How to read a mill's sustainability data pack: what to verify
Certificates, chemical management and facility data each prove something different. What to check, and what each document does not show.
KEY TAKEAWAYS Summary by the editors
- A mill's data pack usually mixes product certificates, chemical management evidence and facility performance data, and each answers a different question.
- OEKO-TEX Standard 100 tests textiles for harmful substances, certificates are issued for one year, and they can be verified by QR code or certificate number on the OEKO-TEX website.
- Higg FEM (Facility Environmental Module) gives insight into a manufacturing facility's environmental performance, such as water use and carbon emissions, and verification makes the data more consistent and comparable.
- The ZDHC Manufacturing Restricted Substances List (MRSL) is a unified list of chemicals to phase out of supply chains, which relates to input chemistry rather than to the finished product.
- Always check scope, validity dates and whether a document covers the specific facility, product and period you are buying, not just the company name.
To read a mill's sustainability data pack, sort each document by what it proves (product safety, chemical management, facility performance or material origin), then check scope, dates and verification for each. A certificate shows that a specific scope was assessed at a specific time, not that the whole company is sustainable. The notes below cover common documents and the questions they should prompt.
What does each document prove?
| Document | What it covers | What to check |
|---|---|---|
| OEKO-TEX Standard 100 | Textiles tested for harmful substances, in four product classes | Certificate number, class, validity (issued for one year), verification via QR or the label check |
| Higg FEM | Facility environmental performance, such as water and carbon | Whether the data is verified, which year, which facility |
| ZDHC MRSL conformance | Restricted chemicals in manufacturing inputs | Which chemical suppliers and formulations are covered |
| bluesign | Chemical safety and environmental impact, via system partners | Whether the product, mill or only a supplier is covered |
| Textile Exchange standards | Content and claim standards such as organic, recycled, down and wool | Chain of custody and certificate scope |
What do OEKO-TEX certificates tell you?
OEKO-TEX describes Standard 100 as a label for textiles tested for harmful substances from yarn to finished product, with every thread, button and accessory tested against a list of over 1,000 substances. Testing depends on intended use, sorted into four product classes from baby products (the strictest) to home textiles. Certificates are issued for one year, and can be checked by scanning the QR code on the label or entering the certificate number in the OEKO-TEX label check. Verify the certificate yourself rather than relying on a copy in the pack, and match the article and product class to what you are buying.
What does Higg FEM show, and what does it not?
Cascale describes the Higg FEM as a tool that gives insight into a manufacturing facility's environmental performance, covering topics such as water use and carbon emissions. Its verification programme aims to make Higg data more consistent, comparable and credible and to reduce the need for multiple proprietary audits. Ask for the verified score and the reporting year, and check that the facility named is the one that will make your product. A facility assessment says little about the fibre, farm or dye house upstream.
How do chemical management documents fit in?
The ZDHC Foundation, which stands for Zero Discharge of Hazardous Chemicals, publishes a Manufacturing Restricted Substances List, a unified list of harmful chemicals to phase out of supply chains. Ask the mill which chemical inputs it uses, whether suppliers are conformant, and how it verifies this. bluesign describes itself as a certification and sustainability services company working with brands, manufacturers and chemical suppliers, and lists over 900 system partners in more than 50 countries on its site. Check whether the partner status applies to the mill or to a supplier, since the claim differs.
What material claims need chain-of-custody checks?
Textile Exchange manages standards such as the Organic Content Standard, the Recycled Claim Standard, the Global Recycled Standard, and standards for down, wool, mohair and alpaca. Claims such as organic or recycled content are only as good as the chain of custody behind them, so ask for the transaction certificates that link the purchase to a certified input, not only the mill's own certificate.
What is a practical review routine?
- List every document and write one line on what it proves.
- Check validity dates and the legal entity and site named.
- Verify certificates with the issuer, using the number or QR code.
- Compare data across documents for contradictions.
- Record gaps and ask for specific evidence, rather than general assurances.
- Store the pack in a structured form, with dates, so changes can be tracked.
Remember also that regulation is moving. The Ecodesign for Sustainable Products Regulation is in force and digital product passports will require structured information for product groups as the Commission defines them. Documents that are only PDFs today may need to become data tomorrow, so ask whether the mill can provide the key fields in a structured form, with certificate numbers, dates and scopes, rather than only scanned files.
Finally, keep the review proportionate. A basic cotton fabric from a long-standing partner may need a light check, while a new mill supplying a claim-heavy product needs deeper review. Risk, claim strength and volume should set the effort.
A fair expectation is that a mill's pack will not be complete. Smaller mills often hold some certificates but not others, and a missing document is not proof of poor practice. It should, however, lead to a specific question and a date by which the answer is expected.
What questions should you ask the mill directly?
- Which products, sites and periods does each certificate cover?
- Who verifies the data, and when was it last verified?
- Which chemical suppliers do you use, and are they conformant with industry lists?
- What do you know about the origin of your fibre and yarn?
- How do you handle subcontracting, such as dyeing or finishing at another site?
- Who is the contact for questions, and how quickly can you respond?
Subcontracting deserves particular attention. A pack may describe the main mill while a stage such as dyeing is done elsewhere, which means the pack does not describe the process that produced your fabric. Ask for the same evidence for every site involved, or an explicit statement of which stages are covered. Keep the answers with the pack so that a future audit or customer query can be answered without starting again.
Finally, be wary of unsourced percentages or comparisons in the pack. A statement such as a percentage saving in water or emissions should state the baseline, the period and who verified it. If it does not, treat it as a marketing statement, not a data point.
Frequently asked questions
How can I verify an OEKO-TEX certificate?
OEKO-TEX says to scan the QR code on the label or enter the certificate number in its label check on the website. Certificates are issued for one year, so check the date.
What is Higg FEM?
The Facility Environmental Module is a Higg Index tool, described by Cascale as providing insight into a facility's environmental performance, including water use and carbon emissions.
Does a certificate mean the whole mill is sustainable?
No. A certificate covers a defined scope, product or facility at a point in time. Always check what is included and the dates.
What is the ZDHC MRSL?
It is the ZDHC Manufacturing Restricted Substances List, a unified list of harmful chemicals that industry aims to phase out of supply chains.
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