How To Test for Fabric Content

Now you have it!--a beautiful piece of fabric. But how can you tell the fiber content? Aside from having a label or bill of sale, you'll have to test it. The burn test is a simple test where you burn a sample of the fibers and observe characteristics as they burn. This can give you a general idea of the fiber content.
Testing Procedures
The burn test is made on a small sample of fibers twisted together. You will need to take this sample from the edge ofyour fabric.
Select your sample
Since the yarns used in one direction of a fabric are not always geprised of the same fibers used in the other direction, warp and filling yarns should be burned separately. Also, do not take your sample from the selvege. On some fabrics (woolens especially) the selvege contains stabilizing fibers that are not contained in the fabric itself.
Set Up the Test
First cut a piece of fabric about 4 inches by 1 inch. Unravel the sample to collect the fibers for your test. Next,take least six to eight yarns about 4 inches long, and twist them together into about a 1/8 inch in diameter bundle. Set up your test area with something to hold the sample while it burns and a safe surface to hold the ashes and/or protect the area below from burning. A tweezer or two coins held together can be used to hold the end of the bundle. A sheet of aluminum foil spread below the test area can be used to protect. If the sample ignites it can be dropped on the foil without damage. Use either a candle or match to provide the flame.
Conduct the Burn
Ignite the sample and observe as it burns. These are the characteristics to look for:
Do the fibersburn and/or melt?
Do the fibers shrink from the flame?
What type of odor do the fumes have?
What is the color of any smoke?
What does the residue of the burned fibers look like?
Natural Fiber

Cotton: Burns, but does not melt. Has the odor of burning paper, leaves, or wood. Residue is a fine, feathery, gray ash.
Hemp: Same as cotton
Linen: Same as cotton
Ramie : Same as cotton
Rayon : Same as cotton
Silk: Burns, but does not melt. Shrinks from the flame. Has the odor of charred meat. Residue is a black, hollow irregular bead that can be easily to a gritty black powder. Is self-extinguishing, i.e., it burns itself out.
Wool, and other Protein Fibers: Burns, but does not melt. Shrinks from the flame. Has a strong odor of burning hair. Residue is a black, hollow irregular bead that can be easily crushed into a gritty black powder. Is self-extinguishing, i.e., it burns itself out.

Man-made Fibers