Wool

Merino’s finer fibres make it one of the softest types of wool available. A popular fabric for suits and formalwear, wool’s wicking properties make it especially suitable for outerwear. Slightly moisture-repellent and tending to retain warmth when wet, wool contains lanolin, which has antibacterial properties. 

But wool quality is far from guaranteed. The wool of any merino sheep can still be labelled merino, regardless of whether it’s reared in Spain, Australia or elsewhere. The merino label does not guarantee the fabric is100% merino wool from a merino sheep bred specifically for its wool. 

Australia is the world’s largest producer of wool. Annual production accounts for over a quarter of the world's stock. Sheep require large areas for grazing but are more profitable if kept in smaller spaces at higher densities. Higher grazing densities increase the need for the intensive use of pesticides and antibiotics which in turn lead to the contamination of surface and groundwater. Very high stock numbers lead to overgrazing, soil erosion and, in extreme cases, desertification. In New Zealand, 90% of the nation's greenhouse gas emissions arise from livestock.

The density of sheep populations means disease is often rife. Until recently, Australian farmers relied on surgical mulesing – a routine practice that involves the removal of strips of wool-bearing skin from around the buttocks of sheep to prevent blowflies laying their eggs on the sheep's skin. The most cost-effective alternative to mulesing is the breeding of ‘plain bodied’, less wrinkly merinos which are generally more resistant to flystrike. 40% of producers surveyed by Stock Journal in 2012 are breeding plainer-bodied, barer-breech sheep but 56.7% are still mulesing, as there is no viable alternative. Close to half of those still mulesing are using the pain relief drug Tri- Solfen which first became available in 2005.

In the UK, wool produced sustainably in spinning mills is becoming increasingly available: British mill production increased by 12% in 2011, and the amount of wool produced in the UK increased from 32,000 tonnes in 2009 to 40,000 tonnes in 2011, The Guardian. But this is only able to supply a fraction of the market demand.

Silk

In the 13th century, the extraordinary strength, softness and flexibility of silk made it desirable to Mongolian soldiers who found that wearing a raw silk layer made it easier to pull the points of arrows out. Silk underwear still protects soldiers’ groins and abdomens.

In medicine, silk can be used for synthetic corneas, scaffolding for broken bones, or as a conductor for ultra-thin electronics in the brain. Pound-for-pound, the strongest variety, spider silk, is, “20 times as strong as steel and four times as tough as Kevlar.” according to New Scientist. But its production is far too labour-intensive to exploit. Instead, common silk, similar in structure, is produced by the silkworm and is far more widespread.

The bulk of commercial silk farming occurs in North Asia (China, Korea and Japan), as well as India. Sericulture, the ancient method for breeding silkworms for the production of raw silk, has been practised in China for 5,000 years.

The mulberry silkworm, now completely domesticated, exists solely for this purpose and depends entirely on human cultivation. Blind, flightless, and unable to eat, no Bombyx mori moths or silkworms survive in the wild. "These things are essentially the cows of the insect world," says Chris Holland, a silk researcher at the University of Oxford. "They have been inbred to produce huge quantities of silk."

Silk farmers harvest the silk before the moths emerge from their silk cocoons to prevent damage to the thread. The few moths allowed to hatch lay around 500 eggs before dying within four or five days. A single mulberry tree can sustain 100 silkworms. One acre of mulberry trees feeds enough silkworms to produce 178 pounds of cocoons, which amounts to 35 pounds of raw silk. 

In the case of Tussah silk, produced by worms from oak or tannin-rich trees, the cocoons are collected after the moth has emerged naturally. This 'wild silk' is a darker, browner colour, like the worms’ food source, and is lumpier and less shiny than white mulberry silk. Wild silks aren’t a viable alternative for large-scale production, requiring more chemical processing and heavier dyes. 

While the environmental impact of factory-made silk is hard to ascertain, hand-woven silk can be produced on handlooms with a near zero-energy footprint. All silk is biodegradable and will decompose in landfill. 

Leather

Leather is not a by-product of the meat industry; it is a lucrative business in its own right. It also uses up a huge amount of natural resources in the breeding of animals, transportation of feed, removal of animal waste, powering of housing and killing facilities, destruction of carcasses and relocation of pelts. 

According to PETA, more than one billion cows are killed for meat each year, with the sale of the skin providing around 20% of total revenues from the individual animal. With ostrich leather, 80% of the carcass value comes from the skin and 20% from the meat. With reptile skins, almost 100% of the carcass’ value is created by the skin. 

Different types of leather offer varying aesthetic qualities. In a suspected hoax in May 2012, trainer company Rayfish footwear offered readers the chance to grow their own farmed stingray and produce a pair of leather trainers in customised colours. At the other end of the spectrum, the soft, flawless hides of calfskin are highly desirable for shoes, gloves and wallets. Given that some dairy cows are slaughtered while they are pregnant, it is possible for industry workers to remove baby calves from the mother’s carcass for their skins.

Transforming dead animal skin into a durable product is an intensive process. At the tannery, the hide is treated with chemicals—including mineral salts, formaldehyde and chemical derivatives of coal-tar —which contaminate the land, air, and water supply. At the same time, toxic gases like ammonia, hydrogen sulfide, and carcinogenic arylamines are released into the atmosphere.

The most common form of treatment is chrome tanning which can result in the cancer-causing chromium (VI) being pumped into local water supplies. In Pakistan only half of the 200 tanneries located in the Korangi Industrial Area in Karachi were processing waste sufficiently before discharging. 

Vegetable tanned leather, which uses natural tannins found in bark to colour and preserve the skins, does provide an alternative to chemical dyeing. However this only eliminates chemicals from one stage of the process. British or European leather will have been produced to high welfare and environmental standards, but of course this, and vegetable tanned leather in general, will cost more than conventional leathers.

Cashmere

Cashmere was once a luxury commodity, patented by Scottish producers and knitted into cashmere products for Pringle and Ballantyne. Now cashmere is cheaper than it has ever been.

Requiring extremely low temperatures for coat growth, cashmere goats are hard to breed outside Asia. Global supplies stand at roughly 15,000 tonnes a year – 70% of it from China. According to the Chicago Tribune, America imported 10.5 million Chinese sweaters last year, 15 times as many as ten years ago. On average, China sold its cashmere sweaters to America for just $34, a full 75% off the import price of the Scottish version. 

Grazing goats impact heavily on grasslands, consuming over 10% of their bodyweight daily in roughage, eating very close to the roots, stripping bark from seedlings, and preventing the regrowth of trees. When hungry, goats will even eat the fur of their neighbours, right down to the skin. Without grass and shrubs to hold the grassland dunes in place, the Alashan deserts are expanding by nearly 400 square miles a year. It is possible to source cashmere from goats farmed indoors, rather than on the sensitive grasslands of Inner and Outer Mongolia. In 2011, Nick Falkingham, Managing Director of British label Pure Collection, reported that 100% of the company’s cashmere was sourced via these sustainable methods. 

Shorter fibre cashmere is cheaper than a longer fibre product, but tends to produce garments that pill. Dark fibres are also cheaper but require more dye stuff, or bleaching, to alter their natural colour, which results in a scratchier texture. Although wool generally holds colour more readily then other fabrics, chrome dyes are still the standard choice for wool. Potassium dichromate, the corrosive used in the after-treatment of chrome dyes is listed as a ‘substance of very high concerns in REACH – the European Union legislation for the Registration, Evaluation and Authorisation of Chemicals.

Bamboo

Bamboo is a naturally occurring fibre and can grow nearly anywhere without pesticides or herbicides. It can’t however be broken down into fibres for clothing without the use of hazardous chemicals such as sodium hydroxide and carbon disulphide.

Tencel, sometimes referred to as lyocell, is a wood-derived, viscose-like fabric manufactured by the Austrian company Lenzing AG. The process requires a less corrosive solvent, N-methylmopholine oxide, than normal viscose production and recycles 99.6% of it each time, reducing waste. Lyocell fibres are machine-washable and can be made to simulate suede, leather, and silk. It shares many properties with other cellulosic fibres such as cotton, linen, ramie and rayon. 

Sorona is one of a number of corn-based polymers still in the pilot stages. Made by US chemical giant DuPont, Sorona uses corn as the source for part of its raw material – though more than 60% is still derived from petroleum.

Cotton

When organic clothing first hit the mainstream market in the late 1990s, organic cotton was thought to be the best option for the individual, the environment, and the workers growing and harvesting it. But the situation is changing. Organic cotton will never be a viable option for large retailers, plus the "organic" label doesn’t take into account energy and resources consumed across all phases of cotton growing, spinning and fabric manufacturing.

The oft-cited statistic, that chemical pesticide usage for conventionally grown cotton accounts for 25% of all agricultural pesticides used in the US, is now incorrect. The figure was derived from studies conducted in the 1990s, like the report from Allen Woodburn Associates Ltd entitled “Cotton: The Crop and its Agrochemicals Market” published in 1995. 

Given that cotton yields are threatened by insects, weeds, and weather, it follows that pest-resistant cotton, which is also immune to herbicides, would drastically increase farmers’ profitability whilst also driving environmental improvements. Advances in biotechnology have made this possible. The USDA reports that 87% of the US cotton crop was genetically engineered in 2007, and about 28% of the global cotton field acres were planted in transgenic GM cotton in 2005, according to The International Service for the Acquisition of Agri-biotech Applications. 

The dyeing of cotton is another ongoing concern. The indigo colour of denim jeans requires large quantities of sodium hydrosulphite which is corrosive enough to eat through cement and damage sewage pipes. Millions of litres of rinse water are used to flush out the chemicals at factories, sometimes in locations where water is already scarce.

Natural dyes, like madder, cutch, cochineal, weld, and indigo are derived from animal or plant material without any synthetic chemical treatment. But these are not necessarily any safer or more sustainable than synthetic dyes. The process still depends on harsh chemicals. Sodium hydroxide, for example, is needed to produce natural indigo dye and the extraction of madder requires the roots to be dissolved in sulphuric acid.

Leah Borromeo's documentary The Cotton Film: Dirty White Gold is in pre-production. Watch the trailer here.

Manmade Fibres

Unlike the manmade fibres viscose, acetate and cupro which are generated from chemically treated plant cellulose, polyester, nylon and acrylic are made from petroleum, a non-renewable fossil fuel, using energy intensive processes.

Nylon was first produced commercially in the 1930s, by the American chemical manufacturer DuPont, famous for its gunpowder. It was initially used for sewing thread, then women's hosiery. In wartime, it replaced silk in parachute production and became the raw material of choice for tires, tents and ropes. And it is still the world’s fabric of choice. According to industry analysts Textiles Intelligence’s 2006 study, man-made fibres, including cellulosics and synthetics, accounted for 58% of all fibre demand. Perfluorinated chemicals (PFCs) like Teflon make nylon hardy and wrinkle-free but remarkably slow to decay in landfill, which is a massive problem.

Biodegradable synthetic fibres like the corn-based Ingeo might offer a viable solution for the fashion industry. Alternatively, upcycling, where synthetic products are subjected to chemical processing and reused, could minimise landfill waste if implemented on a grand scale. The idea is that polymer-derived synthetics are least damaging when kept in an industrial loop system, which requires manufacturers to build recycling practice into production methods, as in the case of iron and aluminium.

For example, in 1994 a company called Ecolog collected their own second hand 100% polyester garments from shops, and returned the material to polyester granules, which could in turn be used for buttons and zip fasteners. Similarly in 2002 Teijin launched a synthetic recycling programme with Patagonia, removing impurities from polyester fibres and re-processing blended fabrics such as polyester and cotton. Patagonia estimates this process saves 76% in energy production when compared to virgin fabric manufacture and reduces CO2 emissions by 71% with no compromise on fabric quality.

One problem upcycling can’t tackle, however, is chemical water pollution. In a study investigating the main source of microplastic contamination on beaches in 2012, Dr Mark Anthony Brown from the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara, examined sewage-disposal sites and effluent from sewage treatment plants. The proportions of polyester and acrylic fibres in clothing matched that in effluent samples, suggesting that it’s the washing of clothes which pollutes coastlines with plastic waste. Over 1,900 fibres can wash off a single piece of clothing during a machine wash, which is more than 100 fibres per litre of effluent. 

Whether it’s possible for animals to ingest the microplastics, and for the fibres to accumulate in food chains is yet to be determined.

 Image credit: kara brugmen, wiccked, flippy whale, Michael Foley Photography, Mary Anne Thygesen, Bert van Dijk, bricoleurbanism