills was supplemented by steam driven water pumps, and then superseded completely by the steam engines. For example, Samuel Greg joined his uncle's firm of textile merchants, and, on taking over the company in 1782, he sought out a site to establish a mill.Quarry Bank Mill was built on the River Bollin at Styal in Cheshire. It was initially powered by a water wheel, but installed steam engines in 1810. Quarry Bank Mill in Cheshire still exists as a well-preserved museum, having been in use from its construction in 1784 until 1959. It also illustrates how the mill owners exploited child labour, taking orphans from nearby Manchester to work the cotton. It shows that these children were housed, clothed, fed and provided with some education. In 1830, the average power of a mill engine was 48 hp, but Quarry Bank mill installed a new 100 hp water wheel. William Fairbairn addressed the problem of line-shafting and was responsible for improving the efficiency of the mill. In 1815 he replaced the wooden turning shafts that drove the machines at 50rpm, to wrought iron shafting working at 250 rpm, these were a third of the weight of the previous ones and absorbed less power.

A Roberts loom in a weaving shed in 1835. Note the wrought iron shafting, fixed to the cast iron columns

 

Secondly, in 1830, using an 1822 patent, Richard Roberts manufactured the first loom with a cast iron frame, the Roberts Loom. In 1842 James Bullough and William Kenworthy, made the Lancashire Loom, a semiautomatic power loom: although it is self-acting, it has to be stopped to recharge empty shuttles. It was the mainstay of the Lancashire cotton industry for a century, until the Northrop Loom (invented in 1894, with an automatic weft replenishment function) gained ascendancy.

Roberts self-acting mule with quadrant gearing

 

Thirdly, also in 1830, Richard Roberts patented the first self-acting mule. Stalybridge mule spinners strike was in 1824; this stimulated research into the problem of applying power to the winding stroke of the mule. The draw while spinning had been assisted by power, but the push of the wind had been done manually by the spinner, the mule could be operated by semiskilled labor. Before 1830, the spinner would operate a partially powered mule with a maximum of 400 spindles; after, self-acting mules with up to 1300 spindles could be built.

Number of looms in the UK

Year	1803	1820	1829	1833	1857
Looms	2400	14650	55500	100000	250000

The industrial revolution changed the nature of work and society The three key drivers in these changes were textile manufacturing, iron founding and steam power. The geographical focus of textile manufacture in Britain was Manchester and the small towns of the Pennines and southern Lancashire. 

Textile production in England peaked in 1926, and as mills were decommissioned, many of the scrapped mules and looms were bought up and reinstated in India.

20th century

Textile factory workers in Poland, 1950s

 

Major changes came to the textile industry during the 20th century, with continuing technological innovations in machinery, synthetic fibre, logistics, and globalization of the business. The business model that had dominated the industry for centuries was to change radically. Cotton and wool producers were not the only source for fibres, as chemical companies created new synthetic fibres that had superior qualities for many uses, such as rayon, invented in 1910, and DuPont's nylon, invented in 1935 as in inexpensive silk substitute, and used for products ranging from women's stockings to tooth brushes and military parachutes. 

The variety of synthetic fibres used in manufacturing fibre grew steadily throughout the 20th century. In the 1920s, the computer was invented; in the 1940s, acetate, modacrylic, metal fibres, and saran were developed; acrylic, polyester, and spandex were introduced in the 1950s. Polyester became hugely popular in the apparel market, and by the late 1970s, more polyester was sold in the United States than cotton.

By the late 1980s, the apparel segment was no longer the largest market for fibre products, with industrial and home furnishings together representing a larger proportion of the fibre market. Industry integration and global manufacturing led to many small firms closing for good during the 1970s and 1980s in the United States; during those decades, 95 percent of the looms in North Carolina, South Carolina and Georgia shut down, and Alabama and Virginia also saw many factories close.

The largest exporters of textiles in 2013 were China ($274 billion), India ($40 billion), Italy ($36 billion), Germany ($35 billion), Bangladesh ($28 billion) and Pakistan ($27 Billion).

Pakistan

The textile sector accounts for 70% of Pakistan's exports, but the working conditions of workers are deplorable. Small manufacturing workshops generally do not sign employment contracts, do not respect the minimum wage and sometimes employ children. Violations of labour law also occur among major subcontractors of international brands, where workers may be beaten, insulted by their superiors or paid below the minimum wage. Factories do not comply with safety standards, leading to accidents: in 2012, 255 workers died in a fire at a Karachi factory. With 547 labour inspectors in Pakistan supervising the country's 300,000 factories, the textile industry is out of control. Nor are workers protected by trade unions, which are prohibited in industrial export zones. Elsewhere, "workers involved in the creation of trade unions are victims of violence, intimidation, threats or dismissals".

Bangladesh

Many Western multinationals use labour in Bangladesh, which is one of the cheapest in the world: 30 euros per month compared to 150 or 200 in China. Four days is enough for the CEO of one of the top five global textile brands to earn what a Bangladeshi garment worker will earn in her lifetime. In April 2013, at least 1,135 textile workers died in the collapse of their factory. Other fatal accidents due to unsanitary factories have affected Bangladesh: in 2005 a factory collapsed and caused the death of 64 people. In 2006, a series of fires killed 85 people and injured 207 others. In 2010, some 30 people died of asphyxiation and burns in two serious fires.

In 2006, tens of thousands of workers mobilized in one of the country's largest strike movements, affecting almost all of the 4,000 factories. The Bangladesh Garment Manufacturers and Exporters Association (BGMEA) uses police forces to crack down. Three workers were killed, hundreds more were wounded by bullets, or imprisoned. In 2010, after a new strike movement, nearly 1,000 people were injured among workers as a result of the repression.

Ethiopia

Employees of Ethiopian garment factories, who work for brands such as Guess, H&M or Calvin Klein, receive a monthly salary of 26 dollars per month. These very low wages have led to low productivity, frequent strikes and high turnover. Some factories have replaced all their employees on average every 12 months, according to the 2019 report of the Stern Centre for Business and Human Rights at New York University.

The report states:" Rather than the docile and cheap labour force promoted in Ethiopia, foreign-based suppliers have met employees who are unhappy with their pay and living conditions and who want to protest more and more by stopping work or even quitting. In their eagerness to create a "made in Ethiopia" brand, the government, global brands and foreign manufacturers did not anticipate that the base salary was simply too low for workers to make a living from.

Commerce and regulation

The Multi Fibre Arrangement (MFA) governed the world trade in textiles and garments from 1974 through 2004, imposing quotas on the amount developing countries could export to developed countries. It expired on 1 January 2005.

The MFA was introduced in 1974 as a short-term measure intended to allow developed countries to adjust to imports from the developing world. Developing countries have a natural advantage in textile production because it is labor-intensive and they have low labor costs. According to a World Bank/International Monetary Fund (IMF) study, the system has cost the developing world 27 million jobs and $40 billion a year in lost exports.

However, the Arrangement was not negative for all developing countries. For example, the European Union (EU) imposed no restrictions or duties on imports from the very poor countries, such as Bangladesh, leading to a massive expansion of the industry there. 

At the General Agreement on Tariffs and Trade (GATT) Uruguay Round, it was decided to bring the textile trade under the jurisdiction of the World Trade Organization (WTO). The WTO Agreement on Textiles and Clothing provided for the gradual dismantling of the quotas that existed under the MFA. This process was completed on 1 January 2005. However, large tariffs remain in place on many textile products.

Women work in a textile factory outside Dhaka, Bangladesh.

 

Bangladesh was expected to suffer the most from the ending of the MFA, as it was expected to face more competition, particularly from China. However, this was not the case. It turns out that even in the face of other economic giants, Bangladesh's labor is “cheaper than anywhere else in the world.” While some smaller factories were documented making pay cuts and layoffs, most downsizing was essentially speculative – the orders for goods kept coming even after the MFA expired. In fact, Bangladesh's exports increased in value by about $500 million in 2006.

Regulatory standards

For textiles, like for many other products, there are certain national and international standards and regulations that need to be complied with to ensure quality, safety and sustainability.

The following standards amongst others apply to textiles:

CPSIA, e.g. Standard for the Flammability of Clothing Textiles

• ASTM Textile Standards
• REACH Regulations for Textiles
• China Product Standard for Textiles

Fiber

From Wikipedia, the free encyclopedia

 

A bundle of optical fibers

 

Fiber (or fibre in British English, see spelling differences; from the Latin fibra) is a natural or synthetic substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate fibers, for example carbon fiber and ultra-high-molecular-weight polyethylene. 

Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but for clothing natural fibers can give some benefits, such as comfort, over their synthetic counterparts.

Natural fibers

Natural fibers develop or occur in the fiber shape, and include those produced by plants, animals, and geological processes. They can be classified according to their origin:

• Vegetable fibers are generally based on arrangements of cellulose, often with lignin: examples include cotton, hemp, jute, flax, ramie, sisal, bagasse, and banana. Plant fibers are employed in the manufacture of paper and textile (cloth), and dietary fiber is an important component of human nutrition.
• Wood fiber, distinguished from vegetable fiber, is from tree sources. Forms include groundwood, lacebark, thermomechanical pulp (TMP), and bleached or unbleached kraft or sulfite pulps. Kraft and sulfite (also called sulphite) refer to the type of pulping process used to remove the lignin bonding the original wood structure, thus freeing the fibers for use in paper and engineered wood products such as fiberboard.
• Animal fibers consist largely of particular proteins. Instances are silkworm silk, spider silk, sinew, catgut, wool, sea silk and hair such as cashmere wool, mohair and angora, fur such as sheepskin, rabbit, mink, fox, beaver, etc.
• Mineral fibers include the asbestos group. Asbestos is the only naturally occurring long mineral fiber. Six minerals have been classified as "asbestos" including chrysotile of the serpentine class and those belonging to the amphibole class: amosite, crocidolite, tremolite, anthophyllite and actinolite. Short, fiber-like minerals include wollastonite and palygorskite.
• Biological fibers also known as fibrous proteins or protein filaments consist largely of biologically relevant and biologically very important proteins, mutations or other genetic defects can lead to severe diseases. Instances are collagen family of proteins, tendon, muscle proteins like actin, cell proteins like microtubules and many others, spider silk, sinew and hair etc.

Man-made fibers

Man-made or chemical fibers are fibers whose chemical composition, structure, and properties are significantly modified during the manufacturing process. Man-made fibers consist of regenerated fibers and synthetic fibers.

Semi-synthetic fibers

Semi-synthetic fibers are made from raw materials with naturally long-chain polymer structure and are only modified and partially degraded by chemical processes, in contrast to completely synthetic fibers such as nylon (polyamide) or dacron (polyester), which the chemist synthesizes from low-molecular weight compounds by polymerization (chain-building) reactions. The earliest semi-synthetic fiber is the cellulose regenerated fiber, rayon. Most semi-synthetic fibers are cellulose regenerated fibers.

Cellulose regenerated fibers

Cellulose fibers are a subset of man-made fibers, regenerated from natural cellulose. The cellulose comes from various sources: rayon from tree wood fiber, bamboo fiber from bamboo, seacell from seaweed, etc. In the production of these fibers, the cellulose is reduced to a fairly pure form as a viscous mass and formed into fibers by extrusion through spinnerets. Therefore, the manufacturing process leaves few characteristics distinctive of the natural source material in the finished products.

Some examples of this fiber type are:

• rayon
• bamboo fiber
• Lyocell, a brand of rayon
• Modal
• diacetate fiber
• triacetate fiber.

Historically, cellulose diacetate and -triacetate were classified under the term rayon, but are now considered distinct materials.

Synthetic fibers

Synthetic come entirely from synthetic materials such as petrochemicals, unlike those man-made fibers derived from such natural substances as cellulose or protein.

Fiber classification in reinforced plastics falls into two classes: (i) short fibers, also known as discontinuous fibers, with a general aspect ratio (defined as the ratio of fiber length to diameter) between 20 and 60, and (ii) long fibers, also known as continuous fibers, the general aspect ratio is between 200 and 500.

Metallic fibers

Metallic fibers can be drawn from ductile metals such as copper, gold or silver and extruded or deposited from more brittle ones, such as nickel, aluminum, or iron.

Carbon fiber

Carbon fibers are often based on oxidized and via pyrolysis carbonized polymers like PAN, but the end product is almost pure carbon.

Silicon carbide fiber

Silicon carbide fibers, where the basic polymers are not hydrocarbons but polymers, where about 50% of the carbon atoms are replaced by silicon atoms, so-called poly-carbo-silanes. The pyrolysis yields an amorphous silicon carbide, including mostly other elements like oxygen, titanium, or aluminium, but with mechanical properties very similar to those of carbon fibers.

Fiberglass

Fiberglass, made from specific glass, and optical fiber, made from purified natural quartz, are also man-made fibers that come from natural raw materials, silica fiber, made from sodium silicate (water glass) and basalt fiber made from melted basalt.

Mineral fibers

Mineral fibers can be particularly strong because they are formed with a low number of surface defects, asbestos is a common one.

Polymer fibers

• Polymer fibers are a subset of man-made fibers, which are based on synthetic chemicals (often from petrochemical sources) rather than arising from natural materials by a purely physical process. These fibers are made from:
  • polyamide nylon
  • PET or PBT polyester
  • phenol-formaldehyde (PF)
  • polyvinyl chloride fiber (PVC) vinyon
  • polyolefins (PP and PE) olefin fiber
  • acrylic polyesters, pure polyester PAN fibers are used to make carbon fiber by roasting them in a low oxygen environment. Traditional acrylic fiber is used more often as a synthetic replacement for wool. Carbon fibers and PF fibers are noted as two resin-based fibers that are not thermoplastic, most others can be melted.
  • aromatic polyamids (aramids) such as Twaron, Kevlar and Nomex thermally degrade at high temperatures and do not melt. These fibers have strong bonding between polymer chains
  • polyethylene (PE), eventually with extremely long chains / HMPE (e.g. Dyneema or Spectra).
  • Elastomers can even be used, e.g. spandex although urethane fibers are starting to replace spandex technology.
  • polyurethane fiber
  • Elastolefin
• Coextruded fibers have two distinct polymers forming the fiber, usually as a core-sheath or side-by-side. Coated fibers exist such as nickel-coated to provide static elimination, silver-coated to provide anti-bacterial properties and aluminum-coated to provide RF deflection for radar chaff. Radar chaff is actually a spool of continuous glass tow that has been aluminum coated. An aircraft-mounted high speed cutter chops it up as it spews from a moving aircraft to confuse radar signals.

Microfibers

Microfibers in textiles refer to sub-denier fiber (such as polyester drawn to 0.5 denier). Denier and Dtex are two measurements of fiber yield based on weight and length. If the fiber density is known, you also have a fiber diameter, otherwise it is simpler to measure diameters in micrometers. Microfibers in technical fibers refer to ultra fine fibers (glass or meltblown thermoplastics) often used in filtration. Newer fiber designs include extruding fiber that splits into multiple finer fibers. Most synthetic fibers are round in cross-section, but special designs can be hollow, oval, star-shaped or trilobal. The latter design provides more optically reflective properties. Synthetic textile fibers are often crimped to provide bulk in a woven, non woven or knitted structure. Fiber surfaces can also be dull or bright. Dull surfaces reflect more light while bright tends to transmit light and make the fiber more transparent. 

Very short and/or irregular fibers have been called fibrils. Natural cellulose, such as cotton or bleached kraft, show smaller fibrils jutting out and away from the main fiber structure.

Typical properties of selected fibers

Fibers can be divided into natural and man-made (synthetic) substance, their properties can affect their performance in many applications. Nowadays, man-made fiber materials are replacing other conventional materials like glass and wood in a number of applications. This is because man-made fibers can be engineered chemically, physically, and mechanically to suit particular technical engineering. In choosing a fiber type, a manufacturer would balance their properties with the technical requirements of the applications. Various fibers are available to select for manufacturing.