Determining Fiber Content of a piece of fabric

Many people only want natural fibers, like me or they sew and quilt and need specific fiber contents.  Most quilters will only use pure cotton because it gives them superior results. Use this guide to help you figure ot what it is made of.

Please read directions completely before trying.

The most reliable way is to burn a small piece of the fabric.  You will look for the three things.

• How quickly it burns
• What the residue looks like
• What it smells like

Procedure

• Cut a long thin strip of fabric about two inches long by half an inch wide, tapered at one point.

• Hold the fabric between your thumb and index finger over the sink where you can have quick access to water just in case, or hold it with a tweezers.  Using a lighter, light the tapered edge. Hold the fabric in the  flame for about four seconds. Careful here, if it is all cotton, it will burn really fast like paper.

• Watch it burn for two seconds

•   Blow out the flame

•  Observe what is left

Fabrics fall into three main categories

1. Natural, a fabric made from something that was alive at one time.  Examples are, cotton, wool, linen and silk. These burn.
2. Synthetic, a fabric made from oil and chemicals. Examples are, polyester, nylon and  acrylic.  These melt.
3. Blends, a combination of the two above.

Natural Fabrics

Cotton:  If the fabric is cotton it will burn quickly, with large flames and may be hard to extinguish.  When the flame is taken away, it continues to burn.  It resembles burning paper.  After the flame is blown out there will be a bright red afterglow around the edge of the fabric, this looks like the edges of a wood log in your fire place after the fire has gone out. If the piece has burned long enough there will be a white ash residue on the pointed edge that may fall off.  See Picture

Wool :  Wool fabric is made from  the hair of sheep. The most deciding factor here is the smell of the strip while it is burning.  It will smell like burning hair, that is the protein in it.  Many times wool will be hard to get a flame on, it burns with lots of smoke and when the flame is removed, it extinguish itself and smolders.  What is left is a black crumbly charred mess that keeps its burnt protein smell. When it is rubbed between your thumb and index finger you can turn it into a fine powder.  See Picture

Synthetic fibers, manmade from oil or chemicals

Polyester, nylon: When synthetic fibers are burnt they melt. There is no ash residue or crumbly leftovers, only hard melted clumps will remain. When the flame is put to a pure synthetic, the edge being burned will melt and roll away from the flame.  Many times beads will drop off and will be very hot to the touch, similar to a hot glue gun that has dripped. Once it has cooled, it will be hard and resemble a plastic bag that has caught on fire.  Unless you have a laboratory, it will be hard to distinguish between nylon and polyester.  Sometimes nylon melts to almost a clear finish where as polyester can melt to a black hard lump.

Blends     If a fabric is a blend it will have characteristics from both the natural and synthetic lists above. 

Cotton and Polyester blend     The fabric will burn slower than a pure cotton but will leave a stiff edge when the flame is blown out. Once it is cooled it will feel hard to the touch.  The leftovers will be black and  may flake in large pieces that do not crumble to a fine ash. The edge of the burned piece can have a hard rim around it.  The more cotton in it the more it will behave like a cotton.  If it is mostly polyester it will look melted but produce a flame when it burns.