Interlining is a textile. It is dyed, finished, coated. Formaldehyde shows up from resin finishes and some older chemistries meant to keep a collar crisp. Azo dyes that can split into listed amines show up from cheap colour. A fusible that passes peel and fails an infant RSL is still a failed lot.
TrimGem treats interlining certificates like any other trim: article, colour, class, expiry.
Why fusibles get tested
OEKO-TEX® STANDARD 100 (Hohenstein and partners) covers components including zippers, buttons, sewing thread and interlinings. Hundreds of substances are in scope. For textile interlinings the practical pack is: banned azo colourants, formaldehyde, colour fastness, pesticide residues where natural fibres warrant it.
Azo / carcinogenic amines
Listed azo colourants can reduce to carcinogenic aromatic amines. STANDARD 100 uses ISO 14362 methods; each listed amine is typically capped at ≤20 mg/kg (tighter than some national 30 mg/kg figures). GB/T 17592 is the Chinese method language you will see on local reports. Dyehouse control is the fix, not a wash at the garment factory.
Formaldehyde by class
Formaldehyde irritates; it is also a legal number. OEKO-TEX classes (indicative):
| Class | Typical use | Formaldehyde |
|---|---|---|
| I | Infants | 16 mg/kg |
| II | Direct skin | 75 mg/kg |
| III | No direct skin | 300 mg/kg |
| IV | Decoration | 300 mg/kg |
Chinese ecological talk for interlinings often aligns with ≤75 mg/kg (Class II). Shirt-collar resins are the usual suspect. Low-formaldehyde / formaldehyde-free hot-melts and finishes exist; they are a purchase, not a hope. Factory gates still use GB/T 2912.1 (water extraction) on lots.
Infant garments need Class I thinking even on a hidden canvas. “Hidden” is not a chemical shield.
Other lines that appear
Appendix 4-type lists: lead and cadmium caps, pentachlorophenol, six phthalates as a sum ≤0.1%. Appendix 6 adds environmental performance (PFAS, BPA at tight limits, and so on). APEO, extractable metals (sweat simulants), organotins, chlorophenols, chlorinated paraffins, and pH (Class I about 4.0–7.5; Class II 4.0–8.0; III/IV to 9.0) show up on full packs.
Metal trims in the same garment have their own heavy-metal story. Do not file a snap report as an interlining report.
What to demand
- Low-formaldehyde adhesive and finish; lot test GB/T 2912.1.
- Azo control on dyed bases (GB/T 17592 / ISO 14362).
- STANDARD 100 (or a brand RSL of equal bite) on the fusible SKU, renewed yearly.
- REACH / POPs / CPSIA as the market requires — OEKO-TEX is evidence, not a law by itself.
EU programs often want the pack: azo, formaldehyde, APEO, extractable metals, phthalates, class by wearer age.
Write class (I–IV), methods, and colourways. A white 30 g PES fusible and a black dyed woven canvas are not one certificate. Hidden layers still sit next to skin in a shirt. Spec them as if someone will test the collar, because they will.