Fabric Identification by The Burn Test

NATURAL FABRICS

Natural fabric is woven or knitted from fibres that occur in our natural world. All three sectors of nature; animal, vegetable and mineral produce fibres that can be used in fabric production.Vegetable, or more commonly classed cellulose-based fibres, include cotton, flax, jute, hemp and bamboo. Each fibre type is derived from a specific part of the plant such seed hair, stem, leaf, husk etc. and consist mainly of cellulose substance.

MANUFACTURED FABRICS

In the past, these fibers have been referred to as man-made, artificial or synthetic, but the term manufactured is the current accepted terminology. They can be manufactured from natural fibrous materials such as wood or bamboo pulp (rayon) or synthesized from chemicals (e.g., nylon, polyester). Manufactured fibers are relatively new on the textile scene with the earliest appearing around the beginning of the twentieth century. The most common manufactured fibres are polyester, nylon, acrylic, acetate and elastane. Manufactured fibres can be altered in their weight, texture, colour and performance more easily than natural fibres and thus offer endless possibilities.

FABRIC IDENTIFICATION TEST

Recognition and identification of fiber content in fabrics has become ex­tremely difficult because of the growing variety of types of fibers, the blending techniques in yarn and fabric construction, and the finishes that affect the appearance and hand of the fabrics. Therefore, certain tests are used for identification and verification.

BURN TEST

Burning test to recognize the composition of fabrics by the burning test, the sample of fiber, yarn, or fabric should be moved slowly toward a small flame and the reaction to the heat carefully observed. One end of the sample should then be put directly into the flame to determine its burning rate and characteristics. After it is re­moved from the flame, the burning char­acteristics should continue to be observed and the burning odor noted. After the sample has cooled, the ash should be examined for characteristics such as amount, form, hardness, and color.

MATERIAL YOU WILL NEED FOR TEST

• Fabric sample: You will need a small sample of the fabric you want to test. A sample size of 2-3 inches is usually sufficient.
• Scissors: You will need a pair of scissors to cut the fabric sample to the appropriate size.
• Tweezers or pliers: You will need a pair of tweezers or pliers to hold the fabric sample during the test. This will help to prevent burns and protect your fingers.
• Lighter or match: You will need a lighter or a match to ignite the fabric sample. A small lighter or wooden matchstick is ideal for this test.
• Ceramic or metal dish: You will need a ceramic or metal dish to collect the ash from the burned fabric sample.

THE PROCESS

• Cut a small sample of fabric from an inconspicuous area of the garment, such as the seam or hemline.
• Hold the fabric sample with a pair of tweezers or pliers.
• Use a lighter or match to ignite the fabric sample at the edge.
• Observe the behaviour of the flame and the smoke produced by the burning fabric. Note the colour, shape, and size of the flame, as well as the characteristics of the smoke.

• After the fabric has stopped burning, examine the ash and note its colour and texture.

WHAT TO OBSERVE

• Flame colour and behaviour: Observe the flame’s colour, shape, and size. Some fabrics will burn with a steady flame, while others will have a sputtering or flickering flame.
• Smoke colour and odour: Note the colour of the smoke produced by the burning fabric and any odour it emits. Some fabrics will produce white or black smoke, while others may produce a specific odour, such as burning hair or plastic.
• Burn rate: Pay attention to how quickly the fabric burns. Some fabrics will burn quickly, while others will burn more slowly.
• Ash colour and texture: After the fabric has stopped burning, examine the ash left behind. Note the colour and texture of the ash. Some fabrics will leave soft, fluffy ash behind, while others will leave behind hard, crunchy ash.

FABRIC BURN TEST RESULT

Generally, natural fiber is easily flammable. The flame doesn’t sputter. There’s a papery smell after burning. And the ashes are easy to crush.

Synthetic fiber will shrink quickly when the flame approaches. It will melt and burn slowly. There will be an unpleasant smell. And the residue will look and feel like a hard bead.

COTTON

Cotton ignites and burns quickly. The flame is round, calm and yellow. The smoke is white. After removing the flame, the fiber will continue to burn. The odor is like burning paper. The ash is dark gray and can be crushed into a powder easily.

RAYON

Rayon ignites and burns quickly. The flame is round, calm and yellow. There is no smoke. After removing the flame, the fiber will continue to burn. The odor is like burning paper. There won’t be a lot of ash. The ash that does remain will be light gray in color.

Silk

Burns slowly, but does not melt. It shrinks from the flame. It has the odor of charred meat (some say like burned hair). The residue is a black, hollow irregular bead that can be easily to a gritty, grayish-black ash powder. It is self-extinguishing, i.e., it burns itself out.

WOOL

Burns with an orange sputtery color, but does not melt. It shrinks from the flame. It has a strong odor of burning hair or feathers. The residue is a black, hollow irregular bead that can be easily crushed into a gritty black powder. It is self-extinguishing, i.e., it burns itself out. 

ACRYLIC

Acrylic shrinks quickly when the flame approaches. The flame sputters and the smoke is black. After removing the flame, the fiber will continue to burn. The ash is yellow-brown, hard and of an irregular shape.

INTRESTING FACTS

• The burning test is a good preliminary test for identifying categories of textile fibers, but it does not identify specific fibers themselves. 
• It offers valuable data regarding appropriate care and indicates general fiber groupings. 
• Problems arise when yarns or fabrics composed of two or more fibers are tested.
• Burn-in is a valuable part of assessing semiconductor device reliability and improving fabrication process steps.
• The main benefit of burn-in tests is to remove initial high potential failures in semiconductor devices, otherwise called infant mortality failures.