How to compare fashion materials without greenwash

When people ask which fabric is most sustainable, the honest answer is usually, “Compared with what, for which product, and at which stage?” There is no single fibre that wins on every measure. Cotton, wool, viscose, polyester, leather and newer bio-based options all come with trade-offs in land use, fossil fuel use, water, chemicals, durability, shedding, animal welfare, forest risk or end-of-life.

A better way to compare sustainable fashion materials is to look at impact category by impact category, then narrow it to the actual garment in front of you. A raincoat, a T-shirt, a knit jumper and a pair of shoes do not ask the same things of a material. Nor does a fibre claim on a swing tag tell you much on its own. What matters is how the raw material was grown or made, how it was processed, where it was sourced, and whether the brand can prove any of it. If you want a wider framework for judging claims, our guide to how to judge fashion ethics in the UK sits well alongside this one.

Why one material is rarely the whole answer

Material comparison goes wrong when we expect a universal ranking. We want a neat list, best to worst. Fashion does not work like that.

Take cotton and polyester. Cotton is plant-based and biodegradable in principle, but conventional cotton can involve heavy pesticide use and irrigation stress, depending on origin and farming system. Polyester is fossil-based and sheds microfibres, but it can be hard-wearing, quick-drying and useful in products that need strength or weather resistance. Recycled polyester may reduce demand for virgin fossil feedstock, but it does not solve microfibre shedding or make a garment automatically circular.

The same applies to wool versus acrylic, or leather versus synthetic alternatives. Wool raises questions about methane, land management, mulesing and scouring chemistry. Acrylic is fossil-based and sheds microplastics, yet may be chosen for price, softness or allergy reasons. Leather uses a by-product stream from livestock, but tanning chemistry, wastewater control and animal agriculture impacts matter enormously. A plastic-based “vegan leather” avoids animal hide, but often relies on polyurethane or PVC.

The more useful comparison is by three lenses.

First, compare by impact category. Climate impact, biodiversity, water scarcity, toxicity, microplastic release, durability and repairability are not interchangeable. A material can perform relatively well in one category and poorly in another.

Second, compare by product use. A lining, outer shell, denim, knitwear, trainers and handbags have different technical demands. A fibre that is excessive for one use may be sensible for another.

Third, compare by supply-chain stage. Fibre production is only one stage. Spinning, dyeing, tanning, finishing, lamination, transport, care in use and disposal can all change the picture.

That is why broad claims such as “our fabric is the most eco-friendly” should raise an eyebrow. They flatten a chain of decisions into one easy adjective. As we have set out in our piece on why greenwashing matters in fashion and jewellery, the problem is not only exaggeration. It is also omission.

What the main fashion material groups actually involve

Natural fibres include cotton, linen, hemp, wool, cashmere, alpaca and silk. Plant fibres are grown, harvested and mechanically or chemically processed into spinnable fibre. Animal fibres come from animals that are shorn, combed or reeled, then washed, sorted and spun. The main questions here are usually farming inputs, land use, biodiversity effects, irrigation, animal welfare and the chemistry used in wet processing. Cotton often turns on irrigation and pesticides. Linen and hemp can be lower-input in some systems, but retting and processing still matter. Wool and cashmere depend heavily on grazing management, animal treatment and scour and dye processes.

Man-made cellulosics include viscose, rayon, modal, lyocell and cupro. These start with cellulose, usually wood pulp, though some use cotton linters or other plant feedstocks. The pulp is dissolved and extruded into fibres. The key issues are forest sourcing, whether ancient or endangered forests are excluded, solvent recovery rates, wastewater treatment and chemical handling. Viscose has long carried concerns about hazardous chemicals where controls are poor. Lyocell is often presented as cleaner because its solvent system can be recovered in a closed loop, but that does not remove the need to ask where the pulp came from or how the mill performs in practice.

Synthetics include polyester, polyamide or nylon, acrylic and elastane. These are generally derived from petrochemicals, though some bio-based feedstocks now exist for certain polymers. Their main issues are fossil fuel dependence, energy intensity, microfibre shedding, chemical additives and end-of-life limitations. Recycled content can improve part of the picture, especially if it displaces virgin polymer, but feedstock source matters. Bottle-derived recycled polyester is common, but textile-to-textile recycling remains limited and quality loss can be a problem. Blends with elastane or mixed fibres can make recycling harder.

Leather begins with animal hides, then passes through preservation, soaking, liming, tanning, dyeing and finishing. Chrome tanning is common and can be safe in well-run facilities, but poor wastewater and sludge management create serious risks. Vegetable tanning avoids chromium salts but is not automatically low impact, because it still uses water, energy and multiple chemicals. The big questions are whether the hide is genuinely a by-product of the meat and dairy system, what traceability exists back to farm or slaughterhouse, whether deforestation risk has been addressed, and how the tannery manages effluent and worker safety.

Newer bio-based materials cover a mixed group. Some are partly plant-derived coatings or composites. Some are lab-grown or fermentation-based materials. Some use agricultural residues, fungi or bacterial cellulose. Their appeal is obvious, but “bio-based” does not necessarily mean plastic-free, biodegradable in ordinary conditions, or available at commercial scale. Many current alternatives still rely on polyurethane binders, synthetic backings or coatings to achieve performance. The right question is not whether a material sounds futuristic. It is what percentage is actually bio-based, what the backing and finish are made from, how durable it is in use, and what happens at end of life.

How to read material claims on labels and websites

Most material claims are not entirely false. The problem is that they are often incomplete.

“Organic cotton” should mean cotton grown to an organic farming standard, with certification somewhere in the chain. For UK readers, that usually means looking for a recognised organic textile claim linked to certified fibre content and chain of custody, not simply a leaf icon or the word “organic” in a product name. Also check whether the whole garment is certified or only the cotton fibre. Trims, dyes and blends may sit outside the headline claim.

“Recycled” needs two follow-up questions. Recycled what, and how much? Pre-consumer waste and post-consumer waste are not the same. Nor is “made with recycled materials” the same as “100 per cent recycled fabric”. Brands should be able to state fibre percentage and, ideally, whether the claim is supported by a chain-of-custody standard. For more on this, see our guide to recycled polyester labels decoded for UK clothes buyers.

“Regenerative” is one of the loosest claims in fashion at the moment. It may refer to farming practices intended to improve soil health, biodiversity and water retention, but there is no single legal definition that guarantees a fixed outcome across fibres and regions. A serious regenerative claim should tell you what standard, programme or measurable practices sit behind it, over what land area, and whether the claim relates to the farm, the fibre volume, or a pilot project.

“Vegan” tells you only that the product does not contain animal-derived material, subject to the scheme or definition used. It does not tell you whether the item is plastic-based, fossil-based, recyclable, repairable or low toxicity. A polyurethane-coated bag may be vegan and still have a heavy environmental footprint. For some shoppers, animal avoidance is the main concern. For others, it is one factor among several. The label does not resolve that tension for you.

“Low impact”, “responsible”, “eco”, “planet-friendly” and similar phrases are the weakest category. In the UK, broad environmental claims fall under consumer protection rules and guidance from the Competition and Markets Authority, including the Green Claims Code. Claims should be truthful, clear, specific, and substantiated. If a label says “more sustainable”, we should be told, more sustainable than what, on which metric, and based on what evidence.

A good test is whether the claim can survive being expanded into a full sentence. “This jacket uses 65 per cent GRS-certified recycled polyester in the outer fabric, and the dyehouse meets specified wastewater criteria” is informative. “Conscious collection” is not.

What certification can and cannot prove

Certification is useful, but only if we understand scope.

For textiles, GOTS can cover organic fibre content plus restrictions on certain chemicals and social criteria in processing. It is one of the stronger standards for organic textiles, but it does not mean zero impact, and the label level matters. OCS tracks organic material content, but it is not a full environmental processing standard in the way GOTS is.

For recycled content, GRS and RCS are common. They can help verify declared recycled input and chain of custody. GRS also includes some processing and social requirements. Neither standard means the product is recyclable at end of life, nor do they solve shedding or durability issues.

For chemical management, OEKO-TEX STANDARD 100 is often misunderstood. It tests for harmful substances in the finished product within the scope of the standard. That is not the same as certifying the whole supply chain as low impact. bluesign focuses more on chemical input management and production processes in approved facilities. Again, useful, but not a complete sustainability verdict.

For forest-derived fibres such as viscose and lyocell, FSC or PEFC certification can relate to forest management and chain of custody for wood inputs. That can reduce the risk of problematic forest sourcing, but it does not by itself tell us how the fibre plant handles solvents or effluent. Some brands also use CanopyStyle-related sourcing policies to avoid ancient and endangered forests. Those policies matter, but they are not a substitute for full mill-level transparency.

For leather, Leather Working Group assesses environmental performance of tanneries, including traceability elements, chemicals and effluent management. That is valuable as far as tannery operations go. It does not certify that a leather item is low impact overall, and tannery certification does not automatically prove deforestation-free cattle supply. If a brand makes forest-risk claims linked to leather, we need to see how it traces hides back through slaughterhouses and farms, not just to a tannery.

For UK readers, one further point matters. Post-Brexit, many standards still operate across UK and EU markets, but legal enforcement on consumer claims is not identical in every detail. A certification logo may travel across borders more easily than the claim around it. We should separate the private standard from the legal marketing claim being made in the UK.

How sourcing changes the picture

Two garments made from the same fibre can have very different footprints.

Origin matters. Cotton from a rain-fed region and cotton from an irrigated water-stressed region are not equivalent. Wool from well-managed grazing land is not the same as wool from systems linked to overgrazing or poor welfare. Wood pulp from well-managed certified forests is not the same as pulp with unresolved ancient forest risk.

Processing chemistry matters too. Viscose from a facility with strong solvent recovery and effluent treatment is different from viscose made where controls are weak. Leather from a tannery with robust wastewater treatment and sludge management is different from leather processed where waste enters local waterways. Dyeing and finishing can also outweigh assumptions people make about the fibre itself.

Energy mix changes results. A mill running on a cleaner electricity grid can look very different from one using coal-heavy energy. This is one reason generic material league tables can mislead. They often average away the thing that most needs asking.

Traceability is the thread holding all this together. If a brand cannot tell you where the fibre came from, where it was spun, dyed, tanned or finished, then many of its material claims remain broad promises rather than verified facts.

A practical way to compare materials for one garment

If you are choosing between materials for a specific garment, or specifying fabric for a small collection, we suggest a simple six-step process.

First, define the product and its job. Is it a white shirt, a waterproof shell, a knit, a lining, a tote bag, a trainer upper? List the non-negotiables, such as warmth, drape, abrasion resistance, washability, stretch, weather resistance or softness.

Second, choose the impact categories that matter most for that product. For a fleece, microfibre shedding may be central. For a summer shirt, irrigation and dye chemistry may matter more than weatherproofing. For shoes or bags, durability, coating composition and repairability may outweigh fibre origin alone.

Third, compare like with like. Do not compare a heavy coated synthetic bag with an unlined cotton tote and call it a material verdict. Compare products with similar use, lifespan and performance requirements.

Fourth, ask for evidence in a short list. We look for fibre composition by percentage, country or region of origin where possible, certification names and scope, processing information such as dyehouse or tannery standards, and whether the item is mono-material or difficult-to-recycle blend. If a business cannot answer basic sourcing questions, that is part of the assessment.

Fifth, assess lifespan and care. A longer-wearing garment that is repaired, reworn and properly maintained may outperform a lower-impact fibre used in a short-lived product. This is especially relevant for outerwear, knitwear and accessories.

Sixth, write the conclusion narrowly. Instead of saying “this is the most sustainable option”, say something more precise: for this waterproof jacket, we chose a recycled synthetic shell because durability and weather performance were essential, and we prioritised verified recycled content, PFAS-free treatment where available, repairability and supplier wastewater controls. That is honest, useful and much harder to greenwash.

For shoppers, the same framework works in simpler form. Ask what the garment needs to do, what claim is being made, what proof exists, and what has been left unsaid. If the answer is still vague, move on. Better comparison usually starts with fewer adjectives and more specifics.

The point is not to become a fibre absolutist. It is to get better at reading the whole picture. That is how we compare materials without turning every label into a morality play, and without letting polished marketing stand in for evidence.