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 yarns from the seam of the garment, igniting it, observing the flame, smelling the odor emitted after burning, and examining the residue. This helps determine if the composition matches the fabric composition listed on the garment's durability label, thus verifying the authenticity of the fabric.
Cotton and Linen Fibers
Both cotton and linen fibers ignite immediately upon contact with a flame, burning rapidly with a yellow flame and blue smoke. The difference lies in the odor emitted during combustion and the ash produced: cotton smells like paper, while linen smells like wood ash; after burning, cotton produces very little powdery ash, which is black or gray, while linen produces a small amount of grayish-white powdery ash.
Wool and Silk
Wool smokes when exposed to fire, bubbles when burning, burns more slowly, and emits a burnt hair smell. The ash is mostly shiny black spherical particles that crumble easily when pressed with a finger. Silk shrinks into a ball when exposed to fire, burns slowly with a hissing sound, and emits a smell of burning hair. After burning, it forms small, dark brown, spherical ash that crumbles easily when rubbed between the fingers.
Nylon and Polyester: Nylon, scientifically known as polyamide fiber, rapidly shrinks and melts into a white, gel-like substance when near a flame. It melts and drips in the flame, bubbling, and burns without a flame. It does not continue burning after being removed from the flame and emits a celery-like smell. The cooled, light brown molten material is not easily crushed. Polyester, scientifically known as polyester fiber, is easily ignited. It melts and shrinks when near a flame, and burns with a yellow flame while melting and emitting black smoke. It emits a fragrant odor, and the ash is a hard, dark brown lump that can be crumbled between the fingers.
Acrylic and Polypropylene: Acrylic, scientifically known as polyacrylonitrile fiber, softens and shrinks when near a flame. It emits black smoke and a white flame when ignited. After being removed from the flame, it burns rapidly, emitting a pungent smell of burning meat. The ash is an irregular, hard, black lump that crumbles easily when rubbed between the fingers. Polypropylene fiber, scientifically known as polypropylene fiber, melts and shrinks near a flame, is flammable, burns slowly with black smoke after being removed from the flame, has a yellow upper flame and a blue lower flame, emits a petroleum smell, and leaves hard, round, light yellowish-brown granules that are easily crumbled by hand.
Vinylon and Chlorinated Fiber
Vinyl cellulose fiber, scientifically known as polyvinyl alcohol formaldehyde fiber, is not easily ignited, melts and shrinks near a flame, and burns with a small flame at the tip. Once the fiber has melted into a gel-like substance, the flame enlarges, producing thick black smoke and emitting a bitter, fragrant odor. After burning, it leaves small black bead-like particles that can be crushed by fingers. Chlorinated Fiber, scientifically known as polyvinyl chloride fiber, is difficult to burn, extinguishes immediately after being removed from the flame, has a yellow flame with greenish-white smoke at the lower end, emits a pungent, acrid, and acidic odor, and leaves irregular, hard, dark brown lumps that are not easily crushed by fingers.
Spandex and Fluorinated Fiber
Spandex fiber, scientifically known as polyurethane fiber, melts and burns while near a flame, with a blue flame. It continues to melt and burn after being removed from the flame, emitting a peculiar, pungent odor, and leaves soft, fluffy black ash. Fluorine fiber, scientifically known as polytetrafluoroethylene fiber, is called fluorite fiber by the ISO organization. It melts near a flame, is difficult to ignite, and does not burn. The edge of the flame shows a bluish-green carbonization. Upon melting, it decomposes, releasing toxic gases. The molten material forms hard, round, black beads. Fluorine fiber is commonly used in the textile industry to manufacture high-performance sewing thread.
VII. Viscose Fiber and Cuprammonium Fiber: Viscose fiber is flammable and burns very quickly. The flame is yellow, emitting a burning paper odor. It leaves little ash, which is a smooth, twisted, ribbon-like, light gray or grayish-white fine powder. Cuprammonium fiber, commonly known as tiger cotton, burns immediately near a flame, burns quickly, has a yellow flame, emits an ester acid odor, and leaves very little ash, only a small amount of grayish-black ash.
