Combustion Properties of Webbing

To identify the raw materials of the warp and weft yarns in a sample of webbing of unknown composition, extract a few strands of each and burn them individually with a lighter. Observe physical phenomena during combustion-specifically the flame characteristics, melting behavior, odor emitted, and the state of the ash-to determine the fiber type.

Cotton Fibers vs. Linen (Hemp) Fibers
Both cotton and linen fibers ignite immediately upon contact with a flame and burn rapidly with a yellow flame and blue smoke. They differ in the odor emitted and the ash produced: cotton smells like burning paper, while linen smells like wood ash. After burning, cotton leaves a tiny amount of black or gray powdery ash, whereas linen produces a small amount of off-white powdery ash.

Nylon vs. Polyester
Nylon (polyamide fiber) rapidly curls and melts into a white, gelatinous substance when near a flame. It melts, drips, and bubbles while burning but produces no flame itself; it struggles to continue burning once removed from the ignition source. It emits a celery-like odor, and the resulting light-brown melt residue is hard to crush after cooling.
Polyester (polyester fiber) ignites easily and shrinks/melts when near a flame. It burns with a yellow flame, emits black smoke while melting, and gives off an aromatic odor. The ash forms a hard, dark-brown lump that can be crushed between the fingers.

Acrylic and Polypropylene (PP)
Acrylic (polyacrylonitrile fiber) softens and shrinks when near a flame. Upon ignition, it emits black smoke and a white flame; it continues to burn rapidly after removal from the flame source, releasing a pungent, acrid odor reminiscent of burning meat. The residue consists of irregular, hard black lumps that crumble easily when crushed by hand.

Vinylon and Chlorofiber
Vinylon (polyvinyl alcohol-formaldehyde fiber) is difficult to ignite; it melts and shrinks near the flame. During combustion, a small flame appears at the tip, growing larger as the fiber melts into a gelatinous state; it emits thick black smoke and a bitter, aromatic odor. The residue forms small, black, bead-like particles that can be crushed with the fingers.

Spandex and Fluorofiber
Spandex (polyurethane fiber) melts and burns simultaneously when near a flame, producing a blue flame; it continues to melt and burn after removal from the source, emitting a distinctive, pungent odor. The residue is a soft, fluffy black ash. Fluorofiber (polytetrafluoroethylene fiber)-referred to as "fluorite fiber" by the ISO-merely melts near a flame; it is difficult to ignite and does not sustain combustion. At the edges, the flame appears blue-green as the material carbonizes and decomposes; it releases toxic gases, and the melt solidifies into hard, round black beads. In the textile industry, fluorofiber is commonly used to manufacture high-performance sewing threads.