This document discusses various methods for characterizing fibers, including microscopic, burning, and solubility tests. Microscopic tests allow distinguishing between natural and man-made fibers by examining fiber characteristics like cross-sectional shape under high magnification. Burning tests identify fibers based on how they burn and the smell, flame, ash, and melting behaviors. Solubility tests use solvents to dissolve certain fibers but not others, helping to identify fiber composition. These methods help determine the structural, physical and chemical properties of fibers.

1. Submitted By: Zobia HamidTS1

2.  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 etc.

3.  Microscopic test is a technical test that involves identifying the fabric
with the help of a microscope with a magnification of minimum 100
power.
 The test can easily distinguish between fibers.
 The test identifies the natural fibers more easily as compared to man
made ones.
 Synthetic fibers are very similar in appearance and the increase in the
number of varieties, makes it a little tough to distinguish the fibers even
under a microscope.

5.  Longitudinal
 Mature flat and ribbon like with
convolutions, thick wall and
small lumen
 Immature very thin wall and large
lumen with few convolutions
 Dead very thin and almost
transparent
• Cross Sectional
• Kidney Shaped
• Elliptical
• Very thin like a strip
• Nearly round or circular

6.  Longitudinal
 Smooth and Bamboo like with
cross marking nodes, no
lengthwise striations, narrow
lumen
• Cross Sectional
• Sharp polygonal shape with
straight sides. Immature oval
shape with large lumen

7.  Longitudinal
 Cylindrical , irregular, rough surface,
scale like structure, dark medulla may
appear on coarse wool fibres.
• Cross sectional
• Nearly round or circular
• It shows three layers- epidermis,
cortex and the medulla.

8.  Longitudinal
 Smooth surface, Structure less,
triangular shaped transparent
rod(Wild silk/Tussah silk - broader
fibre with fine, longitudinal lines
passing across filament)
• Cross sectional
• Triangular shape with rounded
corners(Tussah silk flat wedge or
spindle shaped

9.  Longitudinal
 Normal type fairly dense
longitudinal striations or fine lines
 Special type-may be smooth and
Structure less
• Cross sectional
•Irregular with serrated outline
•Oval or round
Polyester
• Longitudinal
• Structure less, uniform
diameter, rod like appearance
• Cross sectional
• Generally, polyester fibers are
smooth and straight and the
cross-section is round

10.  Longitudinal
 Smooth surface, uniform
diameter, rod like appearance
, some types with irregularly
spaced striations
• Cross sectional
• Rounded or Dumbbell shaped
• Longitudinal
• Uniform in width with a few
distinct longitudinal striations
• Cross sectional
• Irregular with serrated outline

11.  Burn test is the most accepted method for identifying the true nature of
any fabric.This test is carried out to know whether a fabric is made up of
a natural fiber, man made fiber, or a blend of natural and man made
fibers.

13.  Cotton :
 It is a cellulose fiber. It burns and
may flare up when lit.When ignited
it burns with a steady flame and
smells like burning leaves.
 Small samples of burning cotton can
be blown out as you would a candle.
No melted bead is left by it. After
burning, it continues to glow.
 It gives out smell like that of a
burning paper.
The smoke is gray or white.
The ash is fine, soft that can be
easily crumbled.
 Linen:
 A cellulose fiber, it 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.

14.  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. It sizzles and curls
away from flame and may curl back onto
fingernail.
 It leaves beads that are brittle, dark, and
easily crushed. It is self-extinguishing and
leaves harsh ash from crushed bead.
 Silk:
 It is a protein fiber and usually burns
readily, not necessarily with a steady
flame
 The ash is easily crumbled.
 Silk samples are not as easily
extinguished as cotton or linen.
 It leaves dark bead which can be easily
crushed.
 It leaves ash that is dark, gritty, fine
powder.
 It smells like burned hair or charred meat.
It gives out a little or no smoke and the
fume has no hazard.

15.  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
 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.

16.  Polyester: Polyester melts and
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.
 Nylon: Nylon melts and then
burns rapidly if the flame
remains on the melted fiber.
 If we keep the flame on the
melting nylon, it smells like
burning plastic

17.  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.

18.  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.

20.  Distinguishing vegetable from animal fibers with an acid : As dilute acid destroy
vegetable fibers, a 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
 Distinguishing animal from vegetable fibers with an acid : As strong alkali destroy
animal substances, a 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 Nylon from other fibers: 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
 Distinguishing Silk from Wool :The use of concentrated cold hydrochloric acid will
dissolve the silk and the wool fiber swells.

21.  DISTINGUISHING POLYESTERS FROMOTHER FIBRES: Polyester is
soluble in hot meta cresol
 DISTINGUISHINGACRYLICS FROMOTHER FIBRES: Acrylic fibers will
dissolve in 70 percent solution of ammonium thiocyanate at 130 degree
Celsius but the other fibers will not
 DISTINGUISHING SILK FROMWOOL: The use of concentrated cold
hydrochloric acid will dissolve the silk and the wool fiber swells.
 DISTINGUISHINGACRYLICS FROMOTHER FIBRES: Acrylic fibers will
dissolve in 70 percent solution of ammonium thiocyanate at 130 degree
Celsius but the other fibers will not
 DISTINGUISHING POLYESTERS FROMOTHER FIBRES: Polyester is
soluble in hot meta cresol