https://www.avient.com/news/new-technology-avient-helps-trace-origin-fibers-polyester-and-polyamide-textiles
This can be an issue in cases of claims, but also when labeling textiles for special features like ‘recycled content’ or the certificate of origin (e.g., ‘made in …’).
In the case of recycled grades, fiber manufacturers can use the tracer concentrate pellets earlier in the production process by adding them to the recycled polymer content (e.g., polyethylene terephthalate bottle flakes or shredded nylon fishing nets) prior to being extruded into pellets.