How do I prove a TENCEL Modal or Lyocell claim on my underwear?

Short answer: TENCEL is a Lenzing trademark. Using it requires fibre sourced from Lenzing and compliance with Lenzing's branding and licensing rules, typically with documentation through the supply chain. The fibre content label still uses the generic fibre name, such as modal or lyocell.

What is needed

• Documentation from the fibre and yarn supply chain showing Lenzing fibre.
• Approval to use branding according to Lenzing's guidelines.
• A correct fibre content label in each market.

Steps

• Ask the mill early whether it can supply branded fibre with documentation.
• Apply for branding approval if required.
• Keep certificates and purchase records for each order.

Limits

Branding approval does not replace legal fibre labelling. Check that marketing claims about softness or sustainability are accurate and supported.

What retailers typically ask for

Retailers vary, but common requests include a document from the fabric supplier identifying the branded fibre, proof of branding approval for the packaging artwork, and the fibre content test or declaration that matches the label. Some also ask for chemical compliance documents for the finished product. Collecting these during development avoids delays at onboarding.

Branding versus fibre labelling

Two separate things are often confused. The fibre content label is a legal requirement and must use generic names such as "modal" or "lyocell" with percentages. Trademark branding such as "TENCEL" is optional marketing that follows the trademark owner's rules. A garment can be legally labelled "95% modal" without any branding; it cannot use the brand name without approved sourcing. Keeping these two layers distinct avoids both compliance and trademark problems.

Blends and percentages

If branded fibre is only part of a blend, the branding guidelines may set conditions on how it is described. Check these before artwork is finalised so that hang tags, packaging and online listings stay consistent with the label and with the approval you received.

How Lenzing's programme works in practice

Lenzing licenses its TENCEL brand for use on products that contain its fibres and that meet its labelling and minimum-content rules. Brands typically register with Lenzing's licensing service, submit artwork for approval, and need traceable documentation showing that the fibre in their fabric came from Lenzing, often through a fibre identification or certification process along the supply chain. Requirements and procedures are set by Lenzing and can change, so the current brand guidelines should be checked for each new programme.

A practical claim file

• Fibre supplier documentation linking your fabric to Lenzing fibre.
• Fabric and garment composition on lab reports.
• Approved artwork for labels, hang tags and online use.
• Correct generic fibre names on the composition label, such as modal or lyocell.

This file is what retailers and auditors usually ask for.

Facts, recommendations and uncertainty

Established: TENCEL is a trademark with branding rules. Recommendation: secure documentation before printing branding. Uncertain: specific retailer requirements, which vary.

Sources and further reading

• Lenzing — TENCEL™ Modal with Micro technology
• U.S. FTC — Textile Fiber Products Identification Act
• Regulation (EU) No 1007/2011 — Textile fibre names and labelling

Standards and regulations are referenced by their published scope. Test parameters, cycles and pass levels should be agreed with your laboratory for the specific product; legal requirements should be confirmed for each destination market.