Flammability test for clothing fabrics and US compliance
A US clothing flammability test measures flame travel at 45 degrees. Learn burn-time classes, ASTM differences, testing exemptions and certificate rules.
A fabric flammability test measures burning behaviour under specified conditions. For US general clothing textiles, 16 CFR Part 1610 uses a 45-degree test with one-second ignition and five-inch flame travel.
The result helps determine whether a fabric can be used in clothing under that standard. A Class 1 result does not mean the fabric is fireproof.
Choose the applicable fabric flammability test
Start with the product's intended use. Part 1610 covers clothing textiles within its scope, not every textile product. Children's sleepwear has separate standards in Parts 1615 and 1616. Qualifying infant and tight-fitting sleepwear remains subject to Part 1610 and/or Part 1611 as applicable. See CPSC's Flammable Fabrics Act guidance.
ASTM test names also need care. A report labelled "flammability tested" does not establish that the required US clothing test was used.
| Test | What it measures or covers | Role in US clothing compliance |
|---|---|---|
| 16 CFR Part 1610 | Clothing-textile burning behaviour using a 45-degree test | The applicable US general clothing-textile standard |
| ASTM D1230-25 | Apparel-textile flammability | Not identical to Part 1610 |
| ASTM D6413/D6413M-22 | Vertical flame resistance, reporting afterflame, afterglow and char length | Not a substitute for Part 1610 |
ASTM D1230 is not recommended for commercial-shipment acceptance testing because federal regulations require Part 1610 compliance. Its scope excludes protective clothing and sleepwear covered by separate standards. ASTM D6413 describes controlled vertical testing, not a complete assessment of real-world fire risk.
How the 45-degree flammability test works
Under Part 1610's test procedure, specimens measure 50 × 150 mm, or 2 × 6 inches. Preliminary assessment identifies the fastest-burning direction or most-flammable area. Raised-surface specimens are brushed against the lay before conditioning.
The laboratory mounts the conditioned specimen at 45 degrees. A 16 mm butane flame contacts it near the lower end for one second. Timing starts at flame impact and ends when the flame severs a stop thread, releasing its weight.
The measured travel distance is 127 mm, or five inches. That is not the specimen length. Nor is the one-second flame application the recorded burn time. Results are recorded to 0.1 second.
Testing covers the original ready-for-apparel state and prescribed refurbishment: dry cleaning followed by one laundering-and-drying cycle. Classification uses the more severe result. If the original-state result is Class 3, those samples must not proceed to refurbishment. Follow the prescribed refurbishment procedure, rather than the garment's care label. Home burning tests of fabrics do not establish compliance.
Fabric burn-time classification chart
The following table summarises §1610.4. Use it with the specimen-series rules in §1610.7, not to classify a single swatch.
| Class | Plain-surface fabric | Raised-surface fabric |
|---|---|---|
| 1: normal flammability | Burn time at least 3.5 seconds | More than 7.0 seconds, or surface flash of 7.0 seconds or less without qualifying base burning |
| 2: intermediate flammability | Not applicable | 4.0–7.0 seconds inclusive, with qualifying surface-flash base burning |
| 3: rapid and intense burning | Less than 3.5 seconds | Less than 4.0 seconds, with qualifying surface-flash base burning |
Raised surfaces complicate the chart. A rapid surface flash alone does not mean failure. Qualifying base burning means self-sustaining combustion in the ground fabric, including warp and fill yarns. Surface flash must cause that burning away from the flame-impingement point. The codes SFBB poi and SFBB poi* do not count as base burns for Class 2 or 3 determination. See Part 1610's definitions and classification rules.
Testing starts with five specimens; specified results require five more. Some outcomes are inconclusive, so a short burn time alone cannot settle every classification. CPSC guidance permits Classes 1 and 2 under the standard, cautions about Class 2 use and prohibits Class 3.
Check testing exemptions before commissioning a test
Section 1610.1(d) exempts two groups from testing:
- Plain-surface fabrics weighing at least 2.6 oz/yd², regardless of fibre.
- Plain or raised fabrics of any weight made entirely from acrylic, modacrylic, nylon, olefin, polyester, wool or combinations of those fibres.
The weight exemption does not cover raised surfaces. A polyester/cotton blend does not qualify through the listed-fibre route, though a plain-surface version could meet the weight exemption. These are testing exemptions, not exclusions from the standard. Fibre names alone also cannot replace a regulatory classification with a home burn-test chart.
Match the certificate to the clothing
For nonexempt adult or general-use apparel, a General Certificate of Conformity (GCC) must be supported by testing or a reasonable testing programme. A CPSC-accepted third-party laboratory is not mandatory for adult apparel, according to CPSC clothing guidance.
For adult apparel exempt from testing under §1610.1(d), CPSC has a narrow GCC enforcement-discretion policy. It does not waive flammability compliance or repeal certification law.
Children's apparel generally needs applicable testing through a CPSC-accepted third-party laboratory, subject to testing relief. The manufacturer or importer issues the Children's Product Certificate (CPC). A fabric testing exemption does not remove the CPC obligation, and the applicable rule still belongs on that certificate. The adult GCC policy does not apply, as CPSC explains.
RegAffairs AI's answer on US clothing flammability testing links to the regulatory sources behind this question.
For UK nightwear, make a separate assessment rather than assume US test equivalence. UK OPSS guidance identifies the Nightwear (Safety) Regulations 1985 and notes that Great Britain and Northern Ireland differences can matter.