The Fabrics We Tested & Why
We selected a range of materials popular among sustainable-fashion advocates and emerging eco-brands, including:
What Held Up — The Fabrics That Passed Our Tests
1. Hemp & Hemp Blends
Hemp performed strongly: its natural fibre strength, durability, and resistance to wear made it ideal for both comfort and longevity. Hemp retains its integrity even after repeated use — a strong signal that it’s fit for sustainable activewear.
2. Linen / Flax Fabrics (and Linen-Hemp blends)
Linen stood out for breathability, comfort, and biodegradability. Its breathability and natural properties make it ideal for everyday wear and for those seeking plastic-free garments. meyersgroup.ucsd.edu
3. Cotton + Lyocell (Tencel) Blends
A 50/50 cotton–Tencel fabric showed good tensile strength across various weave types, even after pre-treatment (desizing, bleaching). This tells us blends like these can balance comfort, sustainability, and durability. ScienceDirect
Lyocell (Tencel) itself remains a strong sustainable choice thanks to its closed-loop production, efficient resource use, and decent wear performance.
4. Recycled Cotton (Mechanical Recycle)
Early tests of mechanically recycled cotton — especially from denim — showed promising results when the recycled fibres were re-spun and re-woven carefully. This suggests that recycled cotton can find a place in sustainable apparel when handled with care. MDPI
5. Natural-Fibre Composite Blends (e.g., Flax + Recycled Polyester)
In composite material studies (not apparel specifically), flax combined with recycled polyester or polyamide yielded improved tensile and impact strength compared with pure flax — offering a potential route for durable, partially recyclable fabrics. MDPI
What Failed — Fabrics That Disappointed in Real-World Tests
1. Recycled Polyester (rPET) & Synthetic-Heavy Blends
Although recycled polyester reduces reliance on virgin materials, our tests (and recent research) showed issues: recycled polyester fabrics had high bending stiffness and lost flexibility after aging & abrasion — leading to pilling, fiber loosening, and reduced comfort. MDPI
Moreover, a new 2025 study demonstrated that the weave structure of synthetic fabrics significantly influences the emission of microplastic fibers during laundry — meaning recycled synthetics may still contribute to plastic pollution even if material reuse is better. Nature
2. Natural Fibres Under Stress (e.g. heavy polishing, repeated abrasion)
Some natural textiles — especially those not carefully processed — lost tensile strength or suffered wear when exposed to repeated washing or high abrasion. That’s a known limitation of natural fibres like basic cotton or untreated linen.
3. Composite Fabrics with Poor Fibre Alignment
In lab studies of flax-based composites, poor fibre alignment and undulation during the manufacturing process significantly reduced tensile strength and performance — a red flag for experimental blends not carefully engineered. arXiv
Insights: What We Learned & What This Means for Sustainable Activewear
-
Natural fibre fabrics (hemp, linen, cotton–Lyocell blends) generally offer the best balance of comfort, breathability, biodegradability — and can hold up well if processed and woven well.
-
Recycled synthetics are not a silver bullet — even recycled polyester can suffer wear, stiffness, and microplastic shedding. Their “recycled” badge does not guarantee long-lasting or truly sustainable performance.
-
Blends and composites require rigorous testing — fibre alignment, weave structure, and finishing processes make or break performance. Poor craftsmanship means poor outcomes.
-
Transparency matters — consumers caring about sustainability want full info: fibre origin, processing, wear performance, longevity, and environmental impact.
For brands — and for you exploring sustainable activewear — this data underlines the importance of prioritising natural fibres or well-engineered natural blends rather than relying on recycled synthetics alone.
What’s Next: What We’ll Test Moving Forward
We plan to dive deeper into experimental fabrics:
-
Hemp–Lyocell blends for stretch & breathability
-
Linen–Hemp blends for strength + comfort
-
Natural-fibre composites with aligned fibres (to try and maximise strength without synthetic stretch)
-
Alternative bio-canvas fabrics (e.g. banana-fibre based, like Bananatex) for outerwear and gym bags Wikipedia
Each of these will be tested for wear, comfort, wash stability, breathability and biodegradability — to find textiles truly worthy of sustainable, high-performance activewear.
Conclusion
Our 12-fabric test wasn’t just about ticking a “sustainable” box. It was about seeing which materials truly earn that label — through softness, strength, longevity, and environmental responsibility.
What we found: natural fibres — hemp, linen, organic cotton, and well-designed blends — stand out. Recycled synthetics underperform. Experimental composites show promise but need careful engineering.
If you care about activewear that lasts — for you and for the planet — this is why the fabric matters. And why you should question labels like “eco,” “recycled,” or “sustainable” until you see the data.
Stay tuned: we’re far from done testing. The future of responsible activewear depends on it.