Course Code: Tex – 423

Course Title: Textile Testing & Quality Management-III

Course Credit: 3

IDENTIFICATION OF TEXTILE FIBERS

A number of methods are available for characterization of the structural, physical, and chemical
properties of fibers. Various methods are used for fiber identification like microscopic methods,
solubility, heating and burning method, density and staining etc. End-use property
characterization methods often involve use of laboratory techniques which are adapted to
simulate actual conditions of average wear on the textile or that can predict performance in end-
use.

TYPES OF TEST

1. The Non technical Test

• FEELING TEST

• BURNING TEST

2. The Technical Test

• MICROSCOPIC TEST

• CHEMICAL TEST

TESTS FOR IDENTIFICATION

REQUIREMENTS FOR TESTS

Preparation of test specimen

Apparatus for microscopic examination

Reagents used for chemical tests

Other tools and equipment

THE NON-TECHNICAL TESTS

FEELING TEST

The feeling test requires perception if it is to be of any value.

Skilled perception is acquired only after handling many different fabrics over a period of
time.

Limitations of this test become apparent when examining and comparing fabrics of different
fiber content.

BURNING TEST

To recognize the composition of fabrics by the burning test ,the sample of fiber, yarn of fabric
should be moved slowly towards a small flame and the reaction to heat carefully observed .One
end of the sample should be put directly into flame to determine its burning rate and
characteristics. The burning odor should be noted and the characteristics of the ash such as
amount ,form, hardness and color should be examined
 FIBER IDENTIFICATION BY BURNING TEST

IDENTIFICATION OF FIBRES THROUGH BURNING TEST

Cotton:

• When ignited it burns with a steady flame and smells like burning leaves. The ash lefties
easily crumbled. Small samples of burning cotton can be blown out as you would a candle.

Linen:

• Linen takes longer to ignite. The fabric closest to the ash is very brittle. Linen is easily
extinguished by blowing on it as you would a candle.

Silk:

• It is a protein fiber and usually burns readily, not necessarily with a steady flame, and smells
like burning hair. The ash is easily crumbled. Silk samples are not as easily extinguished as
cotton or linen.

Wool

• It is also a protein fiber but is harder to ignite than silk as the individual "hair" fibers are
shorter than silk and the weave of the fabrics is generally looser than with silk. The flame is
steady but more difficult to keep burning. The smell of burning wool is like burning hair.
MAN MADE FIBERS

Acetate:

• Acetate burns readily with a flickering flame that cannot be easily extinguished. The burning
cellulose drips and leaves a hard ash. The smell is similar to burning wood chips.

Acrylic:

• Acrylics burn readily due to the fiber content and the lofty, air filled pockets. A match
dropped on an acrylic blanket can ignite the fabric which will burn rapidly unless extinguished.
The ash is hard. The smell is acrid or harsh

• Nylon melts and then burns rapidly if the flame remains on the melted fiber. If i can keep the
flame on the melting nylon, it smells like burning plastic.
burns at the same time, the melting, burning ash can bond quickly to any surface it drips on
including skin. The smoke from polyester is black with a sweetish smell. The extinguished ash
is hard.

Rayon:

• It is a regenerated cellulose fiber which is almost pure cellulose. Rayon burns rapidly and
leaves only a slight ash. The burning smell is close to burning leaves

LIMITATION OF BURNING TEST

It is apparent that many fibers have similar burning reactions that might cause doubt and
occasional confusion.

TECHNICAL TESTS

formed for identifying various fibers. These tests require

high technology laboratory equipment and are much more reliable than the non technical fiber
tests.
 knowhow of handling chemicals
and their accurate analysis. These tests are very valuable for those fabrics that are a blend of
different yarns and also have certain special properties including flame retardancy etc.

TYPES OF TECHNICAL TEST

MICROSCOPIC TEST

microscope with a magnification of minimum 100 power.

as compared to man made ones.

makes it a little tough to distinguish the fibers even under a microscope

MICROSCOPIC TEST FOR NATURALFIBERS

• It is a single elongated cell. Under the microscope, it resembles a collapsed, spirally twisted
tube with a rough surface.

• The thin cell wall of the fiber has from 200 to 400convolutions per inch.
• Under the microscope, the hair like flax fiber shows several sided cylindrical filaments with
fine pointed ends.

• The fiber somewhat resembles a straight, smooth.

• Under the microscope , wool’s cross section shows three layers- epidermis, cortex and the
medulla.

SILK:

• It appears somewhat elliptical and triangular in cross section when we see under the
microscope.

• It is composed of fibroin, consisting of two filaments, called brin which is held together by
sericin.

MICROSCOPIC TEST FOR MANMADEFIBERS

YONS:

• Rayon fibers have a glasslike luster under the microscope and appear to have a uniform
diameter when viewed longitudinally.
• The cross sectional view has a bulbous or multi global appearance with indentations.

• These indentations appear as occasional markings.

• The basic microscopic appearance is generally fine ,round, smooth, and translucent.

• It is also produced in multilobal cross-sectional types.

POLYESTERS:

• Generally, polyester fibers are smooth and straight and the cross-section is round.

• This general characteristics may be altered to achieve certain characteristics.

•The methods of manufacturing of the acrylic fibers differ, the appearances vary accordingly.

•It has a bean-shaped cross section; its longitudinal appearance is straight and smooth.

•It has a flat, nut-shaped cross section.

•It has an almost round cross section.

• It is of two types verel mod acrylic and SEF mod acrylic.

SPANDEX:

• Spandex fibers are unique in appearance; they appear to be groups of fibers fused together.

GLASS:

•The fiber is smooth, round, translucent, highly lustrous, and quite flexible.

Asbestos fiber:

•This method is for the analysis of asbestos in air by Phase Contrast Microscopy. Results are
reported as fibers per cubic centimeter and depend on the volume of air sampled. PCM analysis
is not asbestos fiber specific and will count all fibers meeting the methods criteria for fiber
determination.

CHEMICAL TESTS

intended for the general consumers.

identity of the fibers used.

TYPES OF CHEMICAL TEST

Test:

• Also known as the Double Barrel Fiber Identification(DBFI), the test is based on the theory
that each fiber has its own distinct two- color reaction when treated with stain. A fiber will turn
to a particular color in the presence of dilute acetic acid and to some other specific color when
stained in the presence of a mild alkali.
 t Test:

• The test involves treating the fibers in certain solvents for identifying them. The technical test
is becoming difficult to conduct as most of the manufactured fibers and their blends are
chemically similar. There is no individual chemical or solvent test for separating or identifying
the fibers in combinations.

Distinguishing animal from vegetable fibers with an acid:

• As strong alkali destroy animal substances, a 5%of soda lye solution in water can be used to
eliminate wool and silk fibers from a sample that contains a mixture of fiber. The vegetable
fibers will not be affected by this solution.

Distinguishing vegetable from animal fibers with an acid

• As dilute acid destroy vegetable fibers, a 2%sulphuric acid solution can be used. A drop of
solution is placed on the sample, which is then pressed with a hot iron. The spotted area will
become charred if the sample is cotton linen or rayon.

NGUISHING SILK FROM WOOL:

• The use of concentrated cold hydrochloric acid will dissolve the silk and the wool fiber swells.

DISTINGUISHING NYLON FROM OTHER FIBRES:

• If the fabric is thought to contain nylon, the fabric may be immersed in a boiling solution of
sodium hydroxide. The nylon is insoluble in such a solution

OTHER FIBRES:

• Polyester is soluble in hot meta cresol; however ,unlike acetate it is not soluble in acetone, and
unlike nylon it is not soluble in concentrated formic acid.
 DISTINGUISHING ACRYLICS FROM OTHER FIBRES:

• Acrylic fibers will dissolve in 70 percent solution of ammonium thiocyanate at 130 degree
Celsius but the other fibers will not.

• Cotton and linen are immersed in a 1% solution of fuchsine in alcohol to give red rose color.
Later, they are washed and immersed into ammonia, linen retains the red coloration but cotton
does not.

DISTINGUISHING GLASS FIBERS FROM OTHER FIBRES:

• There are two specific solvents for quick identification of glass fibers, they are hydrofluoric
acid and hot phosphoric acid.

Advantages:
•More reliable than the non technical tests.

•Used for both manmade fibers and natural fibers.

•Easily conducted.

Limitations:
• Certain manufacturing and finishing processes like mercerizing, affects the appearance of the
fibers under the microscope.

•Very dark colored fabrics cannot be identified under microscope.

•Dye stuffs must be removed from fabrics.

Course Teacher:
MD. Fakhrul Abedin Himel
Lecturer,
Dept. of Textile Engineering,
Sonargaon University (SU)
Email: himel.fakhrul1991@gmail.com