For the US market, the FTC's Green Guides set out how environmental claims are treated, and 16 CFR 260.13 covers recycled content claims. The section says claims of recycled content should be made only for materials recovered or otherwise diverted from the waste stream, during manufacturing (pre-consumer) or after consumer use (post-consumer). If the recycled content includes pre-consumer material, the marketer should have substantiation that it would otherwise have entered the waste stream. Your evidence therefore needs to show what the recycled material is and where it came from.

Ask for documentation, not a description

Ask the mill for documentation that traces the recycled content from its source through the yarn to your fabric lot. Ask for the percentage of recycled content in the fabric, whether it is pre-consumer, post-consumer or both, and how that is verified. Many mills use third-party chain-of-custody certification for this. If they do, ask for the certificate and the transaction documents for your order, not only a general certificate for the mill.

Be specific about how much

The Green Guides address qualifying claims when a product is only partly made from recycled material. If the leggings fabric is a blend, or only one component is recycled, the claim should make the proportion clear, for example a stated percentage of recycled polyester in the main fabric. An unqualified "made with recycled materials" may imply more than the evidence supports. Section 260.13 also says a marketer that distinguishes pre-consumer from post-consumer content should be able to substantiate the percentages.

Keep the fibre label separate

The sewn-in fibre content label follows the Textile Act rules in 16 CFR Part 303 and uses generic fibre names and percentages. Marketing claims about recycled content are separate, so keep the fibre label accurate and make the recycled claim on the hangtag or product page with its own substantiation.

Keep the evidence current

Recycled content can change between fabric lots. Make the documentation part of each bulk delivery, and update the claim if the content changes.

Other markets have their own rules on environmental claims, so if you sell outside the US, check those too before using the same copy. The documentation you collect for the US claim is usually the starting point everywhere.