Using the burn test method, it is possible to differentiate between different types of fibers based on their physical and chemical properties. By observing the behavior of fibers near a flame, including their burning speed, flame color and characteristics, emitted odor, ability to continue burning after being removed from the flame, the speed of residual combustion, and the color and condition of the ashes, one can roughly determine the general category of the fiber sample being burned, such as cellulose fibers, protein fibers, or synthetic fibers. With sufficient experience and combined sensory identification methods, common fiber types can be reliably identified.
Polyester fiber
Is easy to ignite, and it melts and shrinks when near flames. It emits black smoke while melting, with yellow flames and a fragrant smell. The ashes after burning are dark brown lumps that can be crushed with fingers.
Cotton Fiber
Burns readily upon contact with flame, burns quickly with a yellow flame, emits odor; produces light gray-white smoke, can continue to burn after being removed from flame, and may spark when blown out, though briefly; burns leaving behind fine, soft gray ashes, with charred parts appearing as black.
Flax Fiber
Burns very quickly, softens but does not melt or shrink, produces a yellow or blue flame with a smell of burning grass; continues to burn rapidly after being removed from flame; leaves minimal ash, appearing as light gray or white powdery ash.
Wool
Does not immediately catch fire upon contact with flame, curls back and smolders, eventually ignites and burns with a yellow-orange flame; burns slower than cotton, stops burning when removed from flame, does not easily continue burning, emits a smell similar to burning hair or feathers; ashes are irregular dark brown-black brittle lumps that crush easily when pressed, with a considerable amount of ash and a characteristic odor during burning.
Silk
Burns slowly, melts and curls, burns in a compact mass with a smell of burning hair; may sometimes sparkle when removed from flame, burns slowly and may self-extinguish; ashes are black-brown brittle small balls that crumble easily when pressed.
Viscose (Rayon) Fiber
Burning characteristics are similar to cotton, but burns slightly faster with less ash; sometimes does not maintain original shape, may hiss lightly during burning.
Nylon
Shrinks away from flame, melts and burns to form a transparent, gel-like substance with small bubbles when in contact with flame.
Acrylic
Melts and burns simultaneously, burns quickly with a bright white flame, sometimes with slight black smoke; emits a fishy or peppery odor similar to burning coal tar; continues to burn after being removed from flame, burns slowly; ashes are irregular brittle black-brown balls that crush easily when pressed.
Modacrylic
Expands into a round shape near flame, then shrinks and melts; burns slowly with a yellow or blue flame in the flame; melts and burns when removed from flame, slowly extinguishes itself; emits a distinctive irritating odor during burning; ashes are white adhesive lumps.
