A guide to textile fibres: how they are made, what they cost the planet, and what the labels don't tell you.

A guide to textile fibres: how they are made, what they cost the planet, and what the labels don't tell you.

Published by Samantha, founder of Teddy Locks

 

The labels in your clothes tell you what a garment is made from. It does not tell you how that material was produced, what it consumed in the process, or what will happen to it when you throw it away.

This is a guide to the major textile fibres in common use — their production processes, their environmental profiles, and an honest comparison of where each sits. Some of these answers are more complicated than the marketing suggests. Some are simpler.

I'll work through synthetic fibres first, then natural fibres, then the alternatives that sit between them.

Polyester

Polyester is the most produced fibre in the world — 59% of global textile output in 2024, or 78 million tonnes. It is everywhere: fast fashion tops, athleisure, fleece, technical outdoor clothing, upholstery.

How it is made: Polyester is a synthetic polymer — polyethylene terephthalate, or PET — derived from petroleum. Crude oil is refined into petrochemical building blocks: terephthalic acid and ethylene glycol. These are combined through polymerisation into PET chips, which are melted and extruded through spinnerets into continuous filament or chopped into staple fibre. The process requires significant heat and pressure throughout.

The environmental cost: Producing one kilogram of virgin polyester emits approximately 5–9 kg of CO₂, depending on the energy source at the production facility. This is relatively low compared to some other fibres per kilogram, but the sheer volume produced — 78 million tonnes in 2024 — means polyester production's total emissions are enormous. Every wash of a polyester garment releases microplastic fibres — up to 700,000 per wash cycle. These pass through wastewater treatment and enter waterways and oceans, where they persist indefinitely. Synthetic textiles account for approximately 35% of primary microplastic pollution in the oceans. Polyester does not biodegrade. In landfill it fragments over centuries into smaller and smaller microplastic particles.

The recycled version: Recycled polyester — including REPREVE®, used in Teddy Locks socks — is made primarily from post-consumer plastic bottles. The bottles are collected, cleaned, shredded into flakes, melted and re-extruded into fibre. A peer-reviewed Life Cycle Assessment confirmed that REPREVE reduces greenhouse gas emissions by up to 60% and freshwater consumption by up to 67% compared to virgin polyester staple fibre. The limitation: once a polyester garment exists, whether made from virgin or recycled content, it faces the same end-of-life barriers. The microplastic problem applies to both.

 

Nylon (Polyamide)

Nylon is the second most common synthetic fibre — around 5% of global production, used primarily in hosiery, swimwear, sports performance garments, and outdoor equipment.

How it is made: Nylon is also a petroleum-derived synthetic polymer. The most common variants — nylon 6 and nylon 6,6 — are produced through different polymerisation pathways but share the same fossil fuel origin. Nylon 6,6 production is particularly problematic: it uses adipic acid, the manufacture of which produces nitrous oxide as a byproduct. Nitrous oxide is approximately 298 times more potent than CO₂ as a greenhouse gas. Modern adipic acid plants increasingly use catalytic abatement to destroy the nitrous oxide before release, but this is not universal.

The environmental cost: Producing one kilogram of nylon generates approximately 9 kg of CO₂ equivalent — broadly comparable to the higher end of polyester, higher than cotton in most methodologies. Like polyester, nylon sheds microplastics during washing and does not biodegrade. Its production also involves the use of hazardous chemicals that require careful waste management.

The recycled version: Econyl, produced by the Italian company Aquafil, is regenerated nylon made from discarded fishing nets, carpet off-cuts, and nylon fabric waste. The chemical depolymerisation process breaks nylon down to its constituent monomers and rebuilds it into virgin-equivalent fibre. Econyl carries verified lower emissions than virgin nylon and addresses a genuine waste stream — abandoned fishing nets are a significant source of ocean pollution. It is used in a growing number of swimwear and activewear brands.

 

Acrylic

Acrylic is petroleum-derived and designed to mimic the softness and warmth of wool at much lower cost. It is found in budget knitwear, blankets, carpet, and any product labelled "wool-look" at accessible price points.

How it is made: Acrylic is produced from acrylonitrile, a petrochemical compound, through polymerisation and wet or dry spinning. The production process involves toxic solvents and generates hazardous waste that requires careful management.

The environmental cost: This is genuinely bad. Producing one kilogram of acrylic generates approximately 21–36 kg of CO₂ equivalent in peer-reviewed studies — significantly higher than polyester or nylon per kilogram. Acrylic releases more microplastics per wash cycle than any other common textile fibre — around 1.5 times more than polyester. It pills rapidly, reducing garment life. It is neither biodegradable nor recyclable in any established commercial process. There is no recycled acrylic equivalent on the market at scale.

Acrylic exists because it is cheap to produce and it feels like wool. On every meaningful environmental metric, it performs worse than the synthetic fibre it competes with and worse than the natural fibre it imitates. There is no honest sustainability argument for acrylic.

 

Elastane (Spandex / Lycra)

Elastane is not a primary fibre — it is almost always present in small percentages to provide stretch. A pair of jeans might be 2% elastane. Leggings might be 20%.

How it is made: Elastane is a polyurethane-polyurea copolymer, derived from petroleum. It is produced through dry spinning of a polymer solution.

The environmental cost: Small percentages mean the direct CO₂ contribution per garment is limited. The disproportionate impact is on recyclability. Even 2% elastane in a cotton garment is enough to make mechanical recycling significantly more difficult. The elastane fibres tangle with and contaminate the cotton during pulling, reducing fibre quality. Most chemical recycling processes for cotton cannot easily handle elastane contamination. The consequence is that the overwhelming majority of stretch garments — jeans, sportswear, underwear — are effectively unrecyclable under current technology.

 

Conventional Cotton

Cotton accounts for 19% of global fibre production — 24.5 million tonnes in 2024. It is the most widely used natural fibre and has been the foundation of the global textile industry for centuries.

How it is made: Cotton is a seed fibre — the fluffy white material surrounding cotton seeds is harvested, cleaned of seeds (ginning), carded, spun into yarn and woven or knitted into fabric. It is a natural process, but not a simple one. Conventional cotton farming is heavily dependent on irrigation, synthetic pesticides, and synthetic fertilisers.

The environmental cost: Cotton's costs are concentrated at the farming stage. Conventional cotton production requires between 10,000 and 20,000 litres of water per kilogram of fibre — one of the most water-intensive crops grown anywhere. It uses approximately 4.4% of global pesticide production despite covering less than 3% of agricultural land. Carbon emissions from conventional cotton are approximately 5–7 kg CO₂e per kilogram — lower than most synthetics at point of production, but with higher land and water costs. Cotton is technically biodegradable — but as established in earlier posts, biodegradability in landfill (an anaerobic environment) produces methane rather than composting.

Organic cotton: Organic cotton avoids synthetic pesticides and fertilisers, significantly improving outcomes for farmer health, soil biology, and waterway contamination. It uses substantially less irrigation water when rain-fed. The limitations: organic certification doesn't address the water footprint where irrigation is still used, supply chains are long, and organic cotton carries a cost premium that puts it out of reach for much mainstream production.

 

 

Wool

Wool accounts for less than 1% of global fibre production. Its environmental profile is more complex than almost any other fibre — simultaneously the best and worst in different categories.

How it is made: Wool is the fleece of sheep, shorn annually. Raw wool is washed (scoured) to remove grease, lanolin and vegetable matter, carded and combed to align fibres, then spun. The process is relatively low in industrial chemical use compared to synthetic fibre production.

The environmental cost: Wool is a co-product, not a byproduct — sheep are raised for both meat and wool, not incidentally producing one while primarily producing the other. Wool's carbon footprint at production is high — approximately 4.5–6 kg CO₂e per kilogram of fibre, depending on farming system and geography. This is almost entirely due to the sheep themselves: enteric fermentation produces methane, and manure produces nitrous oxide. A single sheep produces approximately 30 litres of methane per day. 23.6% of sheep farm emissions are attributed to wool — the rest goes to meat (73.8%) and milk (2.5%). These livestock emissions account for over 75% of wool's total climate impact. Wool also requires significant land — substantially more per kilogram of output than cotton.

The critical counterpoint: wool is genuinely biodegradable, does not shed microplastics, and is the only commercially available fibre for which a functioning closed-loop recycling system exists at any meaningful scale in the UK. A wool garment worn for ten years and then mechanically recycled into new fibre has a whole-life environmental profile that compares favourably to most alternatives despite the high production emissions. Durability is the key variable. A cheap wool blend worn five times has a dreadful environmental profile. A quality merino worn for a decade does not.

 

TENCEL™ Lyocell

Lyocell sits between synthetic and natural fibres — the industry term is "regenerated cellulosic fibre" (RCF) or "man-made cellulosic fibre" (MMCF). It begins with wood (typically eucalyptus) and is transformed into fibre through a manufacturing process that is significantly cleaner than conventional viscose or bamboo processing.

How it is made: Eucalyptus trees are harvested from FSC-certified forests, pulped, and dissolved in a non-toxic solvent — N-methylmorpholine N-oxide (NMMO). The solution is extruded through spinnerets into a water bath where it solidifies into fibre. Critically, over 99% of the solvent is recovered and reused in a closed loop. The trees grow on marginal land without irrigation or pesticides.

The environmental cost: TENCEL uses up to 20 times less water than conventional cotton in production. It uses no toxic chemicals in the manufacturing step. The fibre is genuinely biodegradable in aerobic conditions — research has shown full biodegradation within 30 days in marine environments. The limitation: TENCEL fibres remain biodegradable regardless of what they are blended with, but the blended garment as a whole is not — the TENCEL portion degrades while any polyester or elastane content persists as microplastics. Most TENCEL-labelled garments contain synthetic blend components.

TENCEL is one of the most defensible material choices in sustainable fashion for garments where no synthetic blend is required. Teddy Locks socks use TENCEL alongside REPREVE — each fibre chosen for its performance function within the construction of the sock.

 

Viscose / Rayon

Viscose is also made from wood cellulose, but through a very different process to lyocell — and one with a significantly worse environmental profile.

How it is made: Wood or plant material is pulped and then dissolved in carbon disulfide — a toxic solvent — combined with sodium hydroxide to form a viscous solution. That solution is extruded through spinnerets into a sulfuric acid bath. The resulting fibre is then washed and finished. Carbon disulfide is a known neurotoxin linked to serious occupational health effects. Most viscose is produced in facilities where chemical recovery is incomplete, releasing carbon disulfide and sulfur compounds into air and water.

The environmental cost: The Changing Markets Foundation has documented widespread chemical pollution around viscose manufacturing plants, primarily in Asia. Worker exposure risks are serious in facilities without adequate controls. The fibre itself is biodegradable, but the production process carries significant chemical costs that the "natural" labelling obscures. Bamboo viscose — the most common form of bamboo fabric — is produced by this same process.

Cleaner viscose is technically achievable and is being done at a small number of facilities, but as of now that is not the norm and most viscose production globally does not meet Best Available Techniques standards.

 

Bamboo

Bamboo as a plant is genuinely remarkable. It is the world's fastest-growing woody plant — some species grow up to a metre per day under ideal conditions and reach harvestable maturity in 3–5 years, compared to 30+ years for most timber trees. It regenerates from its root system after harvesting without replanting, requires no pesticides or irrigation in most growing conditions, and is a highly effective carbon sink — research suggests bamboo forests can sequester up to 17,800 kg of CO₂ per hectare annually, outperforming many tree plantations. Unlike cotton, it does not require prime agricultural land and can grow on degraded or marginal soil. These credentials make bamboo, as a crop, one of the more compelling plant-based raw materials available.

The problem — as covered in the bamboo post — is that virtually all bamboo fabric is made via the viscose process, which transforms a genuinely sustainable plant through a chemically intensive manufacturing route that largely negates the growing-stage advantages - and why bamboo viscose from unverified sources should be treated with scepticism regardless of the bamboo plant's credentials.

 

Hemp and Linen

Hemp and linen (from flax) are among the most environmentally efficient natural fibres available. Both grow without pesticides, require minimal water (linen is largely rain-fed in European growing regions), fix nitrogen in soil, and produce fibre through low-impact mechanical processes. Their carbon footprints are among the lowest of any textile fibre.

Their limitation is performance — both are stiff, lack stretch, and require blending with other fibres for most end uses. This is why they remain niche.

 

Reading the label

When you look at a garment label, the fibre content tells you what is in it. Here is a rough guide to what that means in practice:

100% polyester or acrylic — fossil-fuel based, sheds microplastics, not recyclable, will persist in landfill for centuries. Avoid where alternatives exist.

Recycled polyester (rPET) — better than virgin on production emissions, same microplastic and end-of-life issues. A meaningful improvement, not a complete solution.

Cotton — high water and pesticide use at farming stage, biodegradable in the right conditions. Organic certification reduces farming impacts meaningfully.

Wool — high production emissions, excellent durability and recyclability, no microplastics. Value depends almost entirely on how long you keep it.

TENCEL™ lyocell — low water, closed-loop production, biodegradable when pure. Check for synthetic blend content before concluding it is clean.

Viscose / bamboo viscose — biodegradable fibre from a chemically intensive process. Better than synthetic at end of life, worse in production than lyocell.

Elastane content — even small percentages significantly reduce recyclability. The lower the elastane percentage, the better.

Blended fibres — the norm in most garments. Almost always mean the garment cannot be fibre-to-fibre recycled under current technology.

No fibre is without compromise. The question worth asking before any purchase is not "which material is best?" but "which trade-offs matter most for this specific use, and how long will I keep this?"

 

Teddy Locks socks use REPREVE® recycled polyester, TENCEL™ lyocell, recycled nylon and a small amount of spandex for stretch — each chosen deliberately for its performance role in the sock's construction. The fiber certifications — Global Recycle Standard, SCS Recycled Content Standard, Oeko-Tex Standard 100 — verify the claims we make about them.

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