The Global Recycled Standard is the second of the two big sustainability certifications most apparel brands reference today, and the one most often misunderstood. GRS is not a "recycled content" claim that is self-declared by a yarn supplier: it is a full chain-of-custody certification with social criteria, chemical criteria and a TC-based documentation model — structurally similar to GOTS but with recycled fiber instead of organic. This guide walks through the four feedstocks we use to make GRS socks, the five operational steps from waste to finished product, and the documentation every buyer should ask for.
What GRS Actually Certifies
Originally launched by Textile Exchange in 2008 and significantly revised in 2017, GRS tracks recycled material through every step from the source (collector, sorting facility) to the finished product. It does not certify the recycling process technology itself — that would be a separate claim under ISO 14021 or the EU Ecolabel — but it does certify that the recycled input was properly tracked, that processing met chemical and social criteria, and that the finished product contains at least 20 percent recycled material by weight.
The four pillars of GRS are: recycled content verification, chain of custody, social criteria, and environmental (chemical and wastewater) criteria. The last two are inherited almost verbatim from GOTS, which is why mills holding both schemes typically share documentation and audits.
The Four Feedstocks FOCS Uses in Sock Programs
Not every recycled yarn works for socks. Performance demands are high — socks need abrasion resistance, elasticity recovery and foot-shaped fit — so the recycled feedstocks have to be regenerated into a quality fiber rather than mechanically shredded. The four we work with regularly are:
- Regenerated nylon (Econyl, equivalent). Post-consumer fishing nets and industrial nylon waste depolymerised and re-polymerised into virgin-grade nylon 6 chip. The most common recycled sock component. Performance matches fossil-derived nylon.
- Recycled polyester (rPET). Post-consumer PET bottles and pre-consumer polyester waste re-melted and re-extruded into filament. Often used in technical socks and dress socks with moisture-wicking claims.
- Recycled cotton. Mostly pre-consumer cutting waste from cutting rooms. Fiber length is short, so recycled cotton typically pairs with virgin cotton or modal to meet spinning requirements. Useful for home and casual sock programs.
- Recycled wool. Pre-consumer wool waste from spinning and knitting mills, shredded and re-spun. Coarser count, used primarily in heavy boot and hiking socks.
From Waste to Finished Sock: Five Operational Steps
The operational pathway for a GRS regenerated nylon sock sold in Copenhagen:
- Collection. Discarded fishing nets are collected from Mediterranean and Asian fisheries by the regeneration partner. Each lot is weighed, tagged with a unique code, and assigned a "scrap" TC by the collection partner's GRS scope.
- Regeneration. The nets are cleaned, depolymerised and re-polymerised into virgin-quality nylon 6 chip. This step is energy-intensive and the largest carbon contributor in the chain. The regeneration facility holds a GRS scope covering the entire depolymerisation-to-chip process.
- Spinning. The chip is melted and extruded into filament yarn, typically DTY (draw-textured yarn) for sock knitting. The spinning mill holds a GRS scope and issues a TC for each yarn lot.
- Knitting and assembly. FOCS knits, dyes, sews and packs the sock under its own GRS scope (TE-00060119). All dyes and chemicals are GRS-compliant; the dye-house is GRS-certified or sub-contracted under FOCS' scope.
- Shipment and documentation. FOCS issues a shipment-specific TC tied to the buyer's PO. The TC is the buyer's authority to mark the finished product as GRS at retail.
Each step in this chain is audited annually, and the input-output mass balance is reconciled across scopes. A 100 percent GRS scope means the mill only handles recycled fiber; a mixed scope means the mill handles both recycled and conventional fiber under documented time-segregation rules.
The Chemistry Restrictions Matter
GRS inherits most of its chemical restrictions from GOTS, with a few differences. Specifically, GRS allows a slightly broader list of dye auxiliaries, including some surfactants and carriers that GOTS would reject. For brands with strict chemical policies, FOCS recommends specifying a tighter RSL — e.g., the ZDHC MRSL or a retailer-specific list — on top of GRS to be doubly safe. In practice, FOCS' default GRS dye-house list exceeds ZDHC Level 1, which is the practical benchmark for European and North American retail compliance.
The most common chemical-issue scenario with recycled nylon is residual solvents in the depolymerisation step. Good regeneration facilities run strict QA on the chip before it ships, but FOCS recommends a quarterly third-party chemical snapshot for any GRS program above 50,000 pairs per shipment. This is a small cost and worth the insurance against a retailer recall.
How FOCS Documents Each Shipment
For a confirmed GRS order, the buyer's documentation pack from FOCS includes the mill's GRS scope, the yarn TC, the dye-house TC, the shipment TC, a chemical-input declaration, and (on request) a mass-balance reconciliation showing the recycled content verified for the buyer's specific lot. We deliver this by email the day before the goods leave our loading dock, so the buyer's compliance team has time to file the TC and update the retailer's listing.
For first-time buyers evaluating GRS as a category, we run a sample test program before formal PO: 200 to 500 pairs of recycled nylon socks, with full documentation, so the brand can verify the supply chain in their own name before committing to a season program.
Common Buyer Errors with GRS
- Self-claim with no scope verification. "Recycled yarn" in a supplier's marketing may not be GRS-certified. Always check the supplier's scope on Textile Exchange's public database.
- Recycled-content miscount. The buyer should compute the recycled percentage on weight, not unit count. A 50-pair pack of recycled-nylon socks may only contain 30 percent recycled material by weight if the elastic and cotton are virgin.
- Missing sub-contractor list. If the dye-house or printer is not in the supplier's GRS scope, the chain is broken. FOCS provides a sub-contractor list with the TC pack on request.
- GRS versus GOTS confusion. Recycled cotton does not equal organic cotton. The two schemes track different claims and use different positive-list chemicals. A sock can carry both certifications if the recipe supports it.
GRS, GOTS, OCS and How They Stack
A blended-fiber sock — for example, 70 percent GOTS Organic Cotton, 25 percent GRS Recycled Nylon, 5 percent elastane — can carry both certifications, with two separate TC chains and a single composite labeling guideline. FOCS routinely runs blended programs and consolidates the documentation into one TC pack with twin codes. This is the most efficient way to meet a brand's "organic" and "recycled" category claims simultaneously without doubling the per-pair cost.
The other scheme in the same family is OCS (Organic Content Standard), which tracks organic content through processing but with lighter environmental and social criteria. OCS is appropriate where GOTS-level processing standards are not required — e.g., where the input is recycled-organic blend textile. FOCS is certified to all three.
Frequently Asked Questions
What is the minimum recycled content to be GRS certified?
GRS requires at least 20 percent recycled material in a finished product to carry the GRS label. Products with 50 percent or more recycled content can be marketed with a higher claim. FOCS' GRS sock programs typically run between 30 and 95 percent recycled content depending on the chosen feedstock and blend.
Are pre-consumer and post-consumer waste treated the same way?
No, the scope differs significantly. GRS accepts both pre-consumer waste (factory offcuts, yarn waste, fabric overruns) and post-consumer waste (used fishing nets, PET bottles, discarded garments). The chain-of-custody documentation is more rigorous for post-consumer streams because the collection and aggregation steps require additional verification.
Can recycled nylon from fishing nets be used in socks safely?
Yes, when processed through a GRS-certified regeneration facility. FOCS uses Econyl and similar regenerated nylon yarns for sock programs. The feedstock is typically discarded fishing nets collected from Mediterranean and Indian Ocean fisheries, cleaned, depolymerised and re-polymerised into a virgin-quality nylon 6 chip. The finished yarn carries the same performance as fossil-based nylon 6.
Does GRS cover social compliance too?
Yes. While GRS is best known for recycled content, it includes a full social section built on the same ILO conventions used by GOTS. The 2017 standard revision made social criteria mandatory at all levels: workers' rights, health and safety, and minimum wage compliance are audited alongside the chain of custody. Some certification bodies, including Control Union, run GRS and GOTS audits in a single combined visit for mills holding both.
What is a TC (Transaction Certificate) in GRS?
Same principle as GOTS: a TC is the document that ties a specific shipment back to the seller's GRS scope. Without a TC for each shipment, the goods cannot legally be marketed as GRS. FOCS issues a TC automatically with every shipment, no separate request needed.
Can I use recycled cotton in socks?
Recycled cotton is technically possible but commercially difficult for socks because the fiber length shortens dramatically during recycling, limiting spinning to coarse counts. Most FOCS blends use recycled nylon or recycled polyester paired with virgin cotton, GOTS-certified cotton, or bamboo. Pure recycled cotton programs typically suit weaves more than knits.
Does GRS cover the chemical inputs in dyeing recycled fiber?
Yes. GRS has a chemical restriction list similar to GOTS but slightly more lenient on certain dye auxiliaries. The dye-house must be in scope, must declare all chemical inputs, and must demonstrate wastewater treatment. For blended programs with both GOTS Organic and GRS Recycled fibers, FOCS uses a single dye-house that holds both scopes to keep the documentation chain clean.
Continue Reading
- FOCS Recycled Nylon Faux Mink Socks (regenerated nylon program)
- GRS Recycled Fishing Net Swimwear — same feedstock, different garment
- Recycled Socks Manufacturing: 5 Materials Buyers Can Actually Use
- GOTS Certification Process Explained
- Sustainable Socks Manufacturer — overview page