Textile Fiber Identification by Burning Test: A Detailed Overview of Burning Behaviors

The burning test or combustion test is an experiment used to identify textile fibers by observing their burning behavior, odor, residue, and whether fibers can be extracted from the residue. Methods for distinguishing textile fibers from each other have always been of significant interest and importance in the textile industry. The essence of these methods is based on the idea that fibers can be easily identified by the odor produced during combustion, the way they burn, and the resulting ash. Non-blended textile fibers are generally easy to distinguish using these methods. However, for products made from fibers blended in specific proportions, more comprehensive identification tests—such as chemical treatments with various solvents—can be applied. 

Below are the distinguishing characteristics—odor, ash, and burning behavior—of some fibers observed through the burning test. 

General Burning Characteristics and Identifying Textile Fibers by Burning: 

• Animal Fibers (Wool, mohair, silk, angora, cashmere, alpaca, etc.) 

  • Ignite quickly, burn slowly, leave a black, brittle ash, and smell like burnt hair. 

• Plant Fibers and Regenerated Fibers (Cotton, linen, hemp, viscose, rayon, etc.) 

  • Ignite quickly, burn rapidly, leave a grayish ash, and smell like burnt paper. 

• Mineral Fibers (Asbestos, glass fiber) 

  • Do not change, melt into beads, and are odorless. 

• Acetate Fibers (diacetate, triacetate) 

  • Ignite quickly, shrink, and form a black substance, smelling like acetic acid. 

• Polyamide Fibers (PA 6, PA 6.6) 

  • First melt, then burn, leaving a hard black-brown residue that is difficult to break. The smoke is typically black with a mild, non-sharp odor. 

Fiber Types: 

• Cotton (Natural, Cellulosic-Based Fiber) 

  • Burns, does not melt. 
  • Smells like burnt paper or wood. 
  • The ash is gray, fine, and soft. 

• Linen (Natural, Cellulosic-Based Fiber) 

  • Burns, does not melt. 
  • Smells like burnt paper or wood. 
  • The ash is gray, fine, and soft. 

• Wool (Natural, Protein-Based Fiber) 

  • Burns, does not melt. 
  • Smells sharply like burnt hair or fur. 
  • Stops burning when removed from the flame. 
  • The ash forms intertwined black beads, which, when crushed, turn into smaller black beads or black powder. 

• Silk (Natural, Protein-Based Fiber) 

  • Burns, does not melt. 
  • Smells like burnt hair or fur, but the odor is less sharp than wool because silk does not contain sulfur. 
  • Stops burning when removed from the flame. 
  • The ash forms intertwined black beads, which, when crushed, turn into smaller black beads or black powder. 

• Rayon (Regenerated Cellulosic Fiber) 

  • Burns, does not melt. 
  • Smells like burnt paper or wood. 
  • The ash is gray, fine, and soft. 

• Polyester (Synthetic Fiber) 

  • Shrinks, melts, and may drip when exposed to flame. 
  • Smells like a chemical, sugary or sweet scent. 
  • The ash is black, hardened cream-colored beads that are difficult to crush. The burning polyester residue is hard and cannot be easily broken down. 

• Nylon (Synthetic Fiber) 

  • Shrinks, melts, and may drip when exposed to flame. 
  • Smells like a chemical, sugary scent, with a hint of celery. 
  • The ash is black, hardened cream-colored beads that are difficult to crush. 

• Acrylic (Synthetic Fiber) 

  • Shrinks, melts, and drips when exposed to flame. 
  • Small popping sounds occur during burning. 
  • Has a sharp, bitter odor. 
  • The ash is black, hardened cream-colored beads that may sometimes be crushable. 

• Acetate (Synthetic Fiber) 

  • Shrinks, melts, and drips when exposed to flame. 
  • Smells like burnt paper or wood, with a slight vinegar-like odor. 
  • The ash forms black, hardened cream-colored beads, which can sometimes be crushed. 

• Polypropylene (Synthetic Fiber) 

  • Shrinks and melts, forming drops that may burn and drip away from the flame. 
  • Smells like a chemical, slightly sweet odor, similar to burning plastic. 
  • The ash is minimal and can be white or light gray, soft and lightweight. 

• Polyurethane (Synthetic Fiber) 

  • Melts and drips, and burns with a blue flame. 
  • Has a sharp, chemical odor, often resembling burnt plastic. 
  • Leaves a hard, dark residue that does not crumble easily, often dark brown or black. 

• Spandex (Lycra, Elastane) (Synthetic Fiber) 

  • Shrinks, melts, and may drip when exposed to fire. 
  • Smells like burning rubber or plastic. 
  • The ash is black and remains as solid beads that do not crumble easily. 

• Modacrylic (Synthetic Fiber) 

  • Shrinks, melts, and drips when exposed to flame. 
  • Burns with a soft orange flame and smells like burning plastic. 
  • The ash forms a hard, dark, often black, residue that is difficult to break down. 

• Acrylonitrile Butadiene Styrene (ABS) (Synthetic Fiber) 

  • Melts, then burns with a yellow-orange flame and emits toxic smoke. 
  • The odor is pungent, like burnt rubber or plastic. 
  • Leaves a hard, glossy, and often dark residue, which is difficult to crush. 

• Aramid (Synthetic Fiber, e.g., Kevlar, Nomex) 

  • Burns, but with difficulty, and often self-extinguishes once the flame is removed. 
  • Emits a sharp, bitter, and slightly sweet chemical odor. 
  • The ash forms a very small amount of dark, tough residue, which is often hard and fibrous. 

• Glass Fiber (Mineral Fiber) 

  • Does not burn or melt. 
  • Odorless, as it is inorganic. 
  • The ash is hard, granular, and does not soften or change shape. 

---