Why Blended Fabrics Are Hard to Recycle

Textile recycling stalls on one unglamorous detail: most fabric is a blend of two or more fibres, and recycling equipment wants one fibre at a time. Separating a polyester-cotton shirt back into usable polyester and usable cotton is chemistry, not sorting, and that is where the system breaks down.

Why does fibre blending break textile recycling?

Mechanical recycling shreds fabric back into loose fibre and respins it. It is cheap, widely available and reasonably efficient, but it only works properly on a clean single-fibre input. Feed it a blend and the output is a mixed fibre mass whose behaviour nobody can specify: the spinner cannot predict strength, the dyer cannot predict shade, and the resulting yarn is fit only for low-value uses such as wiping cloths or insulation.

Chemical recycling can handle blends, because it dissolves or depolymerises one component and leaves the other behind. It is also far more capital-intensive, sensitive to contamination, and available at nothing like the scale of the waste stream. That mismatch, rather than a lack of willingness, is why so much blended textile still goes to incineration or landfill.

What happens to a polycotton garment today?

Follow a standard 65/35 polyester-cotton shirt through the system. It is collected, then hand-sorted by fibre content, colour and condition. If it is wearable it is resold, which is the best outcome and delays the problem rather than solving it. If it is not wearable, sorters look at the composition label.

A pure cotton item can go to a mechanical recycler. The blend usually cannot, because the polyester content will not behave in a cotton line and the cotton content will not behave in a polyester line. It is therefore downcycled into wiping rags or shoddy fibre, or it is sent for energy recovery. Very little of it comes back as apparel fabric.

Which blends cause the most trouble?

Polyester with cotton is the highest-volume problem simply because it is everywhere. Any cellulosic-with-synthetic combination raises the same issue, including cotton with nylon and viscose with polyester.

Elastane is the disproportionate offender. It appears at only a few percent of a fabric’s weight, yet it interferes with both mechanical and chemical routes, and a few percent is enough to disqualify an otherwise recyclable garment. Coatings, laminates, bonded interlinings and heavy prints have the same disqualifying effect for the same reason: they cannot be separated economically from the fibre they sit on.

Hardware matters too. Metal rivets, mixed-polymer zips and moulded trims all have to come off before the fabric is worth anything to a recycler.

Can you tell what a fabric is made of after it is made?

Not reliably by eye, which is a large part of the problem. Composition labels are the primary sorting input, and labels get cut out, wear illegible, or are simply wrong. Manual sorters are fast but work from a limited set of cues.

Automated near-infrared sorting reads fibre composition optically and is being deployed at collection scale. It is a genuine improvement, but it has known blind spots: it struggles with very dark and black fabrics, with multi-layer constructions, and with minor components present at low percentages. Digital product identifiers carrying verified composition data are the direction of travel in European policy, and they exist precisely because the physical label is not a dependable data carrier.²

What can product teams change at the design stage?

Recyclability is decided when the specification is written, not when the product is discarded. Four decisions carry most of the weight.

Design in a single fibre wherever the performance target allows it. Where stretch is genuinely required, ask whether mechanical stretch from construction can replace elastane, and if it cannot, keep the elastane content as low as the fit tolerates. Choose mono-material trims and hardware, or fixings that come off without destroying the panel. Finally, keep the composition data attached to the product in a form that survives the label falling off.

None of this is free, and some of it costs performance. It is a trade-off to make consciously rather than by default.

Where do recycled fibres fit in the meantime?

Recycled feedstock is available now and does useful work while separation technology matures. Recycled cotton typically comes from pre-consumer cutting waste, which is clean, single-fibre and traceable, and is blended with virgin fibre to restore staple length. Recycled polyester is mostly bottle-derived rather than textile-derived, which is honest to acknowledge: it diverts packaging, it does not yet close the textile loop.

Textile-to-textile routes are the ones that actually close that loop, and recycled textile streams are growing, though volumes remain small against demand. When a supplier offers recycled content, the useful questions are what the feedstock was, what proportion of the finished fabric it represents, and what documentation backs the figure.¹

Frequently asked questions

Are blended fabrics ever recyclable?
Some are, through chemical recycling that dissolves one fibre and recovers the other. The technology works but capacity is small relative to the volume of blended textile discarded, so most blends are still downcycled or burned.

Why is elastane such a problem for recycling?
It disrupts both mechanical and chemical recycling routes even at a few percent of fabric weight. A small amount of elastane can disqualify an otherwise recyclable garment, so keeping the content minimal has an outsized effect.

Is recycled polyester made from old clothes?
Usually not. Most recycled polyester on the market is made from post-consumer beverage bottles. Textile-to-textile polyester exists but remains a small share of supply.

Does designing for recycling mean single fibre only?
It is the simplest route, but not the only one. Mono-material construction, minimal elastane, separable trims and durable composition data all improve the odds that a product can be recycled rather than downcycled.

Related materials

• Recycled Textile T2T
• Recycled Cotton
• Recycled Polyester

Tell us your performance targets and we will help you find a mono-material or recycled-content route that still meets them. Swatches, sampling and certification documentation are available through SUS Materials on request.

References

1. Circular economy analysis of textile material flows and recycling routes. ellenmacarthurfoundation.org

2. European Commission strategy for sustainable and circular textiles, covering recyclability and product information requirements. environment.ec.europa.eu