Fabric Testing : Burn Test for fibers and other methods of fabric identification and quality checking

When you go to buy fabric in a shop, the last thing you have in mind is to burn them – but sometimes that is exactly what you have to do. The fabric burn test is one of the many methods of fabric identification that is vouched by all the textile experts out there.

For the sake of fashion, drape and visual impact you have to know exactly what you are making the garment with, which is where these fabric testing methods come to be of use.

How to test your Fabric for authenticity

By touch and feel

There are many things you can gauge about a fabric just by looking at it. You can determine the finish of fabric easily enough. You can determine the stiffness smoothness and the general feel of the fabric by running your hand over the face of the fabric.

When you try to crease the fabric, you will find cotton and linen creases and may even hold the crease, whereas wool and silk will spring back. 

Some knowledge about different aspects of fabrics like the type of fabric fibers commonly seen, type of fabric weaving used, Types of prints on fabric , fabric types, fabric finishes used, thread count of fabric, denier of fabric, identify Textured fabric names  etc. helps.

Close examination of the fabric fibers

You can look at fabric through a microscope/magnifying glass and identify the fiber correctly because of its distinctive properties.

To do this, pull a yarn in the lengthwise direction. Open up this into fibers. Keep the fibers on a slide with a drop of distilled water. Examine under a microscope. Compare to a known fiber. 

If the fabric is cotton – The finished cotton fiber will be swollen, straight, smooth and round with a shining surface. If the fabric has a nap, when you run a moistened-finger on cotton fibers, the fibers will lie down.

If the fabric is linen – the fiber will have nodes at intervals like a piece of bamboo with many joints. When you compare linen and cotton fibers, cotton fiber will be whiter in color, soft and dull whereas linen fiber will be stiffer and creamy in color.

If the fabric is silk – the fiber will be straight, very fine and smooth.

If the fabric is nylon – the fiber will have a shiny appearance

If the fabric is wool – the fiber will be springly and resilient and somewhat lustrous. If the fabric has a nap, when you run a moistened finger on the  fibers, the fibers will spring up

If the fabric is rayon – the fiber will be very fine and soft. It can resemble silk fibers but rayon fiber is not as soft or fine as silk.

Fabric burn test

This is a simple way of knowing about the fabric you have – you can do it easily enough.

What do you need to do the tests: 

A  4 cm square piece of the fabric or 4 inch long fibers from the fabric (Remember that warp and filling yarns maybe different in the same fabric and therefore should be burned separately to determine the entire fiber content of the fabric)

A  ceramic pot or a steel pot or a microwave-safe pot or aluminum foil.

A tweezer to safely examine the fiber without burning your fingers.

(☠ Cautionary words – some fabrics catch fire easily so do not forget safety precautions; do not use big pieces).

How to do fabric burn test for fabric identification

Light a match and put it close to the fabric inside the pot so that it catches fire.

Look at the flame carefully –

☝ Do the fibers shrink away from the flame?.

☝ Smell the air near the fabric as it is burning.

☝ What is the odor of the flame?

☝ When the flame is gone look at the remnants in the pot. What do you see ?

☝ What does the residue look like? Note this down.

Press very gently with a fingertip in order to feel the ashes.

Natural fabrics

These fabrics include Cellulosic fibers like cotton, linen and rayon and Protein fabrics like wool and silk. These fabric catch fire easily and burn with a yellow flame and go on to have an afterglow and leave a soft ash -grey or white as a residue.  

Cotton, Linen, Ramie, Hemp, Bamboo

These fabrics burn very quickly, vigorously on contact with fire. They burn with the smell of burning paper, leaves, or wood and leave soft grey colored ash or sometimes nothing at all.

Wool

If the fabric is wool:  The fabric does not catch fire easily and when they do, they burn slowly – the fabric even curls away from the flame. The smell of fabric burning is that of human hair burning. When you crush the remnants it feels soft and powdery. All these are the same for the wool blend as well. 

Silk

Silk shrink away from the flame. It does not continue to burn after the flame is removed. Silk burns with a smell of burning feathers and leaves an irregular shaped black bead as a residue which will easily powder to ash.

Rayon/Viscose/Tencel

If the Fabric is Rayon/Viscose: The fabric catches fire quite easily like cotton and makes a big flame soon enough. The smell of fabric burning is that of burnt leaves. When you touch the remnants they feel powdery. 

Synthetic Fabrics

This includes Polyester, Nylon, Acetate, Acrylic, Olefin and Spandex. Synthetic fabrics have high melting point but melt easily enough once that is crossed. They burn and melt when ignited and continue to burn even after the flame is removed from the fabric. They produce smoke as they burn and this may be toxic, so take all precautions. Leaves a plastic like bead as residue. 

Polyester 

If the fabric is polyester: The fabric burns very quickly. The smell of fabric burning is that of chemical vinegar or burnt plastic. There will be small hard lumps in the ashes.

Acetate and acrylic 

Fabric will burn and melt even after the flame is removed, leaving a hard bead.

Blends 

You will not be able to identify the fabric fibers accurately in blends (like polycotton) if you use the fabric burn test. 

Know more about Spandex,  Nylon and polyester here

FABRIC BURN TEST – CHART

A more detailed tabulation of the fabric burn test results

More cautionary words – ☠ We are dealing with fire, so do heed these important points before you attempt burning.

Wear non-inflammable clothes when using the test. If you are a kid make sure an adult knows about this and comes to oversee the operation. Use these tests on flammable materials with utmost caution. Keep damp woolen cloth nearby to put out a fire. Keep hair out of flame and do not allow the burning material to touch skin.

The result of fabric burning test may prove ambiguous sometimes when different fibers are twisted together. Different finishes used on the fabric also may result in varying results

Other Industrial Fabric tests

Chemical solubility tests

These are tests that help to determine the fiber content of a fabric. Here solvents are used to identify one fiber from another. Reactions of fibers to common acid and alkaline solutions are used in these tests. Acetate fabric will dissolve in acetone nail polish remover.

Stain tests to identify synthetic fibers 

These are tests used to identify fibers using stains and dyes. Fibers are dyed or stained with reagents.

Specialized machines

An infrared spectrophotometer is used to separately identify synthetic fibers in a blended fabric.

Tensile strength tests

These are tests done during fabric development and manufacturing – strip tensile test, grab tensile test and wide width tensile test are the different tests used. In the strip tensile test, the fabric is pulled from both ends and a tensile load is applied to test its tensile strength. Grab tensile test and wide width tensile tests are used for industrial fabrics.

Fabric Bow and skew

There are machines to test the way filling yarns in a fabric lie in an arc. In the fabric, warp yarns are usually straighter than filling yarns since filling yarns may have more tendency for bow and skewness. The selvage of the fabric runs parallel to the warp direction. 

Standard fabric tests

Here are the major standard fabric tests used by American Association for Textile Chemists and Colorists to identify different characteristics.

• Tear resistance tests – Tongue test and Elmendorf test are the two tests used to test the resistance of fabrics Fabric count of the woven fabric.
• The width of woven fabric .
• The resistance of Apparel fabrics to pilling.
• Test method for flammability of fabrics.
• Colorfastness testing.
• Creasing in fabrics.
• Thickness of fabrics.
• Stretch properties of fabrics woven from stretch yarns.
• Abrasion resistance of textile fabrics.
• Standard specification for knitted fabrics.
• Water repellency and resistance.
• Weather resistance. 
• Identification of finishes in fabrics.
• Insect pest deterrents on fabrics.
• Wrinkle recovery  of fabrics.
• Resistance to yarn slippage at the sewn seam in Upholstery fabrics; The stiffness of fabric by the circular bend procedure; Bursting strength and elongation of sewn seams of knit or woven stretch textile fabrics; Grayscale for staining; Grayscale for color change; Bond strength of bonded fabrics; Light blocking effect of curtain fabrics; Smoothness of seam. 

Electrostatic clinging of fabrics; Colour measurement of textiles; Antifungal and Antibacterial finishes in textiles; Oil repellency; Evaluation of wetting agents.

Read more : This document has some more tests that you can do on your fabrics and also documents of American Society for Testing Materials, Annual Book of ASTM Standards published yearly by the ASTM, Philadelphia, PA.

Related posts : Fabric Glossary; What is fabric : 20 FAQ on quality yardsticks for Fabric ; How to buy fabric.