CircStretch™ Knits

CircStretch™ eco-stretch textile range is a unique blend of premium stretch fibres and dyes that carry the highest trusted industry benchmark Certifications for each of the 7 impacts: 

1. bulk textile:
   Lenzing's TENCEL™ renewable plant-based fibres hold the industries leading eco-Certifications; from forests to yarn. 100% biodegradable.

2. biodegradability:
   certified testing to achieve highest biodegradability and low toxicity (eg addressing microplastic mitigation from wash and wear, plus activate Circular Business Model to divert from landfill)

3. elastane:
   To add the 4-way stretch and recovery for durability, we use the world’s highest-certified eco-elastane ROICA™ V550 degradable elastane fibre holds Cradle 2 Cradle Gold standard. It is 50% biodegradable and is the least harmful elastane available. 

4. dyes and testing:
   highest certified low-tox dyes plus multi-stage testing from fibre to finished textiles including full-system upstream process certification from bluesign® - combined with OEKO-TEX® Standard 100 for final textile certification.

5. factory audits and certification:
   each factory is audited to hold international Standards and Certifications including bluesign® systems to enhance environmental impact mitigation and uphold Standards that monitor for continuous improvement.  

6. circularity: divert products from landfill to circular pathways (eg meet EU's Extended Producer Responsibility regulations) - STSC offers RFID Digital Product Passports (DPPs) for B2B circularity, with traceable data for brands to connect with circular pathways (Extended Producer Responsibility first before recycling).

7. verifiable data: STSC offers traceable data to add to DPPs and QR Code PRODUCT IDs for B2C that follows the United Nations Transparency Protocol (UNTP) to facilitate global data interoperability and support brands to meet regulatory requirements (eg. EU's EcoDesign for Sustainable Product Regulations, Green Claims Directive, Waste Framework Directive, etc). 

Our data meets the EU regulations aimed at stopping "vague environmental claims, generic sustainability claims, whole-product claims based on only one component, and claims lacking verification or evidence".

Note: eg. no brand can legally claim their 4-way stretch knits are "100% biodegradable", or "100% plastic-free" as elastane is derived from non-biodegradable fossil fuel source). Or "100% non-toxic or toxic free" - textile supply chains involve chemicals somewhere, eg the finished textile may be tested for harmful residues, but that is different from proving the entire product is "non-toxic". 

Legal advisors require evidence-based claims including : "certified to OEKO-TEX® Standard 100", "manufactured using bluesign® approved chemistry".

The Problem With Conventional Activewear

Most activewear is made from 80–95% polyester or nylon (Polyamide) - plus, in all cases, stretch textiles are blended with 5–20% elastane (Spandex, Lycra). All are derived from a fossil-fuel source - recycled nylon, recycled polyester and recycled elastane are still plastics that are non-biodegradable and shed untold microfibres into soil, waterways, food systems and human bodies throughout each lifetime.

Recycling synthetics may improve circularity compared with virgin petrochemicals, but they do not eliminate synthetic polymers from the textile system or its impact. 

Anti-greenwashing should prohibit brands from referring to these recycled products as 'eco-sustainable', 'plastic-free' or even 'non-toxic'. Additionally, technically no textile is 'non-toxic' simply because chemicals are used in all processes - from farming cotton, bamboo and hemp to the closed-loop systems of Lenzing using chemicals to breakdown the wood fibres.

This is why verifiable Certification is key to offering trusted products that actively minimise the impact.

• All uncertified textiles such as cotton, bamboo, generic lyocell or modal and recycled bottles (rPET) or standard recycled textiles derived from fossil fuel synthetic fibres do not meet STSC's high standards for certified sustainability. 

• For our plant fibres, STSC chose Lenzing yarn instead of GOTS (Global Organic Textile Standard) certified cotton for several reasons including Lenzing holds the highest Certified industry standards at each stage, from forest to finished yarn alongside a premium, tested durability.

• Lenzing fibres hold responsible wood sourcing certified to FSC® (Forestry Stewardship Council) and PEFC standards, highest CanopyPlanet audits, closed-loop production systems designed to recover and reuse process chemicals, wastewater treatment protections, medically tested for toxins and independent certifications for harmful substance testing including bluesign® and TÜV Austria certifications for biodegradability and compostability.  

• Lenzing's manufacturing data shows that TENCEL™ Lyocell fibers are produced using a closed-loop process that recovers more than 99% of the solvent and process water used during production. The system is designed to capture, recycle, and reuse the solvent internally, significantly reducing chemical discharge and freshwater impact compared with conventional viscose production.

• We prefer Lenzing's system rather than GOTS organic cotton as GOTS does not inherently involve a closed-loop regenerated cellulose solvent recovery system like Lenzing.

• GOTS certification is primarily focused on the raw fibre source only (cotton farming). Lenzing’s systems incorporate independently certified environmental standards across the broader manufacturing process — including responsible wood sourcing (FSC®/PEFC), closed-loop solvent recovery systems, wastewater treatment, chemical management, worker protections, biodegradability certifications, and harmful substance testing. 

• While certifications such as GOTS provide strong standards for organic cotton cultivation and processing, TENCEL™ fibers are differentiated by their integrated closed-loop fibre production technology and solvent recovery systems designed to minimise environmental impact throughout the entire manufacturing process - from forest to the yarn.
  
  

• FULL SYSTEMS CERTIFICATION
  All textiles shed fibres into our environment - therefore textiles with any synthetic fibres will hold and shed microfibres made from plastic. In addition, new research shows further concerns regarding fibres containing hazardous chemical dyes and finishes, especially when combined with synthetic fibres.  Check the certifications as they may hold undocumented hazardous chemical dyes and finishes.

• Many brands do not declare all details - and this combination has the potential to cause increased negative health impacts, especially from garments worn close to the skin when we exercise, plus environmental impacts if waste water is not captured and treated and from microfibre pollution plus when ingested from water, soil, food systems and air.

• Even with plant-based natural fibres, all 4-way stretch textiles still contains some plastic elastane knitted in, therefore we're still wearing some plastic and shedding some microplastics - CircStretch™ is designed to minimise the non-biodegradable synthetic content to the lowest possible percentage for textiles currently on the market.
  
  

• CIRCULAR BUSINESS MODELS
  STSC aim to divert products made with CircStretch™ from any landfill, and work with the Global Circular Network to support brands to activate take-back programs for Extended Producer Responsibility (EPR) before diverting to recyclers who identify the eco-status and offer as verified next-gen feedstock for trusted Certification (fibre to fibre or remanufacturing).

• Bulk yarn: Plant-based fibres: Lenzing TENCEL™ Lyocell & Modal

The primary fibres in CircStretch™ are Lenzing TENCEL™ Lyocell and Modal - Lenzing manufacture regenerated cellulose fibres produced from certified wood pulp (eucalyptus, beech, pine) in a closed-loop manufacturing process where over 99% of the solvent is recovered and reused. 

When we look at the microfibres, these biodegrade in real-world environments in around 30 to 63 days - see testing in Biodegradability of Microfibres. STSC's aim is to facilitate circular pathways that support brands and customers to divert CircStretch™ to sorters for identification then to fibre to fibre recyclers so they are not left to decompose in dry unaerated landfill. Tested polyester remained unchanged after 200+ days. Estimated degradation time for synthetic fibres: over 200 years.

This means the microfibres shed by CircStretch™ fabrics during washing and wear are primarily plant-derived and biodegradable plus are not compromised with hazardous chemicals or persistent plastic.

• CircStretch™ developed with the minimum possible non-biodegradable stretch content - Roica V550

All stretch textiles require elastane for 4-way stretch. Conventional elastane is 100% non-degradable and estimated to persist for 200+ years. There is no commercially available fully biodegradable elastane. What differs is how harmful the elastane is - plus how much of it degrades when it does break down related to microfibres. 

CircStretch™ uses ROICA™ V550 by Asahi Kasei: ROICA™ V550 is the world's first elastane certified Cradle to Cradle Certified™, awarded Material Health Gold certification. No other elastane on the market currently matches this certification profile. 

It is the only elastane that partially degrades under biologically active conditions (ISO 14855-1, tested by OWS), breaking down into CO₂ and water without releasing harmful substances. Published data: approximately 35% degradation within 270 days; approximately 50% within 24 months.

All conventional elastane (Spandex, Lycra, recycled elastane) shows essentially zero degradation under the same conditions and is estimated to persist for over 200 years, releasing plastic microfibres throughout. 

ROICA™ V550 also holds OEKO-TEX® Standard 100 Class 1 certification at yarn level — independently verified free from harmful substances.

STSC's CircStretch™ range with ROICA™ V550 elastane has a tiny component of non-biodegradable synthetic elastane fibres (50% or half of the elastane component)- but much less than 100% conventional elastane alongside the bulk textile.

ROICA™ V550 is a polyurethane-based elastane — the same polymer family as conventional Spandex/Lycra. It is not bio-based in its raw material origin. It is still derived from fossil fuel chemistry (polyurethane is made from petrochemical precursors). What makes it different is:

• It is engineered to partially degrade (unlike conventional elastane which doesn't degrade at all), breaking down into CO₂ and water without releasing harmful substances

• It holds the highest sustainability certifications available for any elastane — Cradle to Cradle Gold Material Health + OEKO-TEX® Class 1 

• It is the least harmful elastane available — not plastic-free, but the closest thing to it that currently exists on the market today.

FULL-SYSTEMS CERTIFICATION 

Many stretch textiles on the market may achieve product-level testing such as OEKO-TEX® Standard 100, however comparatively few are manufactured within bluesign® approved facilities operating under the bluesign® system. Unlike standards that focus solely on the finished fabric, bluesign® evaluates the entire production ecosystem, including chemical inputs, dyeing processes, environmental emissions, water and energy consumption, worker safety and ongoing compliance management. 

This systems-based approach provides a higher level of confidence that sustainability, chemical safety and environmental performance have been embedded throughout production rather than verified only at the final testing stage. When paired with OEKO-TEX® Standard 100 testing of the finished textile, it represents one of the most robust combinations of process and product assurance currently available within the global textile industry. 

• bluesign® CERTIFIED CHEMICAL SYSTEMS - UPSTREAM PLUS DYES

bluesign® certifies chemical inputs before they enter production, eliminating harmful substances at the source rather than testing for residues after the fact. CircStretch™ mills are bluesign® System Partners, which requires the use of bluesign-approved chemistry including all dyes and auxiliaries. 

Lenzing also holds bluesign® System Partner certification at fibre level. bluesign®-approved chemistry therefore runs from fibre production through dyeing and finishing.

• OEKO-TEX® STANDARD 100 CLASS 1 AT EVERY STAGE

OEKO-TEX® Standard 100 Class 1 — covering garments worn directly against skin — is independently verified at three levels: 

1. the TENCEL™ Lyocell yarn

2. the ROICA™ V550 elastane yarn 

3. and the finished textile. Independent testing at all component stages is rare in the market.

• CERTIFIED MANUFACTURING

Alongside the bluesign® system in place for STSC's partner factory - CircStretch™ is produced in a Better Work (ILO–IFC) certified mill with ISO 14001 Environmental Management, integrated heat recovery systems for steam and wastewater, and full REACH compliance including the ECHA SVHC candidate list.

• ANTI-GREENWASHING AND VERIFIED CERTIFICATION

STSC follows the strict anti-greenwashing guidelines created by the EU Commission as part of the EU Circular Economy Action Plan and assist brands to meet regulations including the EU's Ecodesign for Sustainable Products Regulation (ESPR) in force from July 2024. 

All traceable Certifications will be issued when purchasing textiles.