Doubling Recycled Cotton in Yarn: Recover™, Rieter and Birla Advance Circularity

Increasing recycled cotton content in highquality yarn remains one of the textile industry’s most persistent technical challenges. While mechanically recycled cotton offers clear circular benefits, its higher proportion of short fibers and neps can limit spinnability and affect yarn and fabric performance, particularly in ring spinning and finer yarn counts.

A recent collaborative trial between Recover™, Rieter and Aditya Birla Group explored a solution: replacing the conventional virgin cotton “support fiber” with a manmade cellulosic fiber (MMCF) designed to complement recycled cotton, while keeping the blend fully cellulosic and recyclable.

The challenge: why recycled cotton often hits a ceiling

In current industrial practice, many recycled‑cotton ring yarns are limited to blends of around 20% recycled cotton and 80% virgin cotton. The constraint is largely technical. Mechanically recycled cotton typically contains a higher share of short fibers, higher nep levels and greater variability in fiber length, which can reduce process stability and yarn quality. These challenges are particularly acute for ring spinning applications.

This limitation is especially evident in the case of what we call “generic recyclers” at Recover™, such as vertically integrated mills or spinners that operate recycling units as a side activity in their production processes, but lack the technical expertise in recycled fiber preparation, sorting and blend optimization, resulting in less consistent fiber quality and lower achievable recycled content.

Recover™ specializes in mechanically recycled cotton fibers and optimized blends, enabling higher recycled content than is typically achieved in the market for finished textiles from post‑industrial and post‑consumer origins, with fibers suitable for both ring and rotor spinning.

But we’re dedicated to keeping pushing the boundaries of circularity and tackling the textile waste crisis. Increasing the average recycled cotton content in finished products without compromising quality or durability remains a key focus area for research and development, which is where this trial becomes particularly relevant.

The solution: bring in cellulosic fibers with consistent length

The innovation explored in the trial is simple in concept and powerful in effect: swap the virgin cotton component for a man-made cellulosic fiber (MMCF) with consistent fiber length and then optimize the blend so recycled cotton content can increase without compromising quality.

Rieter’s report highlights a key mechanism: MMCFs offer minimal short fiber content and neps and a stable, consistent fiber length. When blended with recycled cotton, they can increase the average fiber length of the mix and reduce the share of short fibers, improving spinnability and reinforcing yarn formation on ring spinning systems. This means the mis remains 100% cellulosic, as the original mix is.

A comprehensive trial was conducted with three partners:

• Recover supplied 100% cotton post-industrial waste fibers for the recycled component.

• Birla Cellulose supplied multiple variants of Excel™ (lyocell) fibers with different length and fineness.

• Rieter provided the spinning and evaluation expertise and compiled results in a dedicated technology report.

The study benchmarked a typical reference blend (80% virgin cotton + 20% recycled cotton) against new blends where virgin cotton was replaced by different MMCF options, and the recycled cotton share was increased (including trials at 20%, 40% or 60% recycled content!). The target was to identify fiber specifications that maximize recycled content without compromising yarn and fabric quality.

Key results: higher recycled content, improved performance

The standout finding reported by Rieter: using cellulosic fibers in place of virgin cotton made it possible to spin yarns with 40% recycled cotton (double the share commonly used in practice!) while achieving strong quality outcomes. In the report summary, Rieter notes that a blend of 40% recycled cotton + 60% Birla Excel (lyocell) delivered significantly better yarn evenness, more even fabric appearance, better hairiness behavior and better pilling behavior.

In other words, increasing recycled content did not require a trade-off. Under the right fiber selection, the “higher recycled” blend performed as well as (or even better than!) the conventional reference.

From an innovation perspective, this detail is crucial. Many sustainability improvements stall when they introduce new complexity downstream. Here, the approach intentionally keeps the yarn composition within one family of materials, cellulosics, helping preserve a familiar cotton-like look and feel, compatibility with existing textile processing routes and potential for recyclability in future circular systems.

For mills and brands, that means recycled content can grow in a way that supports both product quality and circular design intent. Concretely, this means:

• • A pathway to higher recycled cotton in ring yarns

If recycled content can move from 20% to 40% without compromising performance, that unlocks new commercial possibilities across categories that require stable quality.

• Maintaining a fully cellulosic composition

Cellulosic fibers are widely used for their specific characteristics, including comfort, moisture absorption, and warmth, with cotton remaining the most commonly used natural fiber for these applications. Substituting virgin cotton with man‑made cellulosic fibers (MMCFs) preserves the functional properties of the original fibers while enabling further mechanical recycling of the resulting blend, which remains 100% cellulosic.

• A clearer “blend strategy” for mechanically recycled fibers

Rather than treating recycled cotton’s short fiber content as a fixed barrier, the trial demonstrates a method to manage it through complementary, consistent-length cellulosic fibers.

• Innovation that fits industrial reality
  The outcome is not a lab-only concept; it is built around real spinning constraints and measured fabric outcomes, which are decisive for product adoption.

Innovation as a commitment

Recover’s approach to circularity has always been grounded in scale and real-world application: building solutions that help the industry increase recycled content in textiles without sacrificing quality or longevity.

This collaboration reinforces that commitment. By combining Recover’s mechanically recycled cotton expertise with Rieter’s spinning know-how and the complementary properties of man-made cellulosic fibers, the trial demonstrates a tangible route to more circular, higher-recycled yarns, all made for the demands of modern textile production. As the industry continues to push for measurable progress -driven by customer expectations and regulatory direction- Recover will keep investing in innovation partnerships that turn the toughest technical barriers into scalable outcomes.