The burn test is a simple, somewhat subjective test based on the knowledge of how particular fibers burn. Be prepared to note the following when testing your fibers:
• Do the fibers melt and/or burn?
• Do the fibers shrink from the flame?
• What type of odor do the fumes have?
• What is the characteristic(s) of any smoke?
• What does the residue of the burned fibers look like?
The burn test is normally made on a small sample of yarns or thread which are twisted together. Since the fiber content of yarns used in one direction of a fabric are not always made up of the same fibers used in the other direction, warp and filling yarns should be burned separately to determine the entire fiber content of the fabric.
This test is very helpful in determining whether a fabric is made from synthetic or natural fibers, but it is not foolproof and the characteristics observed during the burning test can be affected by several things. If the fabric /yarn contain blends of fibers, identification of individual fibers can be difficult. Two or three different kinds of fibers burned together in one yarn may also be difficult to distinguish. The odor and burning characteristics exhibited may be that of several fibers, thus making your results difficult to analyze. Finishes used on the fabric can also change the observed characteristics.
• Pull a small sample of at least six to eight yarns from your fabric about 4 inches long, and twist them together into a bundle about 1/8 inch in diameter. You can also use a small snippet of the fabric if you only need to determine whether it is a synthetic or natural fiber fabric and you are not seeking to determine the specific fiber(s) that make up the fabric.
• Hold one end of the bundle with tweezers over a sink or a sheet of aluminum foil (about 10 to 12 inches square) to protect your working area. If the sample ignites it can be dropped into the sink or on the foil without damage.
Use either a candle or a match (automatic lighters work well) as your flame.
PLEASE USE EXTREME CAUTION WHEN TESTING!
Some fibers are slow in igniting, but then burn quickly. Others can burn hot and produce a painful burn if caution is not maintained.
Be extremely careful to keep your hair out of the flame.
Be very certain that you are not wearing flammable materials when testing.
Do not stand anywhere near any flammable materials.
Potential Test Results
Natural, Organic & Manmade Fibers
In general, if the ash is soft and the odor is of burning hair or paper, the fabric is a natural fiber. Cellulosic fibers (cotton, linen and rayon) burn rapidly with a yellow flame. When the flame is removed, there is an afterglow, then soft gray ash.