How do I identify fibers in a fabric sample by burn test?

If you have a fabric with unknown fiber content a burn test can help you determine what it is made of. Please take precautions when doing a burn test! Burn tests take practice but with experience you will get better at identifying the fibers.


Procedure:
Take a small snip of fabric approximately 4” long and hold it with tweezers over a pie tin, aluminum foil or another noncombustible surface. Light the end of the fabric.


Observe:
if the fibers melt or burn
if it lights easily or shrinks away from the flame
the smell of the burning sample
if the flame goes out on it’s own
the residue left once extinguished


Characteristics of different fibers:

Natural Fibers:
Cotton- burns, odor of burning paper or leaves, can blow out the flame, soft gray ash left over
Hemp- similar to cotton
Linen- similar to cotton, individual fibers are long (cotton has shorter fibers), takes longer to ignite than cotton
Rayon- burns rapidly leaving a slight ash, smell of burning leaves
Silk- burns but will shrink from the flame, self extinguishing, odor of charred meat or hair, black bead left over that crumbles into gritty black powder
Wool- burns but hard to ignite, smells like burning hair, self extinguishing, black bead left over that crumbles into gritty black powder


Manufactured Fibers:
Acetate- smells like burning paper and vinegar, hard dark bead left over
Acrylic- ignites easily, black smoke when burning, acrid smell, hard irregular bead left over
Nylon- melts and then burns if you keep the flame on it, smells like burning plastic
Polyester- sweet chemical odor and black smoke, hard light colored bead that becomes darker
Spandex- (lycra) burns and melts, chemical odor, soft black ash left over


Notes:
Blends of fibers will have a combination of their individual characteristics. If you suspect the warp and the weft fibers in a woven are different you can pull them apart and burn a bundle of each separately.
Finishes on the fabric can make it difficult to determine the fiber.
Acetone (in nail polish remover) will dissolve acetate.
Fiber-Etch will dissolve plant fibers (cotton, linen, rayon) and can be used to determine if your sample is a blend.
Bleach will dissolve wool.