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

Touch and feel

There are many things you can gauge about a fabric just by looking at it. You can determine the finish of a 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. Some knowledge about different aspects of fabrics like the type of fabric fibers commonly seen, type of fabric weaving used, fabric patterns , fabric types, fabric finishes used, identify fabric with texture etc. helps

Close examination of the fabric fibers

You can look at fabric through a microscope 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 is linen – the fiber will have nodes at intervals  like a piece of bamboo with many joints

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

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

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

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 odour 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 Protien 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 on contact with fire. They burn with the smell of burning paper, leaves, or wood and leave soft grey coloured ash.

Wool

If the fabric is wool:  The fabric do not catch fire easily. 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 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 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.

Know more about SpandexNylon and polyester here

FABRIC BURN TEST – CHART

A more detailed tabulation of the fabric burn test results

Types of fabricReaction to flameBurning behaviourOdour of flameAfter the flame is overType of Ash
Cotton, Hemp, RamieDoesnot shrink away from flame; Ignites easily on contact with flameBurns rapidly with a yellow flame and light grey smoke.Burning paper.
Continues to burn, there is an after glow.Soft Grey powdery smooth ash
LinenDoesnot shrink away from flame; Ignites easily on contact with flameBurns rapidly with a bright yellow flame and light grey smoke.Burning paper.
Continues to burn, there is an after glow.Soft Grey powdery smooth ash
Rayon, TencelDoesnot shrink away from flame; Ignites easily on contact with flameBurns rapidly with a yellow flame and light grey smoke.Burning wood or paper.
Burns slowly without flame with slight meltingNo ash
WoolShrinks away from flame.Burns slowly with an orange colour but doesnot melt; small flickering flameStrong odour of Burning hair or featherMay self extinguish ie it burns itself outCrushable black bead that turns to ash.
SilkShrinks away from flame.Burns slowly sizzles but doesnot meltBurning hair.
May self extinguishCrushable black bead that turns to ash.
Acrylic, OlefinMelts and pulls away from the flame.Melts and burn rapidly with hot sputtering black flameAcrid Chemical odour (Fishy odour)Continues to burn and melt.Forms irregular small beads in black /tan
ModacrylicMelts and pulls away from the flame.Difficult to ignite; Melts and burnChemical odourSelf extinguishes with white smoke.Forms small hard beads in black
SpandexMelts but doesnot pull away from the flame.Melts and burnMusty Chemical odourContinues to burn and melt.Soft sticky black ash.
PolyesterMelts and pulls away from the flame.Melts and burn with black smokeSweet chemical odour
Continues to burn and melt.Forms small hard beads in cream and later tan colour
AcetateMelts and pulls away from the flame.Melts and burn with yellow flameAcrid, harsh, sharp odor.
Continues to burn and melt.Forms small beads
NylonMelts and pulls away from the flame.Melts ; bubbles as it burnsAcrid, harsh, sharp odor.
Continues to burn and melt.Forms small beads
.

There are some very important things to keep in mind 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

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

The air permeability of fabrics

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

Light blocking effect of curtain fabrics

Thickness of fabrics

Bond strength of bonded fabrics

Stretch properties of fabrics woven from stretch yarns

Abrasion resistance of textile fabrics 

Standard specification for knitted 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

Identification of finishes in fabrics

Insect pest deterrents on fabrics

Electrostatic clinging of fabrics

Colour measurement of textiles

Antifungal and Antibacterial finishes in textiles

Oil repellency 

Water repellency and resistance

Weather resistance 

Evaluation of wetting agents

Wrinkle recovery  of fabrics

Smoothness of seam 

The electrical resistivity of fabrics 

Read more at American Society for Testing Materials, Annual Book of ASTM Standards published yearly by the ASTM, Philadelphia, PA.

Comments 2

    1. Post
      Author

Leave a Reply

Your email address will not be published. Required fields are marked *