What are azo dyes and why are some restricted?
Azo dyes are a large family of dyes, widely used because they give bright shades at a low cost. Most are fine. A small number can break down, for example in contact with sweat on the skin, and release aromatic amines, some of which can cause cancer.
That is why the EU restricts those dyes, not azo dyes in general. A report that shows the listed amines below the limit is what buyers mean by an "azo-free" report.
What is the legal limit?
In the EU, REACH Annex XVII entry 43 says textile and leather articles that may come into direct and prolonged contact with the skin must not contain azo dyes that release any of the listed aromatic amines above 30 mg/kg (30 ppm). It has applied for many years, so it is a standard request from EU buyers.
Many buyers outside the EU ask for the same test through their own restricted substance lists, and OEKO-TEX STANDARD 100 includes these amines in its criteria.
How is the azo test done?
The standard method is EN ISO 14362-1. The lab extracts the dye from the fabric, breaks the azo bonds chemically to release any amines, and measures them with chromatography (GC-MS or HPLC). A related method, EN ISO 14362-3, is used for one amine (4-aminoazobenzene) that part 1 doesn't detect reliably.
| On the report | What it tells you |
|---|---|
| Method code, e.g. EN ISO 14362-1 | Which standard method the lab used. Buyers check this matches what they asked for |
| Result per amine (mg/kg) | Each listed amine, usually "not detected" or a number |
| Limit (30 mg/kg) | The limit the result is judged against |
| Pass or fail | Whether every amine is below the limit |
| Lab name, report number and date | Who issued it and when. Reports from NABL-accredited labs carry a ULR number |
| Sample description | Which fabric, colour and lot was tested. The result applies to that sample |
Where do azo failures usually come from?
- Low-cost dyestuff of unknown origin bought by a dye house.
- A dye changed in the middle of production without testing the new shade.
- Parts other than the main fabric: prints, labels, sewing thread, trims and zip tapes.
So a report is only as good as its sample. Test the lot and colour you are actually shipping, and keep the report with that lot.
When do I need an azo test?
When your buyer asks for it, which usually means the garment is going to the EU or to a brand with its own restricted substance list. Some buyers accept a valid OEKO-TEX STANDARD 100 certificate that covers the article instead; ask them. If the buyer names a lab, use that lab.
How does TexPass help?
You order a test package on your passport and send the sample to our Tiruppur or Bangalore office. An NABL-accredited lab tests it and issues the report, and the result is added to your passport with the method code and the lab's report number. You see the result first and decide whether to publish it. TexPass is not a lab. See test packages and prices, how it works and what Lab-tested means.
Sources
We link to the official sites so you can check the details yourself. Rules and standards change, so check the source before you rely on them.
- ECHA — substances restricted under REACH (Annex XVII)The official list of REACH restrictions. Entry 43 covers azo colourants and the list of amines.
- OEKO-TEX — official siteSTANDARD 100 criteria, which include the banned amines.
General information, not legal advice. Standards and regulations change; check the official source or ask your buyer what they need. See our disclaimer.