A simple method for identifying the composition of clothing fabrics is the burning test. The procedure involves pulling a strand of fabric—containing both warp and weft threads—from the seam allowance of the garment, igniting it with fire, observing the characteristics of the burning flame, smelling the odor emitted by the burning fabric, and examining the residue left behind after combustion. By comparing these observations with the fabric composition listed on the garment’s label, you can determine whether the fabric’s composition matches the information provided on the label, thereby verifying the authenticity of the fabric’s claimed composition.
First, cotton fibers and hemp fibers
Cotton fibers and hemp fibers burn rapidly when placed near a flame, producing yellow and blue smoke. The key differences between the two in terms of burning odor and post-burn ash lie in their respective smells: cotton burns with a paper-like scent, while hemp leaves behind an ash smell reminiscent of burnt grass. After burning, cotton produces very little fine ash—black or gray in color—whereas hemp yields a small amount of whitish-gray fine ash.
Second, wool fibers and silk
The hair is on fire, emitting smoke and bubbling as it burns. It burns relatively slowly, giving off the smell of scorched hair. The burnt ashes are mostly glossy, black, spherical particles that can be easily crushed between your fingers. When ignited, the silk-like fibers curl up into a compact ball, burning even more slowly, accompanied by a hissing sound and the characteristic odor of charred hair. They burn down to a dark-brownish ash that crumbles instantly when pinched between your fingers.
Third, nylon and polyester
The scientific name for nylon is polyamide fiber. When exposed to a flame, it quickly curls up and melts into a white gel. In the molten state, it burns with droplets and bubbles, producing no visible flame during combustion. The remaining residue is difficult to rekindle and emits a celery-like fragrance. After cooling, the light-brown melted material is not easily broken. The scientific name for polyester is polyethylene terephthalate fiber. It ignites readily and begins to melt and shrink upon approaching a flame. During combustion, the side that’s melting emits black smoke, while the burning flame itself appears yellow and gives off a pleasant aromatic odor. The ash left behind after burning is a hard, dark-brown lump that can be easily twisted with your fingers.
Acrylic and polypropylene
Acrylic fiber, formally known as polyacrylonitrile fiber, softens and melts when exposed to heat, shrinking and deforming. When ignited, it emits thick black smoke, with a white flame. Once removed from the flame, it continues to burn rapidly, giving off a pungent, sour odor reminiscent of burning meat. When completely burned, it leaves behind irregular, hard, black lumps that are easily twisted and broken. Polypropylene fiber, also known as polypropylene fiber, melts and shrinks upon exposure to flame; it is highly flammable. When removed from the flame, it burns slowly, emitting thick black smoke. The top of the flame appears yellow, while the base turns blue, releasing a petroleum-like odor. The resulting ash consists of hard, round particles that are light yellow-brown in color and easily become brittle when twisted.
V. Polyvinyl chloride and polyvinyl chloride
The scientific name for vinylon is polyvinyl alcohol formaldehyde fiber. It is not easily ignited; when brought near a flame, it melts and shrinks. Once ignited, the flame at the top becomes larger, and the melted fiber turns into a gel-like substance, emitting thick black smoke with a bitter odor. After burning, only small, black, bead-like particles remain—particles that can be easily crushed by finger pressure. As for chloroprene fiber, it is also not easily combustible. When the flame is extinguished, it turns yellow, while the lower end emits greenish-white smoke accompanied by a pungent, acrid, acidic odor. After burning, the residue is a hard, irregular lump of dark-brown ash that is difficult to twist or crush with fingers.
Sixth, spandex and spandex.
The scientific name for spandex is polyurethane fiber. When exposed to a flame, the side that melts near the flame’s edge will burn with a blue flame. The portion farther from the flame continues to melt and burn, emitting a distinctive, irritating odor. After burning, the residue leaves behind a soft, fluffy black ash. The scientific name for fluoroplastics is polytetrafluoroethylene fiber; the ISO organization refers to it as “fluorite fiber.” Near a flame, fluoroplastics merely melt without easily igniting or burning. The flame’s edge becomes carbonized in a bluish-green hue, and the material melts and decomposes, releasing toxic gases. The melted material forms hard, round, black beads. In the textile industry, fluorofibers are commonly used to produce high-performance sewing threads.
7. Viscose fiber and cuprammonium fiber
Viscose fiber is highly flammable, burns rapidly, produces a yellow flame, and emits a smell reminiscent of burnt paper. It leaves little ash behind—just a smooth, twisted fine powder that’s light gray or gray in color. Cuprammonium fiber, commonly known as "tiger cotton," ignites readily when brought near a flame; it burns quickly with a yellow flame and gives off an ester-like odor. After burning, it leaves very little ash—only a small amount of dark gray residue.