Formaldehyde testing measures the amount of free and released formaldehyde in a finished textile, usually reported in milligrams per kilogram. It matters because formaldehyde is a skin sensitiser and a recognised carcinogen, and because it is used in the resin finishes that give cotton and blends their easy-care, crease-resistant and shrink-controlled properties.
Untreated fabric contains little or no formaldehyde. The finishing stage, not the spinning or the dyeing, is where it enters, so test plans target finished and resin-treated goods. For babywear and anything worn next to the skin it is one of the most commonly specified chemical tests, and failures are usually traceable to the finishing recipe or to under-curing rather than to the fibre.
Where the limits come from
In the EU, formaldehyde in textile articles that come into contact with the skin is restricted under REACH Annex XVII. OEKO-TEX Standard 100 sets class limits with the strictest for babies, then skin contact, then no skin contact, then decoration materials, and many brands adopt these class limits in their own restricted substances list. Other markets have their own national limits for children's and adult textiles. Many buyers ask for the babywear limit regardless of end use, because the test costs the same and the margin for error is wider.
Limits and methods change, so confirm the current requirement for your product class with an accredited lab or your compliance team. This is general information, not legal advice.
How the test is done
The most common method extracts the fabric in water and measures the formaldehyde that dissolves, which gives free formaldehyde. A second method exposes the fabric to warm, humid conditions and measures what is released as vapour, which is relevant for stored and packed goods. Labs report the number and the method, so your specification should state which one applies.
Results depend on the finishing recipe, the curing temperature and the time since finishing, because formaldehyde continues to release slowly. A fabric that passes on the day it leaves the finishing house may read differently after a sea voyage in a sealed container.
If the supplier offers an existing report, check the date, the method and whether the tested fabric carries the same finish as your order. A report from last season on a different finishing recipe tells you little about this shipment.
What to ask the supplier
- Which finish is applied and whether it is a low-formaldehyde or formaldehyde-free resin.
- Whether the finishing house has been curing at the specified temperature, since under-curing leaves more free formaldehyde.
- Which test method and class limit the supplier's own report refers to.
- Whether the sample tested was finished goods, or greige fabric, which would pass regardless of the finish.
How we handle formaldehyde
We agree the formaldehyde limit and method for your market and product class with you before production, then draw sealed samples from finished bulk and send them to an NABL-accredited or international lab. We check the report against the spec before loading, supervise the loading and send a weekly update. If you are unsure which class applies to your product, we offer a free 20-minute sourcing review.