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A lighter and a pair of tweezers can tell you a lot about a fabric. Hold a frayed edge to a flame, and cotton, wool, and polyester each respond uniquely. That makes the fabric burn test one of the fastest fiber screens in textile quality control. But it is also one of the most misused.
Regulators, customs authorities, and retail buyers do not accept a burn test as proof of fiber content or flammability. With the Federal Trade Commission (FTC) penalizing mislabeled textiles and a core ASTM fiber method withdrawn, the gap between a quick screen and defensible textile testing matters more than ever.
Key Takeaways
- The burn test screens; it does not certify. It separates plant, animal, and synthetic fibers, but it cannot quantify blends or substantiate a label.
- ASTM D276 is no longer active. ASTM withdrew it in 2021, and laboratories now rely mainly on AATCC TM20 for fiber identification.
- Fiber content shapes flammability rules. Fabrics made entirely of certain synthetics or wool are exempt from 16 CFR 1610 testing, so an accurate fiber ID can decide whether testing applies.
What a Flame Reveals About Fiber
The test reads four signals: behavior near the flame, smoke odor, self-extinguishing behavior, and residue. Together, they point to one of three fiber families.
- Cellulosic fibers: Cotton, linen, hemp, rayon, viscose, modal, and lyocell ignite fast, smell like burning paper, and leave soft gray ash.
- Protein fibers: Wool, silk, cashmere, and alpaca burn slowly, often self-extinguish, smell like burning hair, and leave crisp, crushable ash.
- Synthetic fibers: Polyester, nylon, acrylic, olefin, and spandex shrink from the flame, melt, and leave a hard bead.
The test identifies fiber, not weave. So, a satin can burn like silk, polyester, or nylon. “Bamboo” fabric is usually rayon made from bamboo pulp, which the FTC requires sellers to label as rayon.
How to Perform a Fabric Burn Test
Molten synthetics can drip and cause contact burns, so the test is to be performed over a ceramic or metal tray, in a ventilated space, with water nearby. A 2.5 cm (1 in) sample, metal tweezers, and a lighter complete the setup.
- Prepare the sample
Fray one edge to expose fiber ends. Test warp and weft yarns separately, since they may differ.
- Approach the flame
Bring the edge slowly toward the side of the flame. Note whether it curls away or melts.
- Enter the flame
Hold it in the flame for 2 to 3 seconds. Note ignition speed, flame color, smoke, and dripping.
- Remove the sample
Note whether it keeps burning, glows, or self-extinguishes.
- Note the odor
Waft the smoke by hand rather than inhaling directly.
- Examine the residue
Once cool, crush it between gloved fingers. Soft ash points to natural fibers; a hard bead points to synthetics.
Fabric Burn Test Chart: 12 Common Fibers
The chart below summarizes typical burn behavior for common textile fibers.
| Fiber | Family | Near and in Flame | Odor | Residue | After Removal |
|---|---|---|---|---|---|
| Cotton | Cellulosic | Ignites fast; steady yellow-orange flame | Burning paper | Soft, light gray ash | Keeps burning; afterglow |
| Linen | Cellulosic | Like cotton; slightly slower to ignite | Burning grass or hay | Soft gray ash | Keeps burning |
| Rayon, viscose, modal, lyocell | Regenerated cellulosic | Ignites fast; may flare | Burning paper | Very little soft ash | Keeps burning |
| Wool | Protein | Curls away; burns slowly and sputters | Burning hair | Crisp, dark, crushable ash | Self-extinguishes |
| Silk | Protein | Curls away; burns slowly | Burning hair | Fine dark ash; crushes easily | Usually self-extinguishes |
| Cashmere, alpaca, mohair | Protein | Like wool | Burning hair | Crisp, dark, crushable ash | Usually self-extinguishes |
| Polyester | Synthetic | Shrinks and melts; black smoke | Sweet chemical | Hard, round, dark bead | Often self-extinguishes |
| Nylon | Synthetic | Shrinks and melts quickly; drips | Celery-like | Hard, smooth, gray or tan bead | Often self-extinguishes |
| Acrylic | Synthetic | Melts and flares; burns readily | Harsh, acrid | Hard, irregular black bead | Keeps burning |
| Olefin (polypropylene) | Synthetic | Shrinks, melts, and burns | Paraffin or candle wax | Hard tan bead | Keeps burning |
| Spandex (elastane) | Synthetic | Melts and fuses; burns slowly | Chemical or rubber-like | Soft, sticky mass | Keeps burning |
| Acetate | Modified cellulose | Melts and burns fast; may flare | Vinegar | Hard, irregular dark bead | Keeps burning |
Note: Dyes, coatings, and flame-retardant finishes can alter these results.
Where the Burn Test Falls Short
Blends send mixed signals: A cotton-polyester fabric may leave both soft ash and hard beads, but an 80/20 blend and a 60/40 blend can look alike in a flame. Flame-retardant finishes can make cotton self-extinguish, and odor perception varies from one tester to the next. That is why the burn test carries no weight in compliance work. Fiber percentages, label claims, and flammability classes all rest on standardized laboratory methods.
| Method | What It Answers | Typical Use |
|---|---|---|
| Burn test | Which fiber family is present | Fast screening, incoming goods checks |
| Fiber microscopy and solubility (AATCC TM20) | Which generic fiber is present | Confirming identity, including natural fiber species |
| Infrared spectroscopy (FTIR) | Polymer type | Distinguishing similar synthetics through polymer analysis |
| Chemical dissolution (AATCC TM20A, ISO 1833) | Fiber percentage by weight | Label claims, customs, supplier disputes |
| Flammability testing (16 CFR 1610) | Flammability class | US apparel compliance and certification |
The Regulatory Stakes: Fiber Content and Flammability Rules
ASTM D276 Withdrawn, Reinstatement Underway
Many online guides still cite ASTM D276 for fiber identification. ASTM withdrew D276-12 in January 2021, and in September 2025, opened work item WK96331 to reinstate it. Its quantitative companion, ASTM D629, was withdrawn in 2024. Laboratories now rely mainly on AATCC TM20, AATCC TM20A, and ISO 1833, which the ISO is revising.
CPSC 16 CFR 1610: Clothing Textiles
The Consumer Product Safety Commission (CPSC) sorts clothing fabrics into three classes by burn speed. Class 3 fabrics burn rapidly and intensely and cannot be used in clothing. The test mounts a 2×6-inch specimen at a 45° angle and applies a 16 mm flame for one second.
Two groups of fabrics are exempt from testing:
- By weight: Plain-surface fabrics of at least 2.6 oz per square yard (88.2 g/m²), regardless of fiber content
- By fiber: Fabrics made entirely of acrylic, modacrylic, nylon, olefin, polyester, wool, or a combination of these
The fiber exemption is where identification and flammability meet. A fleece made entirely of polyester qualifies; the same fleece with undisclosed rayon does not. Adult apparel requires a General Certificate of Conformity; however, third-party flammability testing is optional. Children’s apparel requires testing at a CPSC-accepted third-party laboratory.
Need 16 CFR 1610 flammability testing?
Submit a lab request to find an accredited testing partner.
Children’s Sleepwear: 16 CFR 1615 and 1616
Sleepwear in sizes 0 through 14 faces a stricter vertical flame test under 16 CFR 1615 and 1616. Garments that qualify as “infant” or “tight-fitting” follow 16 CFR 1610 instead.
FTC Textile Fiber Products Identification Act
The FTC’s labeling guide requires labels to name each fiber at 5% or more of product weight. Textile World reports that the FTC allows a 3% tolerance. The stakes are real: in 2022, Kohl’s and Walmart agreed to pay $5.5 million in combined civil penalties for marketing rayon products as bamboo.
EU Textile Labelling Regulation
Regulation (EU) 1007/2011 governs fiber names and composition labels in the EU. The Commission targeted mid-2026 for a revision adding digital labels, and in June 2026 retail and industry groups jointly urged it to proceed. The 2011 rules remain in force until a formal proposal is adopted.
Sourcing the Right Laboratory Partner
Fiber analysis and flammability testing require calibrated equipment, trained analysts, and, for children’s products, CPSC acceptance. Laboratory testing typically comes into play for label substantiation, blend percentages, customs classification, flammability certification, exemption confirmation, and supplier disputes.
Contract Laboratory connects manufacturers, importers, brands, and QA teams with accredited textile testing laboratories and consumer product testing providers. Laboratories in the network are searchable through Find a Lab.
Submit a textile testing request to receive quotes and proposals from qualified laboratories.
This article was created with the assistance of Generative AI and has undergone editorial review before publishing.
Sources and Further Reading
- ASTM D276-12 (withdrawn 2021) and ASTM WK96331 reinstatement
- ASTM Subcommittee D13.51 jurisdiction
- AATCC TM20
- ISO 1833-1:2020 and ISO/DIS 1833-1
- CPSC Clothing Business Guidance.
- CPSC accepted lab search
- FTC Threading Your Way and FTC bamboo cases
- FTC Kohl’s and Walmart release
- Textile World on textile labeling (December 2025)
- European Commission review of Regulation 1007/2011 and EuroCommerce joint call (June 2026)
Frequently Asked Questions (FAQs)
It reliably separates cellulosic, protein, and synthetic fibers. It is less reliable for blends, treated fabrics, and similar synthetics.
Natural fibers burn to soft ash. Synthetics shrink from the flame, melt, and leave a hard bead that will not crush.
Cotton burns steadily, smells like burning paper, and leaves soft gray ash. Polyester shrinks from the flame, melts, gives off a sweet chemical odor, and leaves a hard bead.
Burning nylon gives off a faint celery-like odor. It also melts quickly and leaves a hard, smooth bead.
Both smell like burning hair and usually self-extinguish. Wool leaves coarser ash, while silk leaves a finer residue that crushes easily.
No. Laboratories dissolve one fiber and weigh the remainder, following methods such as AATCC TM20A or ISO 1833.
No. ASTM withdrew it in 2021. A reinstatement effort began in 2025, and laboratories currently rely on AATCC TM20 for fiber identification.
No. 16 CFR 1610 exempts plain-surface fabrics of 2.6 oz per square yard or more and fabrics made entirely of certain fibers, including polyester, nylon, acrylic, and wool.