Walk into any clothing store, or scroll through any brand’s website, and you’ll encounter a quiet vocabulary of materials. Cotton. Polyester. Viscose. TENCEL™. Recycled nylon. Organic linen. These words appear on care labels and product descriptions, sometimes with a small certification logo, sometimes with a brief note about sustainability.
But what do they actually mean? And more importantly: does the fibre in a garment tell us something useful about its impact?
The short answer is yes, but with more nuance than the labels might suggest. Natural doesn’t always mean better. Synthetic doesn’t always mean worse. And some of the most marketed fibres in sustainable fashion deserve a closer look.
Here is a working guide to the fabrics worth understanding.
Cotton: The Most Common, and the Most Complicated
Cotton is everywhere. It is breathable, durable, and familiar. It is also one of the most resource-intensive crops in the world.
Conventional cotton farming requires significant amounts of water. A single t-shirt can take more than 2,700 litres to produce, along with pesticides and fertilisers that affect soil health and surrounding ecosystems. The cotton industry is also linked to serious labour concerns in several major producing regions.
Organic cotton changes the equation in important ways. Certified under standards like GOTS, it prohibits synthetic pesticides and fertilisers, requires safer working conditions, and demands that processing stages meet environmental and social criteria. It still uses water, but considerably less than conventional methods, and without the chemical load.
Worth noting: “organic cotton” as a claim on a label doesn’t always mean GOTS-certified. It may refer only to the raw fibre, not the full production chain. If this distinction is new, it’s worth reading alongside Reading the Labels, which looks at what certifications actually cover.
Linen: One of the Clearest Cases
Linen, made from the flax plant, has been worn for thousands of years and its sustainability credentials hold up well under scrutiny.
Flax requires very little water beyond rainfall, minimal pesticides, and almost every part of the plant can be used. Linen fabric is naturally biodegradable and tends to soften with wear, lending itself to longevity. It is also a fibre that ages well, the kind of fabric that looks better the more it has been lived in.
Its main limitation is price. Linen is more labour-intensive to process than cotton or synthetic fibres, which makes it less common at lower price points. But for those looking for a fibre that is genuinely low-impact and long-lasting, linen is one of the clearest cases.
TENCEL™ and Lyocell: Plant-Based, Carefully Processed
TENCEL™ is a branded form of lyocell, a fibre made from wood pulp, often from sustainably managed eucalyptus forests. What makes it distinctive is its production process: lyocell is made in a closed-loop system, meaning the solvents used to break down the wood pulp are captured and reused rather than released as wastewater.
The result is a soft, breathable fabric with a lower environmental footprint than most conventional fibres. It is also biodegradable under the right conditions.
Not all lyocell carries the TENCEL™ branding, but when it does, it signals adherence to Lenzing’s specific environmental standards. It is one of the more credible innovations in sustainable textile production, and increasingly common in considered fashion brands.
Viscose and Rayon: Where “Plant-Based” Gets Complicated
Viscose (also called rayon) is another fibre derived from plant matter, typically wood pulp or bamboo. On paper, this sounds promising. In practice, the manufacturing process is often highly polluting, involving chemical solvents that can be harmful to workers and surrounding ecosystems if not carefully managed.
This is where bamboo fabric becomes a useful example. Bamboo the plant is genuinely sustainable. It grows quickly, requires no pesticides, and sequesters carbon. But most bamboo fabric on the market is processed into viscose using the same chemical-heavy method as conventional rayon. The sustainable origin story doesn’t always survive the manufacturing process.
Mechanically processed bamboo (sometimes labelled as bamboo linen) is a more environmentally sound option, but it is far less common. When you see bamboo fabric, it is worth asking how it was made.
Recycled Polyester: Better Than Virgin, But Not Without Limits
Polyester is a synthetic fibre made from petroleum. Conventional polyester is energy-intensive to produce, derived from fossil fuels, and non-biodegradable. It also sheds microplastic fibres when washed, tiny particles that pass through most water treatment systems and enter waterways.
Recycled polyester, typically made from post-consumer plastic bottles or old garments, addresses the production side of the equation. It uses significantly less energy and water than virgin polyester, and diverts plastic from landfill. For activewear and outerwear, categories where polyester’s durability and performance properties are genuinely useful, it represents a meaningful step forward.
The microplastic issue, however, remains. Recycled or not, polyester sheds when washed. A washing bag designed to capture microplastic fibres before they enter the water system is a small but practical step worth knowing about.
Wool: Natural, but Nuanced
Wool is a renewable, biodegradable natural fibre with excellent insulating properties and a long lifespan. Garments made well from quality wool can last decades.
The concerns around wool centre on animal welfare, specifically practices like mulesing used in some merino sheep farming, and broader questions about how animals are treated in commercial production. Certifications like the Responsible Wool Standard and ZQ Merino address these concerns with audited standards for animal welfare and land management.
As with other fibres, the material itself tells only part of the story. A wool jumper from a farm with strong animal welfare practices and low chemical use is a very different product from one produced under conventional farming conditions.
What This Means in Practice
No fabric is perfect. Each one involves trade-offs between water use and chemical inputs, between biodegradability and performance, between accessibility and environmental cost.
But understanding what fibres are made of, and how they are produced, gives us something more useful than a simple ranking. It gives us better questions to ask. Questions like: Is this certified organic, and what does that certification actually cover? Is this recycled, and from what? How was this processed?
The label on a garment is a starting point, not a verdict. And the more fluent we become in reading it, the more clearly we can see what we are actually choosing.
As always, this reflects my current understanding. If there are fibres you feel are missing here, or perspectives I haven’t considered, I would genuinely welcome them. There is always more to learn.