Dyes and Textile Dyes and Textile Dyes Dyes and Textile

Course Title:
Textile and Dyes
Credit hours:
1 Credit Unit
Pre Requisite:
Supplemental Material:
Lecture Notes and
Associated References

Aim and objectives:
The aim of this course is:
1- To introduce students to the relation between structure and
color of different types of dyes and their application on textiles.
2- To give an overview on:
a) Structure, synthesis and applications of some dyes.
b) Structure, the role of dying, spinning and finishing of fibers.
3- To help students have a knowledge about the natural fibers and
man-made fibers and also know how they can differentiate
between them.
Learning outcomes.
After finishing this course student should have the knowledge and
experience that is necessary to join any dyes textile working facility.

Recommended Textbook:
1- Introductory Textile Science, Marjory L. Joseph, California
State University, Northridge.
2- Color Chemistry, H. Zollinger 2nd ed. 1991.
3- Organic Chemistry in Color, P.F.Goren & P.Gregory 1983.
4- Chemical Principles of Synthetic Fiber Dying, S. M. Burbinshaw.
Blackbic Academic Professional (1992).

 Every person comes in contact with various textile
products each day.
 Most of us must make decisions at some point
concerning the selection of textile items.
 This process can be relatively easy if one has
knowledge about the appearance, maintenance,
durability, and comfort of textile products and the
factors involved in making these decisions. However,
as new developments occur in the field of textile
science and technology, it becomes increasingly
difficult to make intelligent selections because of the
amount of information that must be processed.

 Knowledge of the chemical, physical, and microbiological
properties of fibers and of the behavior that results from
techniques used in creating fabrics guides the consumer in
making wise selections in the marketplace.
 An attempt is made to provide key ideas and facts that help the
student and/or the consumer become adequately informed
concerning the selection, use, and care of textile products.
 Knowledge of proper maintenance procedures for the myriad
textile products helps ensure continued satisfaction with a
product after purchase.
 Attempts to provide key ideas and information that will aid
readers in their efforts to become well informed consumers.

 Textile science covers a large area. To begin with, the
word textile comes from the Latin textiles, "woven,"
which in turn comes from the Latin verb textere, "to
weave."
 In textile science, however, a textile is freely defined
as any product made from fibers; thus, the term refers
not only to woven fabrics, but also to nonwoven
fabrics, knitted fabrics, and special fabric
constructions.
 The term textile fiber refers to any product capable of
being woven or otherwise made into fabrics.
 These broad reciprocal definitions are now accepted
and used by nearly everyone who works with fibers
or fabrics at any step of manufacturing or processing.

 Textile fibers and the fabrics made from them have almost
limitless uses, and new applications are constantly being
found.
 The uses of fibers in clothing, home furnishings, and other
household textiles are familiar to everyone. But fibers are also
used in the building trades, as insulation in appliances, and by
industry for such products as filter clothes, pulley belts, and
protective apparel; they are used in all forms of transportation
including space vehicles; they are used in geoapplications to
provide for such factors as drainage and stabilization.
 In fact, fibers and textile products play their essential roles in
nearly every activity and situation conceivable from playing in
the sand to walking on the moon.

REASONS FOR STUDYING
TEXTILES
 A study of textiles will show, for example, why
certain fabrics are more durable and therefore more
serviceable for specific purposes. It will explain why
certain fabrics make cool wearing apparel as well as
give an impression of coolness when used as
decoration.
 The matter of cleanliness and maintenance must also
be estimated before purchasing, when that is an
important factor.

 Complete knowledge of textiles will facilitate an
intelligent appraisal of standards and brands of
merchandise and will develop the ability to
distinguish quality in fabrics and, in turn, to
appreciate the proper uses for the different qualities.
 As a result, both the consumer, merchant and
consumer customer will know how to buy and what
to buy, and salespeople will know how to render good
service to those consumers who have not had the
advantage of a formal course in textiles.
 Great strides have been made in the textile industry,
and have markedly influenced our general economic
growth.

 The prosperity and growth of related industries, such as
petroleum and chemistry, and dependent industries, such
as retail apparel stores, have produced broader
employment opportunities. Competition for the
consumer's dollar has fostered the creation of new textile
fibers with specific qualities to compete with well-
established fibers.
 New fiber blends have been created to combine many of
these qualities into new types of yarns with new
trademarks.
 There are also new names for the fabrics made of these
new fibers and yarns. New finishes have been developed
to add new and interesting characteristics to fibers,
yarns, and fabrics.

This welter of creativity and the myriad of
trademarks present a challenge to the
consumer, who is sometimes knowledgeable
but frequently confused. Yet one need not be.
Without being overly technical, this
information can be easily understood and
consequently very useful to the consumer in
business and personal life.
 All of this information can be adopted for
such utilitarian benefits as economy, durability,
serviceability, and comfort, as well as for such
aesthetic values as hand (or fee;), texture,
design, and color.

In the study of textiles, the students initial
interest will become an absorbing interest
when they discover the natural fascination of
fabrics and their cultural associations,
particularly when factual study is
supplemented by actual handling of the textile
materials.
The subject will seem worthwhile as they
become familiar with illustrative specimens
and fabrics and begin to handle and learn to
compare the raw materials of which fabrics are
made as well as the finished consumers' goods.

Classification of commen textile
fibers
 System of classification have been in use for
hundreds, perhaps thousands of years.
 Human beings, as scientists, learned in the early
stages of scientific development that placing like
items together facilited understanding.
 The system of chassificcation used in this text
provides for the division of fibers into two major
types: natural and man-made or manufactured.

 Natural fiber that occurs in nature can be classified as
vegetable, animal, and mineral.
 Vegetable fibers, found in the cell walls of plants, are
cellulosic in composition.
 Animal fibers, produced by animals or insects, are protein in
composition.
 The mineral fiber, asbestos is mined from certain types of
rocks.
 The use of the terms animal, vegetable and mineral in fiber
classification has been challenged because there are difference
between the behavior of vegetable cellulose used in man-made
cellulosic fibers and vegetable protein used in some of the
man-made protein fibers.

 The latter are comparable to animal fibers rather than
other vegetable fibers. Thus, a division of natural
fibers into cellulosic, protein and mineral type is
preffered because this system does related to the
chemical behavior of the fiber.
 Man-made fibers are derived from various sources.
 For instance, the natural material of cellulose has
been taken from cotton linters and wood pulp,
processed chemically, and changed in form and
several other characteristics into fibers of different
lengths, these are classified as man made cellulosic
fibers.

 The latter are comparable to animal fibers rather than
other vegetable fibers. Thus, a division of natural
fibers into cellulosic, protein and mineral type is
preffered because this system does related to the
chemical behavior of the fiber.
 Man-made fibers are derived from various sources.
For instance, the natural material of cellulose has
been taken from cotton linters and wood pulp,
processed chemically, and changed in form and
several other characteristics into fibers of different
lengths, these are classified as man made cellulosic
fibers.

 Noncellulosic polymer fibers are another group of
man made fibers.
 These synthetics have been and are still being created
by researeh chemists as companies strive to imitate
properties of other fiber, to develop other
characteristics, or to combine certain properties.
 These fibers are synthesized by combining carbon,
oxygen, hydrogen, and other simple chemical
elements into large, complex molecular combinations
or stracture called polymers. Chemists, in fact
discover new chemical compositions and invent new
substance that they form into fibers having certain
desired characteristies.

 The protein from such products as corn and milk has
been processed chemically and converted into man-
made protein fibers.
 Man made fibers created from other sources are
mineral fibers, metallic fibers and rubber fibers.
Mineral fibers, such as glass fibers are produced by
combining silica sand, limestons, and certain other
minerals.
 Metallic fibers are produced by mining and refining
such metals are aluminum, sliver and gold.
 The classification of fibers are summarized in table1.

Source or composition
Name of fiber
Type
Cotton boll (cellulose)
Flax stalk (cellulose)
Jute stalk (cellulose)
Hemp or abaca stalk (cellulose)
Agave leaf (cellulose)
Kapok tree (cellulose)
Rhea or China grass (cellulose)
Coconut husk (cellulose)
Pineapple leaf (cellulose)
Cotton
Linen
Jute
Hemp
Sisal
Kapok
Ramie
Coir
Pina
Natural Fibers:
Vegetable
Sheep (protein)
Silkworm (protein)
Hair-bearing animals (protein)
Wool
Silk
Hai
Animal
Table 1: Classification of fibers

Varieties of rock (silicate of
magnesium and calcium)
Asbestos
Mineral
Man-made Fibers
Cotton linters or wood
Cotton linters or wood
Cotton linters or wood cellulose
acetate
Rayon
Acetate
Triacetate
Cellulosic
Polymers
Corn, soybean, etc.
Natural or synthetic rubber
Aluminum, silver, gold, stainless
steel
Silica sand, limestone, other
minerals
Alumina, silica
Carbon
Azion*
Rubber Metal Glass
Ceramic
Graphit
Protein
Rubber
Metallic
Mineral

Aliphatic polyamide
Aromatic polyamide
Dihydric alcohol and terphthalic acid
Acrylonitrile (at least 85%)
Acrylonitrile (35-84%)
Polyurethane (at least 85%)
Ethylene or propylene (at least 85%)
Vinyl chloride (at least 85%)
Vinylidene chloride (at least 80%)
Phenol based novalac
Carbonic acid (polyester derivative)
Tetraminobiphenyl and diphenyl
isophthalate
Calcium alginate
Tetrafluoroethylene
Molecular graft of polymers
Mixture of polymers .
Monohydric alcohol and acrylic acid
Acrylonitrile (10-50%) and a diene
Vinylidene dinitrile (at least 85%)
Vinyl alcohol (at least 50%)
Nylon
Aramid
Polyester
Acrylic
Modacrylic
Spandex
Olefin
Vinyon
Saran
Novoloid
Polycarbonate
Polybenzimidazole
Alginate
Fluorocarbon
Graft
Matrix
Anidex*
Lastrile*
Nytril*
Vinal*
Noncellulosic
Polymers
* Not Presently commercially available

FIBER PROPERTIES
 A serviceable fabric is one which is properly designed for an
intended use. This intended use is spoken of as the "end-use."
The end-use of a fabric may be a beautiful party dress, a long-
wearing pair of overalls, a soft warm blanket, or a house dress
that dont shrink.
 To make such a fabric the manufacturer chooses fibers, yarns,
weaves, and finishes with a combination of properties which
will give the type of serviceability the consumer wants.
 The consumer, needs a knowledge and understanding of these
properties so can successfully select, use, and care for the
article buys.

Physical Properties of Fiber
I- Physical Properties Related to Hand and
Appearance
The physical structure of a fiber includes
length, diameter, surface contour, crimp, and
shape.
 These properties help to determine the
roughness, smoothness, softness, and soil-
resistance of a fabric.

Table 2: Comparison of fiber
physical structure
Cross section Diameter
in Microns
Length in inch Surface Contour
Cotton
16 to 20 ½ to 2.15 Convoulation
Flax
12 to 16 12-20 Smooth
Wool
18 to 40 2 to 16 Scales, crimp
Silk
11 to 12 Filament or
Staple
Smooth
Cuprammonium
Varies
with denier
" Smooth or
crimped
Viscose
" " "

Table 2 (Continued)
Acetate
" " "
Nylon
" " "
Orlon
" " "
Dacron
" " "
Dynel
" Staple only Crimped
Acrilan
X-51

1- Crimp refers to the waves or bends that
occur along the length of a fiber.
Wool has natural crimp. Manufactured fibers
may be given a permanent crimp. Fiber crimp
increases cohesiveness, resiliency, and
resistance to abrasion. It helps fabrics maintain
their "loft" or thickness.
(Fiber crimp should not be confused with yarn
crimp which results from the interlacing of
yarns in a fabric.)

2- Luster is the sheen, shine, or brightness of fiber
caused by reflection of light. Smooth fibers reflect
more light than rough or serrated fibers; round fibers
reflect more light than flat fibers.
Filaments which are laid together with little or no
twist reflect more light than short fibers which must
be twisted together to form yarns.
Manufactured fibers can be delustered by adding oil
or pigments to the solution from which the fiber is
spun.

3- Density and specific gravity are measures of the
weight of a fiber. Density is the weight in grams per
cubic centimeter (c. c.).
Specific gravity is the ratio of the mass of the fiber to
the mass of an equal volume of water at 4°C.
The weight of a fabric is determined by the density or
specific gravity of the fibers in it. For example: Orlon
is lighter in weight than wool. Thus an Orlon fabric
will weigh less than a wool fabric of the same
thickness.

DENSITY OF FIBERS
(Grams per c.c.)
Table 3
1.28
1.25
1.26
1.20
1.17
1.17
1.14
Dynel
Acetate
Vicara
Acrilan
Orlon
X-51
Nylon
2.56
1.52
1.48
1.50
1.38
1.30
1.30
Glass
Viscose
Cotton
Flax
Dacron
Wool
Silk

II- Physical Properties Related to
Durability
1- Strength of a fiber is the ability to resist strains and
stresses. It is expressed as tensile strength which is
measured in pounds per square inch (p.s.i.) or as
tenacity which is measured in grams per denier*.
 Some fibers gain strength when wet, some lose
strength, and some are unaffected by water. The
figures in the following chart are averages and would
vary with the denier of the fiber or the variety of
natural fiber. No high-tenacity fibers are included.
*Denier: Weight unit equals to 0.05 gm indicating fiber thickness
Denier scale defines the weight of 9000 meters of filament fibers
and then divided by 0.05 gm to give a number known as fiber
Denier. It is not used in spinned fibers.

FIBER STRENGTH
Table 4: (Tenacity grams per denier*)
Dry Wet
High Strength
Ramie
Flax
Glass
Nylon
Dacron
Medium Strength
Silk
Orlon
Cotton
X-51
Dynel
Acrilan
Low Strength
Viscose .
Cuprammonium
Acetate
Wool
6.7
6.6
6.4
5.8
4.8
4.5
4.5
3.8
3.6
3.0
2.5
2.0
2.0
1.5
1.3
8.7
8.4
5.8
5.4
4.8
3.9
4.4
4.8
3.0
3.0
2.0
1.0
1.0
0.8
0.8
* Figures are average for varieties and deniers.

2- Abrasion resistance is the ability of a fiber to
withstand the rubbing or abrasion it gets in
everyday use. Inherent toughness, natural
pliability, and smooth filament surface are
fiber characteristics that contribute to abrasion
resistance.
3- Cohesiveitess is the ability of fibers to cling
together in spinning process. This is important,
in staple fibers, but unimportant in filament
fibers.

4- Pliability or flexibility is the ease of bending or,
shaping. Pliable fibers are easily twisted to make
yarns. They make fabrics that resist splitting when
folded or creased many times in the same place.
5- Stiffness or rigidity is the opposite of flexibility. It is
the resistance to bending or creasing. Rigidity and
weight together make up the body of a fabric.
6- Elasticity means the ability of a stretched material to
return immediately to its original size.

7- Resiliency is the ability of a fiber or fabric to recover,
over a period of time, from deformation such as
stretching, compressing, bending or twisting. A
resilient fabric has good crease recovery, hence
requires a minimum of ironing. Resilient fabrics also
retain high bulk and do not pack down in use.
8- Loft is a term used in relation to compressional
resiliency. When pressure is put on a fabric, if it
springs back to its original thickness it is maintaining
its loft.

III- Physical Properties Related to Stability,
Care, and Comfort
1- Stability is the retention of size, shape, or form. A stable
fabric does not stretch, sag, shrink, beyond stated limits
with moisture, heat, or strains*.
2- Absorbency is the ability of a fiber to take up moisture and is
expressed as percentage of moisture regain, which is the
percentage of moisture that a bone-dry fiber will absorb
from the air under standard conditions of temperature and
humidity.
*Treatment with alkali and chlorine may be used to make wool shrink-
resistant, and chemicals that under ordinary conditions might be
harmful can be used under scientifically controlled conditions to
produce designs and beneficial finishes

 The moisture regain of a fiber can be changed.
Notice in the table that mercerizing increases cotton's
absorptive powers and acetylation lowers it.
(These processes are discussed later)
Mercerized cotton dyes more easily than
unmercerized cotton, and acetylated cotton is
more resistant to rotting, mildew, and
microorganisms than regular cotton.

Table 5: MOISTURE REGAIN
Fiber Percent of Moisture
Regain
Wool
Cuprammonium
Viscose
Mercerized cotton
Silk
Flax
Cotton
Acetate
Acetylated cotton
Nylon
Orlon
Acrilan
Dacron
Saran
Dynel
15-30
15
14
11
10
12
8
6
4
4
3
1.2
0.4
0
0

The ability of a fiber to absorb moisture is
directly related to washability, dyeing,
shrinkage, absorption of aqueous finishes,
comfort on humid days, and soiling.
Staple fibers hold more water than filament
fibers since they pack less compactly and
create a sponge-like condition in the yarn and
fabric. For this reason staple fiber fabrics
require a longer drying time.

3- Wicking or wetting refers to the conduction of
moisture along the fiber or through the fabric,
although the fiber itself does not absorb much
moisture. This property is related to surface
wetting and is not the same as absorbency.
4- Plasticity is that property of a fiber which
enables the user to shape it semi-permanently
or permanently by moisture, heat, and pressure
or by heat and pressure alone.

5- Electrical conductivity is related to the build-up of
static electricity charges on a fabric A good conductor
does not build up static charges.
6- Resistance to moths, mildew, and silver fish is due
to the chemical composition of the fiber. These
properties are important to the consumer because they
indicate the type of care needed during storage as
well as during use. Fibers without natural resistance
must have protective finishes added or have their
chemical composition changed to make them
resistant.

7- Flammability or inflammability refers to the
ease of ignition and the speed and length of
burning. Non-flammable fibers will not burn.
Flamniability depends not only on the
chemical composition but on the air
incorporated in the yarn or fabric.
Combustible finishes or dyes may make a non-
flammable fiber burn. Finishes can also be
added to make fibers non-flammable.

TERMINOLOGY AND GENERAL
INFORMATION
To be spinnable, a fiber must have sufficient
length, pliability, strength, and cohesiveness to
form a yarn. Milkweed and kapok are
examples of fibers that are too brittle to spin
into yarns; but they are usable for padding
material.
Fibers must also be inexpensive, available, and
constant in supply to be economically suitable
for production.

There are two classes of Fibers according to
length; (a) filament, and (b) staple.
a)Filaments are of a continuous length
measurable in yards or meters. The only
filament fiber that occurs naturally is silk. All
other filament fibers are man-made. Yarns
made from filament fibers are of two types;
multifilament and monofilament.

 Multifilaments yarns (Fig. 1A) are made of a number
of tiny filaments twisted together. The size and
number of the filaments can vary. Yarns of this type
give pleasant surface texture, softness, luster, and
luxurious drape. They are used in blouses, lingerie,
and silk- type dresses.
 Monofilament, (Fig. 1B) yarns are composed of a
single, solid strand of great strength and smoothness.
Very sheer hosiery is made from very fine
monofilaments. Sheer blouses, veils, and gowns are
other examples of monofilament use. Large
monofilaments are used in car seat-covers,
screenings, webbing for furniture, and similar
materials.

Fig. 1 Types of nylon fiber. A, Multifilament yarn.
B, Monofilament yarn. (Courtesy Du Pont
Company.)

(b) Staple fibers are short in length, measured in
inches, and range from three-quarters of an inch to 18
inches in length. Note Figure 2 showing staple fibers.
 The meaning of the word "staple" has changed
through the centuries.
 It was first used in the 14th Century as a descriptive
term for merchandise to which certain towns had
exclusive rights.
 Later it came to mean basic commodities in a
particular line of business, Still later, it was used to
express the length of wool and cotton fibers.

 During World War I, Germany began the practice of
cutting "artificial silk" into short lengths for use in
cotton- and wool-type fabrics; since there was a
shortage of these fibers.
 The word "staple" was applied to these cut fibers, and
is now a standard term for any fiber of a length
expressed in inches.
 All the natural fibers, except silk, are staple fibers.
Any filament fiber can be cut into staple of a length
determined by the end-use desired.

Fig. 2: Staple from man-made fibers after the uniformly
cut lengths have been fluffed. (Courtesy Du Pont
Company)

Man-made fibers are spun out through very
fine holes in a spinnerette. Man-made filament
and staple are not spun on the same equipment.
To make staple fiber, several thousand
filaments are spun out of one spinnerette in a
long rope like strand called tow. (See Fig. 3)
Figure 4 shows the various lengths into which
staple fiber can be cut. However, to make
filament yarns, only enough fibers are spun out
by one spinnerette to make the size of yarn
desired. Figure 4 shows the spinning of a
multifilament nylon yarn.

Fig. 3: A section of filament tow or rope showing
the types of filaments from which it is made
(Courtesy Du Pont Company).

Fig. 4: Filament rope or tow cut into uniform
lengths as by the ultimate use in fabrics and
garments(Courtesy Du Pont Company)..

 Three spinning processes, as shown below, are used
to produce man-made fibers.
 Stretching or drawing, heat-setting, and crimping are
after-treatments that can be used to control the size,
shape, and strength of the fiber.
 Crimping of staple fibers gives straight fibers a wool-
like waviness that makes them more cohesive, so that
they hold together better in the yarn. They also have
more bulk, loft, and resiliency.

 Filament tow may be crimped by running the fibers
through fluted rollers or by putting very high twist in
the wet tow and allowing it to dry. The crimp is set by
steam and the tow is then untwisted.
 In another crimping process the fiber is pushed into a
small crimping box by two wheels traveling at high
speed.
 This crowds the fiber into the box against a weight on
the top.This crowding causes the fiber to assume the
crimped shape. The box is heated and the fiber is set
in this shape.

* May also be wet spun
** Quenched in water bath.

Natural cellulosic Fibers
Cotton Ramie
Flax Jute
Hemp
 Plant fibers are composed of cellulose and therefore
are classified as natural cellulosic fibers. The term
natural cellulosic indicates the basic chemistry of the
fiber and provides a scientific method for comparing
natural cellulose with man-made Cellulosic fibers.
 Cellulose is a linear polymer or long chain molecule
built by combining several thousand anhydroglucose
units. Although glucose, a simple sugar, is soluble in
water, cellulose is not because of the immense size of
the polymolecule.

 Cellulose is a carbohydrate; it contains the elements carbon
(44.4 %), hydrogen (6.2 %), and oxygen (49.4 %). The
repeating molecular unit is diagramed in Figure( 5 ).
 Two glucose units combine first to form cellobiose; then many
cellubiose units combine to form cellulose.
 The number of anhydroglucose units in the cellulose molecule
is referred to as the degree of polymerization.
 Each repeating unit equals 1or 2 anhydroglucose units. These
units are (lipped over as they join together. Thus, in order to
diagram the method of joining, it is necessary to illustrate units
as in Figure 5.

C
C O
C
C
C
O
C
H
C C
C
O
C
H
OH
H
CH2OH
OH
H
CH2OH
H
OH H
H OH
O
C
H
H C O
C
C
C
O
C
H
C C
C
O
C
OH
H
H
OH
H
CH2OH
OH
H
OH
H
H
OH
H
CH2OH
H H
repeating unit
2 glucose units
A B C
n
Fig. 5: Cellulose Molecule
A= nonreducing end
B= cellobiose unit
C= reducing end
All of the cellulose fibers have some properties in common, and
each cellulose fiber has some properties that are different from
the properties common to the group.

Table 6 : PROPERTIES COMMON TO
ALL CELLULOSE FIBERS
Property Importance to the Consumer
High density
Low resiliency
Laks loft. Packs well
into compact yarns
Absorbency
Good conductor of
heat
Fabrics feel heavier than comparable
fabrics of other fiber content.
Fabrics wrinkle badly unless finished for
recovery.
Yarns can be creped. Tight, high-count
fabrics can be made. Makes close wind-
repellent fabrics.
Comfortable for summer wear. Good for
towels, diapers, and handkerchiefs.
Fabrics are cool for summer wear.

Table 6 (Continued)
Can withstand high
temperature
Not greatly harmed
by alkali
Harmed by mineral
Acids, little
affected by
organic acids
Resistant to moths
Attacked by mildew
Inflammability
Identification
Fabrics can be boiled to sterilize. No special
precautions in ironing needed.
Fabrics can be mercerized, bleached, washed with
strong soaps or detergents, and are not greatly
damaged by perspiration.
Fruit stains should be removed immediately from
a garment to prevent setting.
Storage problem is simplified.
Soiled garments should not be put away damp.
Filmy or loosely-constructed garments should not
be worn near an open flame.
Cellulose fibers ignite quickly, burn freely, have
an afterglow, gray feathery ash and burning paper
odor

Cotton
 Low Cost Launderability
 Low Resiliency Absorbency
 Cotton is the most widely used textile Fiber. This has
not always been true, however. Prior to the industrial
revolution wool and linen were the most widely used
fibers.
 In ancient times cotton was used in all Eastern
countries, India being the center of the cotton
industry from 1500 B.C. to 1500 A.D. As trade flowed
from the East into Europe, cotton fabrics became a
valuable commodity.

 In England, the textile industry began to develop
quite rapidly after 1500, with most of the advances in
spinning and weaving originating in that country.
England was interested, therefore, in importing cotton
fibers rather than fabrics.
 Production of cotton was encouraged in those North
American Colonies where the climate was mild. As
the production of cotton increased and improvements
in machinery made spinning of the short fibers easier
and quicker, the cost of cotton fabrics decreased.
 The low cost is perhaps one factor which led to the
wide use of cotton for textiles. Cotton does, however,
have a combination of desirable properties which
makes it suitable for many uses.

 Cotton is grown in all parts of the world where the
climate is mild.
 The most favorable conditions are in the cotton belt in
North America and in the Nile Valley in Egypt.
 The largest cotton growing areas are the United
States, India, China, the Soviet Union, Egypt, and
Brazil.
 The United States produces more cotton than the rest
of the world combined and is also the largest
consumer of cotton fabrics. India ranks second to the
United States as a producer and exporter of cotton.
Egypt ranks third as an exporter of cotton fiber, but
first in quality of fiber produced.

Growing, Harvesting, Ginning
 Cotton grows on bushes, three to four feet high. The blossom
appears, falls off, and the boll begins its growth. Inside the boll
are seeds from which the cotton fibers grow. Thus cotton is
classified as a seed-hair. When the boll is ripe it splits open and
the fluffy while cotton stands out like a powder puff (Fig. 6).
 The cotton is picked, either by hand or machine and sent to a
cotton gin where the seeds are removed and the fibers pressed
into 500-pound bales ready for-sale to the mills.
 The diagram shows a saw gin (Fig. 7) in which the whirling
saws pick up the cotton and carry it up to a knife-like comb
which blocks the seeds as the cotton is carried through.

Fig. 6. An opened cotton boll. (Courtesy
National Cotton Council of America.)

The seeds after ginning look like the buds on
the stem of a pussy willow. They are covered
with short fibers (¼ inch in length), called
linters.
These linters are removed mechanically and
are used for making rayon, acetate, film, and
lacquers.
The seeds are crushed to obtain cottonseed oil.

KINDS AND TYPES OF COTTON
 Different kinds and types of cotton are grown in
various parts of the world. Some of their basic
characteristics differ.
 Variations among cotton fibers also occur because of
growth conditions including such factors as soil,
climate, fertilizers, and pests.
 The quality of cotton fiber is based on its color
(degree of whiteness), length (or staple), fineness, and
strength. Usually, the longer fibers are finer and
stronger.

 The particular kind of cotton is often identified by the
name of the country or geographical area where it is
produced, and although a major portion of the world's
cotton is Upland type, it is still known by the place of
production whether Brazil, Zaire, Greece, Pakistan,
Russia, Syria, Turkey, Uganda, or San Joaquin Valley.
 The quality is associated with the name. The better
known kinds and types of cotton used in the United
States are Upland, American pima, Egyptian, and
Asiatic cotton.

Upland Cotton
 American Upland cotton constitutes over 99 percent of the
United States cotton crop and is used for many fabrics either
wholly or as a component of blends with man-made fibers.
The particular kind of Upland cotton from which these fabrics
are made is important because the quality and characteristics
vary among the kinds.
 Generally speaking. Upland cotton fibers are fairly white,
strong, and dull,and range in staple length from ⅞ to 1¼
inches (22- 32 mm).
 The Upland cottons are usually categorized as short-medium-,
and long-staple. The short-staple cottons are less than 1 inch
(25 mm) and are produced in Oklahoma and central and west
Texas. Lankart, GSA, Paymaster, and Tamcot are the principal
varieties.

 The medium-staple cottons are 1 to 1 inches (26-28
mm) in length and are produced in the Southeast, the
Mississippi Valley, and the low valleys of Arizona
and California. The principal varieties are Deltapine
and Stoneville.
 The long-staple cottons are 1⅛ inches (29 mm) or
longer and are grown in the high-altitude areas of the
Southwest. Acala is the primary variety.
 The cotton grown in the San Joaquin Valley of
California has a staple length from 1to 1inches (28-29
mm). The fiber is stronger than the other Upland
kinds.

American Pima
 American Pima cotton is grown in the upper Rio
Grande Valley of Texas, in New-Mexico, Arizona,
and southern California.
 The varieties Pima S-3 and Pima S-4, account for
most of the acreage. The staple length is from 1⅜
to1½ inches (35-38 mm) and the fiber is fine, strong,
lustrous, silky, and creamy-brown-white in color.
 American Pima fiber is used primarily for sewing
thread although a small amount is used in high-
quality broadcloth and other fabrics where silky
smoothness, softness, and luster are desired.

Egyptian
 Egyptian cotton is imported into the United States in
small quantities. Menoufi and Ciza 68 are the
varieties used to produce most of the exported crop.
 The fibers are light brown, fine, strong, and 1¼ to 1½
inches (32-38 mm) in length. They are used in the
same applications as American Pima. Giza 45 is
exported in limited quantities.
 The fiber is light brown, fine, strong, and 1⅜ to 1⅝
inches (35-41 mm) in length. It is used in applications
where fine yarns or strong yarns are required.

Asiatic
Asiatic cottons are produced in India, China,
and the Near East.
For the most part these are coarse fibers less
than 1 inch (25 mm) in length.
The major usage in the United States is in
surgical supplies.

Fiber Properties
Microscopic Properties
Cotton fibers are composed of an outer cuticle (skin) and a
primary wall, a secondary wall, and a central core. or lumen,
(Fig. 8), immature fibers exhibit thin wall structures and a
Fig. 8: Diagram of a cotton fiber, cross section.

 large lumen,whereas mature fibers have thick walls and a
small lumen that may not be continuous, because the wall
closes the lumen in some sections (Fig. 9 ). Fibers that have
been swollen, as in mercerization (Fig.10), do not show the
twist as clearly as do untreated fibers, and the cross section
tends to be smooth and round instead of flat and folded.
Immature fibers may have an appearance similar to mercerized
cotton.
 The longitudinal view of regular cotton (Fig. 9) shows a
ribbonlike shape with twist (convolutions) at irregular
intervals. The diameter of the fiber narrows at the tip. The
lumen may appear as a shaded area or as siriations; this is
more obvious in immature fibers. Some fibers are nearly
circular, some are elliptical, and some are kidney-shaped.
Immature fibers are generally more irregular than mature
fibers.

Fig. 9: Photomicrograph of cotton showing
longitudinal and cross-section views. (From Werner
Von Bergen and Walter Krauss, Textile Fiber Atlas.
Copyright 1949 by Textile Book Publishers, Inc.)

Fig. 10: Photomicrograph of mercerized cotton
showing cross-section and longitudinal views.
(From Werner Von Bergen and Walter Krauss,
Textile Fiber Atlas. Copyright 1949 by Textile Book
Publishers. Inc.)

PROPERTIES
SHAPE AND APPEARANCE
Cotton Fibers are fairly uniform in width, which
varies between 12 and 20 microns; the central portion
of the fiber is wider than either end.
Depending on variety and growing conditions, the
length of the cotton fiber used in fabric
manufacturing ranges from ½ inch to 2½ inches
(1.27-6.35 cm), with most fibers in the ⅞ to 1¼ inch
(2.22-3.18 cm) category.

Physical Properties
 Cotton fibers are quite strong because the long-chain cellulose
molecules have a high degree of orientation within the fiber.
However, much of the fiber strength is lost in the yarn because
under strain the fibers slip past one another instead of
breaking.
 Cotton's strength increases approximately 25 per cent when
wet. This is important in washing and ironing. Fabrics which
are stronger when wet can be handled with less care.
 The strength of cotton is improved by treating with caustic
soda. This process, called mercerization, also increases its
luster and affinity for dyes.

 The caustic soda does not combine chemically with
the fiber but causes a physical change in the
molecular structure of the fiber, which in turn
changes its physical appearance.
 The fiber swells, and some of the convolutions are
removed, making it almost: rod-like in cross section.
 The lumen becomes much smaller. See Figures 9&10
and for a comparison of mercerized and unmercerized
cotton.

 Cotton fibers do not have body, so cotton fabrics tend to be
rather limp and starching is a common practice.
 Durable resin finishes are also used to obtain a crisp effect.
However, firm fabrics (without a finish) are made from cotton
by using coarse yarns and packing them tightly into the cloth.
 Like all cellulose fibers, cotton is low in resiliency. Fabrics
wrinkle easily and the wrinkles do not shake out. Resin
finishes are used to counteract the wrinkling of cotton.
 Cotton is very absorbent because of the many available
hydroxyl groups. Cotton is our most washable fiber. It can
be boiled to sterilize it, ironed with a hot iron to remove
wrinkles, washed in strong soaps to remove soil, and bleached
to maintain a white color.

 Cotton for dresses has "come out of the kitchen" and
is being used for high style, around-the-clock, all-
season clothing. This use presents a problem in care.
Many women prefer to send an expensive cotton
dress to a dry cleaner who is skilled in finishing and
pressing garments.
 Dry cleaning does not remove soil satisfactorily.
Washing, even by a professional, is not very
satisfactory for tailored suits that have padding,
interlacings, and linings. Research is being done to
make dry cleaning suitable to cottons or cottons
suitable to dry cleaning.

Chemical Properties
 Cotton contains carbon, hydrogen, and oxygen. Its
cellulose content varies from 88 to 96 %. Scoured and
bleached cotton fabrics are approximately 99 %
cellulose .
 Bleaching of cotton is usually done with sodium
hypochlorite, which is harmful to cotton if too much
is used. The bleach is used to destroy coloring-matter;
but after the coloring-matter has been destroyed, the
bleach will oxidize the cotton, causing it to lose
strength.

 In commercial laundries and in factory bleaching, an
acid is used following bleaching to neutralize any
remaining alkali. At home, clothes should be
thoroughly rinsed with water after bleaching.
Hydrogen peroxide is the least harmful bleach to use
on cotton goods.
 Cotton is quite sensitive to the action of dilute
mineral acids but not very sensitive to organic acids.
However, mineral acids can be used under controlled
conditions for finishing cotton. For example, cold,
concentrated sulfuric acid is used to give a
permanently crisp, transparent organdy finish.
 Cotton is resistant to moths but is attacked by mildew
and silverfish. Mildew and mold occur under moist,
warm conditions.

 The micro-organisms need heat, moisture and food to
develop and grow. For this reason, cotton fabrics
should be stored unstarehed in a dry place and care
should be taken to see that soiled clothes are dry
before being put into the dirty clothes hamper.
 Cotton burns readily and ignites easily, leaving an
ash-like burned paper. The burning test does not
distinguish cotton from other cellulose fibers.
 Cotton fibers can be chemically changed to give them
new properties without changing their fibrous form.
These modifications are achieved by a chemical
reaction with the hydroxyl groups of cellulose.

1. Cyanoethylation . This is the newest modification of
the cotton fiber. Cotton fibers are treated with
acrylonitrile (the substance used to make Orlon and
Dynel). The process was developed primarily to make
a rot-resistant cotton.
The modified cotton is extremely rot-resistant and also
is stronger, more resistant to abrasion, and dyes more
deeply.
Fabrics retain the hand and appearance of cotton.
Yarns made of modified cotton are 30 to 35 per cent
stronger, and if mercerised are 50% stronger.
Cyanoethylated cotton will probably be important for
industrial uses, fish nets, and sandbag covers. (T-7 is
a trade name for cyanoethylatcd cotton.)

2. Acetylation . Cotton is treated with acetic
anhydride to give a partially acetylated cotton
which is resistant to mildew, heat, and rot.
This modified cotton has been used for laundry
press covers and pads which become charred
in a week's time when normal cotton is used.
The treated cotton covers have shown little
charring after six weeks' use.

3. Etherification. The etherification of cotton yarns
with monochloroacetic acid have produced yarns
which are soluble in water. These yarns can be used
in weaving sheer fabrics as the alginate yarns
produced in England are used.
4. Aminized cotton . This cotton is produced by
introducing amino groups into the fiber. This makes
possible the use of wool dyes on cotton. It also makes
possible the addition of certain organic substances for
water repellency and rot resistance. Treated fabrics
have a texture and appearance similar to wool. The
finish adds 10 to 15 cents per pound to the cost of the
fabric.

5- Affinity for Dyes. Cotton has a good affinity for
direct dyes, but oxidation, basic, azoic, and reactive
dyes may be also effectively used.
Colour fastness is generally good, but specific
conditions should be considered. Fastness of dye to
washing can be tested by washing a sample in hot
water.
Fastness to light can be tested by exposing a sample to
light for a week or more. Penetration or thoroughness
of dyes can be tested by raveling a yarn and
examining its unexposed surface.

BAST OR STEM FIBERS
Flax Jute
Ramie Hemp
 Bast fibers lie in bundles in the stalk of the plant just
under the outer covering or bark. They are sealed
together by a substance composed of pectins, waxes,
and gums. To loosen the fibers so they can be
removed from the stalk, the pectins must be dissolved
by bacterial retting and the woody portion of the stalk
must be broken away. Because the work involved in
processing these fibers has always been extremely
laborious, production has flourished where hand labor
is cheap. Mechanization has been slow and although a
great deal has been done, complete mechanization is
still to be achieved.

FLAX
 High Strength
 Low Resiliency
 Natural Body
 Historical Review
Flax is considered by many to be the oldest fiber used
in the Western world. Fragments of flax fabric (linen)
have been found in excavations at the prehistoric lake
regions of Switzerland, which date back to about
10,000 b.c.

The use of linen in Egypt between 3000 and
2500 b.c. has been verified. These early fabrics
were of a fineness that has never been
duplicated.
Examples have been found that were spun so
fine that more than 360 single threads joined
together formed one warp thread.
Oiler fabrics were made with more than 500
yarns per inch (197 yarns/cm).

Growth ond Production
 Flax is a bast fiber—a woody fiber obtained from the phloem of
plants. It derives from the stalk or stem of Linum usitalissimum.
 The flax plant, requires a temperate climate with generally cloudy
skies and adequate moisture. Bright sunlight and high
temperatures are damaging unless alternated with abundant
rainfall. Flaxseed is planted in April or May. When the crop is to
be used for fiber, the seed is sown close together so that the plants
will be closely packed and produce fine plants with long, thin
stems.
 The plants grow to a height of 3 to 4 feet (0.9-1.2 m) for fiber use.
The blossoms are a delicate pale blue, white, or pink. Flax for
fiber is pulled before the seeds are ripe.

Processing
Pulling and Rippling
Flax for fiber is pulled by hand in some countries or
by mechanical pullers.
It is important to keep the roots intact, as fibers
extend below the ground surface. Harvesting occurs
in late August when the plant is a rich brown color.
After drying, the plant is rippled: that is, it is pulled
through special threshing machines that remove the
seed bolls or pods.

Retting
 To obtain fibers from the stalk, the outer woody portion must
be rotted away. This process, known as retting, can be
accomplished by any of several procedures.
 Dew retting involves the spreading of the flax on the ground,
where it is exposed to the action of dew and sunlight. This
natural method of retting gives uneven results but provides the
strongest and most durable linen. It requires a period of 4 to 6
weeks.
 Pool retting is a process whereby the flax is packed in sheaves
and immersed in pools of stagnant water. Bacteria in the water
rot away the outer stalk covering. The time required is 2 to 4
weeks.

 Tank retting, similar to pool retting, utilizes large
tanks in which the flax is stacked. The tanks are filled
with warm water, which increases the speed of
bacterial action. Tank retting requires only a few
days. Both pool and tank retting give good-quality
flax that is uniform in strength and light in color.
 Chemical retting is accomplished by stacking the flax
in tanks, filling the tanks with water, and adding
chemicals such as sodium hydroxide, sodium;
carbonate, or dilute sulfuric acid. Chemical retting;
can be completed in a matter of hours instead of ,days
or weeks. However, it must be carefully controlled in
order to prevent damage to the fiber.

Breaking and Scutching
After the retting is complete, the flax is rinsed
and dried.
The stalks are then bundled together and
passed between fluted rollers that break the
outer woody covering into small particles.
It is then scutched to separate the outer
covering from the usable fiber.

Hackling
 After scutching, the flax fibers are hackled, or
combed. This operation separates the short fibers,
called tow, from the long fibers, called line. This is
accomplished by drawing the fibers between several
sets of pins, each successive set fine than the
preceding set. This process is similar to the carding
and combing operation used for cotton and prepares
the flax fibers for the final steps in yarn manufacture.
 As the fibers are removed from the hackling machine,
they are drawn out into a sliver.

Fig. 11: Retted flax. Left: Water or tank retted.
Right: Dew retted. (International Liner Promotion
Commission)

Spinning
The flax sliver is drawn out into yarn. and
twist imparted.
Flax fibers are spun either dry or wet, but wet
spinning is considered to give the best quality
yarn.
The final yarn processing is similar to that
used for cotton fiber.

Fiber Properties
Microscopic Properties
Flax fiber is composed of bundles or fibrils of fiber
cells held together by a bonding or gummy substance
(Fig.12). Under the microscope the longitudinal view
of the fiber shows the width to be quite irregular
(Fig.13). The central canal, or lumen casts a shadow,
giving a slightly darker effect down the center. There
are no convolutions as in cotton but longitudinal lines
or striations can be seen.
The points at which the fiber width changes are
marked by swellings and irregular joint formations
called nodes. These are similar to the joints in
bamboo.

The cross-sectional view of flax (Fig.13),
clearly shows the lumen, the thick outer wall,
and a somewhat polygonal shape.
Immature fibers may be oval in shape and have
larger lumen than mature fibers.

Physical Properties
Shape and Appearance
Flax fiber is not so fine as cotton: flax cells have an
average diameter of 15 to 18 microns and vary in
length from ¼ inch to 2½ inches (0.63-6.35 cm).
Bundles of cells form the actual fiber as it is used in
spinning into yarns, and these bundles may be
anywhere from 5 to 20 inches (12.7-50.8 cm) long.
Line fibers are usually more than 12 inches (30.5 cm)
long; tow fibers are shorter.
The natural color of flax varies from light to ivory to
gray. The choice fibers from Belgium are a pale
sandy color and require little or no bleaching.

Luster
 Flax fibers have a high natural luster with an
attractive sheen.
Schematic diagram of fiberls in flax
fibers.
Photomicrograph of flax. Longitudinal
view. (Dupont Company)

Fig. 13: Photomicrograph of flax.
Cross section. (Dupont Company)

Tenacity (Strength)
 Flax is a strong fiber; the normal tenacity ranges between 5.5 and
6.5 grams per denier. Some fiber of inferior quality may have a
tenacity as low as 2.6 g/d, and some top-quality fiber may exhibit
a tenacity as high as 7.7 g/d. Fabrics of flax are durable and easy
to maintain because of the fiber strength. When wet, the fiber is
about 20 percent stronger than when dry.
 Most linen fabrics for apparel use have been given various resin
finishes to provide consumers with easy-care performance. These
finishes reduce the strength of flax so that these fabrics tend to
give less durability.
 Flax has low pliability or flexibility, which may result in reduced
serviceability in uses where frequent bending is required.

Resiliency
Linen fabrics are prone to crease and
wrinkle badly. They are somewhat stiff and
possess little resiliency. However, finishes can
be applied that help offset this disadvantage to
some degree.
Density
The density of flax is 1.5 grams per cubic
centimeter and is comparable to that of other
cellulosic fibers.

Moisture Regain
Flax has a standard moisture regain of about 12
percent. The saturation regain is comparable to that of
other cellulosic fibers. Flax has outstanding wicking
properties, which makes it possible to move moisture
along the fibers and yarns as well as to absorb
moisture.
Dimensional Steblity
Flax fibers do not shrink or stretch to any marked
degree. However, as in the case of cotton, yarns and
fabrics are subject to some relaxation shrinkage
unless preshrunk during finishing operations. Ironing
linen fabrics while damp will help stretch them back
to their original size.

Thermal Properties
Like other cellulose fibers, flax burns quickly.
It is highly resistant to decomposition or
degradation by dry heat and will withstand
temperatures to 150°C (300°F) for long
periods with little or no change in properties.
Prolonged exposure above 150°C (300°F) will
result in gradual discoloration.
 Safe ironing temperatures may go as high as
260oC (500°F) as long as the fabric is not held
at that high temperature for any length of time.

Chemical Properties
 Flax is highly resistant to alkaline solutions; it is also
resistant to dilute acids, but concentrated acids and
hot dilute acids will cause deterioration. Flax has
excellent resistance to dry-cleaning solvents and other
organic compounds encountered in normal
maintenance.
 There is a gradual loss of strength when linen fabrics
are exposed to sunlight, but this is not serious.
Consequently, flax makes a good choice for curtain
and drapery fabrics. If stored properly, linen will age
remarkably well. Table coverings and sheets packed
away for many years have proved to be as strong as
new linen fabrics.

Biological Properties
Dry linen has excellent resistance to mildew,
but if the fabric is moist or stored in a humid
atmosphere, mildew will grow rapidly and
damage the fiber.
Flax has good resistance to most household
insects and pests; silverfish may damage the
fiber if it has been starched.

Finishes for Linen
 Few finishes are used on linen fabrics. Because linen
is low in resiliency, dress fabrics are treated with
resins to improve their crease recovery .
 Mercerizing improves the luster and crease recovery
of linen and is used to shrink linen. Compressivc
shrinking is also done on linen. It is not necessary to
preshrink linen when preparing it for use in home
sewing. While most of the imported dress linens are
not completely shrunk ,if they are ironed while they
are still quite damp, there will be no difficulty with
shrinkage.

 If linens are completely shrunk, there might be a
tendency for them to stretch or sag in wear.
 Mercerizing also increases dye affinity, and the fabric
will dye a more brilliant shade. Linen has less affinity
for dye than does cotton. Color fastness has been
greatly improved by use of better dyes and some of
the resin finishes.
 Most of the Irish linens are vat-dyed. Beetling is a
finish that is used only on linen or a few of the fabrics
made to resemble linen. As the cloth revolves slowly
over a huge wooden drum, it is pounded with wooden
block hammers. This pounding may continue for a
period of 30 to 60 hours.

 It flattens the yarns and makes the weave appear less
open than it really is.
 The increased surface area gives more luster, greater
absorbency, and smoothness to the fabric. Beetled
fabrics are softer than unheeded fabrics.
 The effects of beetling disappear some-what in
laundering and the space between the yarns increases.
Not all linen fabrics are beetled.
 Quality in linen is determined by the length and
fineness of the fiber, the character of the yarns, the
degree of bleach, and the fastness of the dye.

Care of Linen
 Although linen may be dry cleaned it should be
washed, since proper washing increases the beauty of
the fabric.
 Flax is a very smooth fiber that sheds dirt readily and
if washed before it becomes too soiled, requires no
bleaching.
 Drying while linen in the sun is a good way to keep it
white. If bleaches are necessary to remove stains, a
mild peroxide bleach is best and it should be
thoroughly rinsed out with water.

 Stareh is not necessary, since linen has a natural
stiffness that it retains throughout the life of the
fabric.
 Bluing may be used. However, bluing serves only as
a mask for yellowing and if proper washing is done,
no bluing should be necessary. Bluing should always
be completely removed from any linen that is to be
stored, as some bluing contains an iron solution that
will oxidize during storage and form rust spots. These
rust spots can be removed by a commercial rust
remover or by the home remedy of salt, lemon juice,
and sunshine.
 Linen fabrics which freeze while drying outdoors
should be allowed to thaw completely before
handling. Fibers break easily when in the frozen state.

 Linen should be ironed while damp, first on the
wrong side and then with a final ironing on the right
side until completely dry.
 Creases should not be pressed into the fabric and
folds should not always come at the same place. It is
best to roll linen fabrics on a cardboard cylinder for
storing.
 Mild scorch stains can be removed if placed in the
direct sunlight without wetting and if the fabric is
allowed to remain until the stain disappears.

Jute
Jute is a bast fiber like flax. The jute plant is
cultivated in a manner similar to that used for
flax, the seeds are planted close together and
grow to a hight of 14 to 20 feet (4.6 to 6.1 m).
The fiber are extracted from the stem by retting
followed by breaking and scotching. Properties
of jute fiber can be summarized in table (7).

Table (7) Properties of Jute
Fibers
Property Evaluation
Shape
Luster
Tenacity (strength)
Elastic recovery
Elongation
Resiliency
Density
Moisture absorption
Dimensional stability
Resistance to acids
alkalies
sunlight
microorganisms
insects
Thermal reactions
to heat
to flame
Irregular in diameter and length, 5 to 20 feet
long
Silky
3.5 g/d
Very low; 74% at 1% extension
1.7-1.9%
Low
1.5 g/ccm
13.7% at standard conditions
Good to dilute;
Poor to concentrated acids
Very good
Good
Good
Good
Similar to those of flax
Burns readily.

Care of jute is similar to that of linen except
for the fact that coloured jute may require dry
cleaning. Jute is difficult to dye with colorfast
properties.
HEMP
Hemp is a bast fabric that was probably used
first in Asia. Records indicate that it was
cultivated in China before 2300 b.c. Sometime
during the early Christian era, hemp was
carried into Europe and became an important
fiber.

 Today, hemp is grown on every continent and in
nearly every country.
 A tall herb of the mulberry family, it is a tough plant
and will grow at altitudes to 8000 feet (2440 m) and
in climates where temperatures are warm or hot. It
can be replanted in the same fields without depleting
soil nutrients.
 The plants are cut by hand and then processed in a
manner very much like that used for flax. It requires
retting, followed by stripping or scutching to obtain
the fiber. Hackling, drawing, and spinning follow.
The fiber is dark tan or brown and is difficult to
bleach; however, it can be dyed bright and dark colors
successfully.

Hemp fibers vary widely in length from 1 inch
to several inches. Fibers used for industrial
purposes may be several inches long, whereas
fibers used for domestic textiles are about 0.75
% inch to 1 inch (1.9- 2.54 cm) long. The
density of hemp is 1.45 grams per cubic
centimeter.
 Its strength varies between 5.8 and 6.8 grams
per denier. Elongation and elasticity are both
low . Standard moisture regain in 12 percent,
and it can absorb moisture up to 30 percent of
its weight.

 Hot concentrated alkalis will dissolve hemp, but hot
or cold dilute or cold concentrated alkalies will not
damage the fiber. With the exception of cold and
weak acids, minmeral acids will reduce the strength
and enentually destroy the fiber completely. Organic
solvents used in cleaning and bleaches, if handled
properly, will not damage hemp.
 The thermal properties and the effect of sunlight are
the same as for cotton. Hemp is resistant to insects
but is damaged by mildew.
 Hemp fibers are used for cordage, rope, sacking, and
heavy-duty covering fabrics. In some countries, hemp
has been made into fine fabrics for use as wall
coverings or draperies.

Natural Protein Fibers
Wool- Hair-Silk
Commonly used natural protein fibers are wool
and mohair.
Those less commonly used are the specially
wools (vicuna, llama, cashmere, guanaco,
alpaca, camel's hair) and silk.
Vicara and Caslen are man-made protein
fibers.

Table 8: PROPERTIES COMMON TO ALL
PROTEIN FIBERS
Property Importance to the Consumer
Medium density Fabrics of same thickness feel lighter than cellulose
fibers.
Weaker when wet Wool loses about 40% of its strength when wet; silk
15%, and Vicara 50%. Handle carefully during washing.
Resilient Wrinkles hang out between wearings. Fabrics tend to
hold their shape.
Poor conductors of electricity Fabrics build up static electricity in cold, dry weather,
especially if they are worn over nylon undergarments.
Hygroscopic Comfortable in cool, damp climates.
Harmed by oxidizing agents Chlorine bleaches damage fiber. Sunlight causes white
fabrics to turn yellowish. .
Weakened by alkalis Use neutral or slightly alkaline soap or detergent.
Perspiration weakens the fibers.
Harmed by dry heat Wool becomes harsh and brittle and scorches easily with
dry heat. Silk yellows with heat.
Do not support combustion Burn briefly.
Identification Protein fibers do not burn readily, are self-extinguishing,
have odor of burning hair, and form a black crushable
ash.

The protein fibers are made up of carbon,
hydrogen, oxygen, and nitrogen.
Protein fibers are more chemically reactive
than cellulose fibers because they have both
positive and negative reactive groups.
Wool contains sulfur in addition to the above
elements and this gives it some properties
which are different from silk and vicara.

WOOL
Warmth
Resiliency
Felting
Damaged by Moths, Alkalies
Historical Review

No one knows when man started using wool as
a textile fiber. Probably man first used the
skins for clothing and later discovered that be
could form a cloth of felt by pounding and
matting the fibers together.
We do know that man knew of wool during the
Second Stone Age and that as early as 3000
b.c. the Babylonians were experts in spinning
and weaving wool cloth.

 In the Dark Ages the wool industry, which had
become important in the world, almost disappeared.
In the 11th and 12th Centuries in Europe textile
industries began to reappear, and there was a big
demand for wool.
 The Spaniards developed the Merino sheep which has
the finest wool and is the Forerunner of breeds
producing fine wool today.
 The word "wool" is Found in all European tongues.
The Greeks called it "lenas"; the Romans called it
"lana ; the Gauls called it "laine"; the Germanic tribes
and Saxons of England named it "Woll" or "wolle."

 Most wool comes from the temperate zone of the
Southern Hemisphere, Australia, Argentina, New
Zealand, South Africa, and Uruguay.
 In the Northern Hemisphere, the United States, Great
Britain, Spain, France, and Italy are the leaders.
Australia produces one-fourth of the world's wool.
The United States produces about one-third as much
as Australia.
 The United States, however, is the largest consumer
of wool and the largest, producer of wool fabrics,
both in terms of yardges and dollar value.

Shearing
 Sheep are sheared once or twice a year, depending on
the locality, by traveling crews.
 An expert shearer can clip as many as 100 to 200
sheep a day. The fleece is kept in one piece with the
skirts and breach folded in , and the flesh side
outside.
 The fleece is tied with paper twine. One tier can keep
up with two shearers. The fleeces are packed tightly
into six-foot sacks. The fleeces are sometimes graded
before packing but usually are graded in the
warehouse before being sold.

Pulled Wool
Pulled wool is obtained from animals which
are sold for meat.
The pelts are washed and brushed and then
treated chemically to loosen the fibers.
 The yield of pulled wool is about one-fifth as
much as that of sheared wool.

Sorting
Sorting is the breaking up of an individual
fleece into various qualities.
The diagram (Fig. 14) shows how the fleece is
sorted.
The best quality fiber comes from the
sides andshoulders, the poorest quality fiber
from the lower legs. "the sorting of the fleece
is based on fineness.

Wool as it comes from the sheep and as it is
sold is called grease wool.
It contains impurities such as sand and dirt,
grease, and dried sweat called suint.
The grease, in various stages of purification, is
used for a wide variety of commercial
purposes such as medicines toilet preparations,
and softeners.

Fiber Properties
Molecular Structure
Wool is a protein substance called keratin and is
composed of 18 amino acid residues, of which 17 are
present in measurable amounts. The amino acid
residues join together, and the molecules are
arranged in such a manner as to give the fiber many
of its desirable properties, such as resiliency and
elasticity. The molecular structure frequently given
for wool is diagramed in Figure 15. This figure
shows the folded characteristic of the alpha keratin
molecule. When extended, it is referred to as beta
keratin.

 As soon as the tension used to form beta keratin is removed,
the molecule attempts to return to the alpha or folded form.
This is partly responsible for the ability of wool fiber to
recover its shape after distortion.
 Scientific analysis of wool completed during the middle of
20th century has provided evidence of a helical or spiral
structure rather than a folded form for keratin. Figure 15 is a
diagram of this helical structure.
 It is believed that the helical structure may be responsible for
the high elongation property of wool fibers. Furthermore,
additional researeh has suggested that the cystine linkage and
the intramolecular hydrogen bonding are responsible for the
shaping and setting characteristics of wool fibers and fabrics.

CO
RHC
NH
OC
CH-CH2-S-S-CH2
HN
CO
RHC
NH
OC CO
HN
CHR
OC
NH
CH
CO
HN
CHR
OC
RHC
NH
OC
CH-CH2-CHO
HN
CO
RHC
NH
OC
CH-CH2-COO-
HN
CO
RHC CHR
OC
NH
+
H3N-HC-HN-H2C-H2C-H2C-HC
CO
HN
CHR
OC
NH
+
H3N-H2C-H2C-H2C-H2C-HC
CO
HN
CHR
HN
Cystine Linkage
glutamic acid lysine
salt linkage
R = amino acid or other reactive groups
Fig. 15: Digram of the molecular structure of wool. (After Asbury)

Molecular Structure
Wool is a protein called keratin. Like all proteins it is
a complicated chemical compound made up of
various amino acids which are linked together to form
polypeptide chains cross-linked by cystine and salt
linkages. Thiscross-linking is largely responsible for
wool's resiliency.
The chain molecules of Keratin lie normally in wavy
lines. (These should not be confused with fiber
crimp.) Even uncrimped wool fibers have molecular
crimp. These chain molecules might be compared to
springs- when the fiber is stretched, the crimp
straightens out and the chains elongate; when the
strain is removed.

The chains go back to be original crimped
state. They might also be compared to ladders
in that the chains lie in a longitudinal position
but are connected with cross-linkages or
chemical bonds.
These cross-linkages or rungs of the ladder
help pull the fiber back to its original position
after it has been stretched.

Fig. 16: Physical structure of the wool fiber.
(Courtesy Verner Von Bergen. Reprinted by
permission of Industrial and Engineering Chemistry.)

Properties Relating to Durability
 Wool fibers are weak, having a tenacity of 1.2 to 1.7
grams per denier. Like all protein fibers, they are
weaker when wet. Fiber strength is not always an
indication of durability since flexibility of the fiber
and its resistance to abrasion are also important.
 Wool fibers are very flexible—they can be bent back
on themselves 20,000 times without breaking. (Sea
Island cotton breaks after 3,200 flexings; silk after
1,800; and rayon after 75.) The extensibility of the
fibers also makes them durable. When strain is
applied, the fiber first uncrimps, then further strain
causes the fiber to stretch up to 30 per cent of its
original length without breaking.

 Wool is a very resilient fiber. Its resiliency is greatest
when it is dry and lowest when it is wet. If a wool
fabric is crushed in the hand, it tends to spring back to
its original position when the-hand is opened. This
crease-recovery property is important in the
manufacture of fabrics because it permits energetic
mechanical treatments in finishing woolens and
worsteds.
 It is important to the consumer because it minimizes
the amount of pressing needed between dry cleanings.
Fabrics made of wool fibers are not all equally
resilient. Some of this difference is due to fiber
variation, but the kind of yam, the construction and
type of the fabric

Fig. 17: Photomicrograph of wool fiber showing cross-
section view (above) and longitudinal view (below). (From
Wernor Von Bergen and Walter Krauss, Textile Fiber Atlas.

 also contribute to resiliency. At present there is no
scientific way to measure resiliency of fibers.
 Wool also has good press retention. It takes and holds
creases well. Crease are set by use of pressure, heat,
and moisture.
 During pressing the fiber molecules adjust themselves
to the new position by forming new cross-linkages.
Creases in wool are not permanent, however, since
they can be removed by moisture.
 Wool is hygroscopic. It picks up much moisture from
the air.

On hot, humid days wool fabrics wrinkle and
get baggy much more readily than they do on
dry, cold days.
Creases in trousers also tend to come out under
the above conditions.
Rugs wear better when there is enough
humidity in the air in a room to keep the wool
from becoming brittle.

Properties Relating to Care,
Comfort, and Stability
 Wool is said to be a poor conductor of heat.
However, the amount of heat conducted along the
fiber is not the important factor in the warmth of
wool.
 Still air is one of the best insulators and it is the air
space around the fibers in the yarns and in the Fabric
which keeps the heat of the body close to the body,
this making a fabric warm. Wool fibers do not pack
well in yarns because of the natural crimp in the fiber
and because of the scale structure. This makes wool
fabrics porous capable of incorporating much air and
gives the fabrics a lofty hand.

 Wool fabrics maintain this thickness and lightness
because the resiliency of the fibers enables them to
recover from crushing and bending.
 The absorbency of wool is necessary to warmth.
Wool does not take up liquid water quickly.
 In fact it repels it, but wool does absorb moisture of
the body or the atmosphere in the form of water
vapor, without feeling damp.
 It can absorb as much as 30 per cent of its weight in
moisture without feeling wet.

 When a wool blanket or a sweater is put in water for
washing, it does not get wet quickly as cotton does,
and once wet it does not dry quickly.
 Likewise when water or liquid is spilled on a wool
garment, it tends to run off, leaving droplets which
can be quickly wiped off.
 In this respect, wool is partially water repellent. This
property is thought to be due to the protective
membrane covering the wool fiber. Wool is
hygroscopic in that it picks up moisture in vapor
form.

It also releases moisture slowly. As wool
absorbs moisture, it actually creates heat. In
winter, when people go from a dry, indoor
atmosphere into a damp, outdoor one, the heat
liberated by the moisture absorption of wool
clothing helps to protect their bodies against
the impact of the cold atmosphere.
Wool is easily charged with static electricity
by friction. This is much more noticeable on
cold, dry days when the humidity is low.

 Felting is the term applied to the progressive
shrinkage of wool.
 Wool and specialty wool fibers are the only natural
fibers which felt. Felting occurs when wool fibers are
subjected to heat, moisture, and friction.
 All of these conditions are present at the underarms
of sweaters and shirts and in the soles of socks.
 To make felting possible, a fiber must possess a
surface scale structure; it must be easily stretched and
it must possess the power of recovery from
deformation.

 While felting is not completely understood, it is
believed that the following factors explain the
phenomenon:
1. The scales interlock when subjected to moisture,
heat and friction. In this warm, moist condition the
fibers swell and the scales open up slightly and
become entangled as the fibers move. They are like
fishhooks and prevent further movement of the
fibers, thus forming a matted fabric.
2. Under the above-mentioned conditions, wool fibers
creep or migrate toward their root end. .Since the
fibers are in a random arrangement in the yarn, the
movement is in all directions.

3. Wool fibers tend to curl when wet due to a
difference in contraction between the cuticle and the
cortex.
 Felting is both an advantage and a disadvantage.
This property is utilized in making fabrics directly
from fiber without first spinning or weaving. It is
also utilized in creating certain fabric, finishes on
woven or knitted fabrics.
 Fulling or milling, a finishing operation which
shrinks the fabric, making it heavier and thicker, is
dependent on the felting property of wool. Short
wool fibers (Hock') are sometimes blown or forced
into a heavy woolen fabric and felted in place.

 In tailoring or sewing wool fabrics, extra fullness can
be shrunk into shape by pressing in the presence of
moisture.
 Felting is a disadvantage in that it makes washing of
woolens more difficult than washing of other fabrics
'and it causes the formation of boardy areas in
garments during wear.
 Satisfactory shrink-resistant treatments were
developed during World War II for garments for the
armed forces.
 After the war, these processes were released for
commercial development.

Chemical Properties
 Wool is an amphoteric substance. This means that it
will unite with and react toward both acids and bases.
Wool is fairly stable to acids; it is harmed by alkali.
 The Alkali test is a simple test which can be used by
the home maker to identify wool and wool blends.
Alkali (caustic soda) is sold on the market as lye.
 A hot 5 per cent solution will completely destroy
wool. As it disintegrates, the fiber becomes slick,
turns to a jelly-like mass, and finally goes into
solution.

Recipe for 5 percent alkali solution
1 tablespoon lye—heat to boiling
1 pint water
 The wool in a blend will disintegrate, leaving only the
materials that have been mixed with the wool.
 A knowledge of the reaction of wool in alkaline
solutions aids the consumer in care of garments
during laundering, in spot removal, and in taking
proper precautions to prevent damage from
perspiration.

It is useful to the manufacture since alkaline
solutions are used in cleaning, fulling, and
scouring.
Vat dyes are not universally, used at present
since they must be applied in alkaline solution.
'The hydrogen peroxide used in bleaching is
alkaline, and must be used carefully at
moderate temperatures.
Very little wool is bleached to a pure white.

 Much of it is used as a creamy white, in natural color, or dyed
without first bleaching. Researeh has shown how the cross-
linkages in wool can be broken and new cross-linkages built
which make the fiber more resistant to the action of alkali,
bleaches, and sunlight.
 The treated wools are also more resistant to shrinkage and to
attack by moths and bacteria. Wool is damaged by moths.
 Since wool burns very slowly, it creates no fire hayard. Wool
blankets are used to put out flames. The burning test can be
used to distinguish protein from cellulose or thermoplastic
fibers.
 Wool can be detected in a blend by the characteristic "burning
chicken feather? odor and the lack of luster of the fibers.

Wool Fiber Cleaning Processes
 The three processes listed below are wool fiber
cleaning processes :
Fig. 18. Scouring wool. Courtesy The Wool Bureau.)

 Scouring, as shown in Figure 18, is primarily
washing in a detergent and water. After scouring, the
wool is dried by passing it through chambers where
the air temperature is reduced as the wool becomes
drier. At the end of the process the wool comes out
white, soft, and fluffy.
 The solvent scouring process, dissolving fats and
oils in the wool by using volatile solvents such as
benzene, petroleum, naphtha, and carbon
tetrachloride, produces wool of superior strength and
softness since there is no damage from alkali or
partial felting. One type of solvent scouring called the
Naphthalated Process was originated by Ellen II.
Richards, founder of Home Economics, when she
was professor of chemistry at Massachusetts Institute
of Technology.

 Carbonizing is an acid bath treatment of wool fiber
or fabric to remove burrs, leaves, and other vegetable
matter. The fiber or fabric is heated to char the
foreign matter and then dusted to remove the chaired
matter.
Care
A knowledge of the physical and chemical structure
of wool helps the consumer understand how to care
for wool fabric. The scale structure protects the fiber
somewhat so that soil brushes off easily. Since the
fiber does not absorb liquid water readily, water-
borne soil can be shaken off, leaving the soil on the
surface of the fabric.

When the fabric is completely dry, this soil can
usually be brushed off. Muddy spots on children's
clothes can be removed this way.
A good brush is essential in caring for wool
garments. They should be brushed after each
wearing. Care should be given to the under
collars and the inside of cuffs on coats and
trousers. A firm, soft brush not only removes
dust but it gently tilts the fibers back to their
natural springiness. Fabrics which are damp
should lie allowed to dry before brushing.

 Garments should lie allowed to rest between wearings
so that they hang back into shape. Wool fibers recover
from deformation rather slowly, flanging over a bath
tub of hot water helps remove wrinkles. Garments
should be buns so that the air can circulate freely
about them. Wools tend to absorb odors.
 When storing woolens, be sure they are clean and free
from spots. It is best to wrap them in paper and seal
the edges.
 Wool fabrics are not harmed by dry-clean-solvents
and unless wet cleaning is necessary, there are usually
no unsatisfactory results from dry cleaning.

 Precautions must be taken when washing wool. Even
shrink-resistant wools cannot receive the rough
treatment given to cotton during washing.
 Use warm water, a mild detergent and agitate gently.
Wool should never be rubbed. Wool garments should
be washed before they become very dirty. It is best to
use several short sudsings and rinsings, rather than a
long agitation or wash period.
 Because of the harmful effects of alkali on wool, be
sure that all the detergent is removed. Wool garments
should lie placed on a flat surface to dry or hang half
over the line so that the weight is evenly distributed.
A blanket should be hung over two or three lines.

Specialty Wools
Table 9 : SPECIALTY WOOLS ARE OBTAINED
PROM THE GOAT
FAMILY AND THE CAMEL FAMILY
Goat family Camel family Others
Angora goat mohair
Cashmere goat—
cashmere
Camel's hair
Llama
Alpaca
Vicuna
Guanaco
Angora rabbit-angora
Fur Fibers
Chicken feathers

Mohair
 Mohair, the fiber from the Angora goat, has been
raised for thousands or years in Turkey. It is now bred
also in South Africa and the United States, the United
States producing the best quality Fiber.
 Angora goats in the United States have .been
developed through a long period of selective breeding
which has been accomplished by the use of imported
stock and by crossing the improved Angora males
with selected does.
 The most selected mohair comes from the goats
raised and bred in Texas.

 The raw fleece from the Angora goat is quite long and
is of a slightly yellowish or grayish tint; however,
when the fleece is washed it comes out a lustrous
white.
 Mohair is the most resilient natural fiber. It has
practically none of the crimp found in sheep's wool,
giving it a smoother surface which is more resistant
to dust and more lustrous than wool.
 Mohair is very strong and has good affinity for dyes.
Length of fiber ranges from 4 to 6 inches for half a
year's growth or double that for a year's growth.

The coarse hairs are used for interlinings for
ties, suits and coats; the fine hairs are used in
woolens and worsteds for clothing; the
medium quality fillers are used in upholstery
and rugs.
Mohair is blended with wool; silk, cotton and
rayon are also used in combination with these
fibers.

Cashmere
 The cashmere goat is smaller than the Angora goat. The name
comes from the province of Kashmer in northern India
although the main portion of the cashmere of commerce comes
from the northwestern provinces of China and outer Mongolia.
 The goat has now been domesticated and is being raised on
small farms in Tibet. Mongolia, and China. The hair is combed
by hand from the animal during the molting season.
 Two kinds of fiber are obtained from this combing; coarse,
long hairs which are exported as goat's hair, and very fine, soft
fibers which are used for the finest fabrics. This very finest in
the underdown represents only 4 per cent of the total.

The natural color of the fiber varies from white
to gray to brownish-gray. This fine fiber
consists of a mixture of fine cashmere hair
with coarse beard hair. The amount of beard
hair can vary from 10 per cent to 50 per cent of
the total, depending upon the care with which
the hand combing was done.
When this mixture of fine cashmere and beard
hair arrive in this country, through a highly
specialized process of mechanical combing
these coarse beard hairs are removed.

 The yield of this finished product which goes into the
manufacturing of fine cashmere fabrics is probably
not more than one-half pound per goat.
 Cashmere is one of the finest, softest, smoothest, and
most beautiful fibers used by man. It has always been
associated with beautiful, costly fabrics.
 There are so many qualities of cashmere that just the
name "cashmere" does not necessarily indicate the
finest quality, and care should be taken by the
consumer when purchasing a cashmere fabric.

Camel Hair
 Camel's hair is obtained from the Hadrian or two-hump camel
of Mongolia and Tibet. The camel is primarily a beast of
burden, its hair being of secondary importance.
 Its coat, however, keeps the camel warm when subjected to the
extreme cold and blizzards countered in high mountain passes,
and also keeps the camel cool in the hot, dry sands of the
desert.
 It is interesting to note the manner in which the hair is
obtained, being neither sheared nor plucked as it is with most
other animals. In the spring as the weather gets warmer, the
hair-begins to form matted strands and tufts which hang from
the head, sides, neck, and legs. This falls off in clumps.

 In a caravan of camels there is a man trailing the last camel
who is the "trailer," and it is his task to pick up the hair as it
drops from the camel and place it in baskets which are
strapped to the last camel in the caravan for this purpose. He
also gathers this hair in the morning at the spot where the
camels lay down for the night.
 When the caravan readies the end of its journey, the hair is
sold at the market and then sorted and graded before being
exported throughout the world.
 The camel hair is sorted into three qualities. The number one
quality, which is next to the skin of the camel, is a short, soft
fiber that is a pale tan color. This is the quality which is used in
most fine fabrics. Quality number two is the fiber which lies
on top of the first sort and is a combination of the outer hair
and the soft down. Quality number three is the outer hair of the
animal and is coarse, tough, and wiry, and this is used for
ropes, press cloths, and likewise.

 Because camel's hair gives warmth without weight, it has been
prized as a coating fabric. Sheep's wool, dyed a camel color
and blended with a small amount of camel's hair, has been sold
as camel's hair.
 To protect consumers and manufacturers from this
misrepresentation of merchandise, it was suggested that labels
indicating the percentage of wool and camel's hair be used.
This, however, did not prove satisfactory since there are so
many different qualities of camel's hair that the percentage of
camel's hair alone did not indicate quality of the fabric. The
best way for buyers to judge quality of camel's hair is by feel.
 Consumers should be guided by the reputation of the
manufacturer or the retailer.

Silk
 Historical Reviw
Silk is often referred to as "the queen of the fibers." Chinese
legends tell us that silk was discovered in 2640 b.c. by a
Chinese empress.
The Chinese carefully guarded their secret of the silk cocoon
for 300 years. They wove beautiful fabrics which were sold to
Eastern traders who carried them back to their own countries
where they were prized very highly.
The demand for silk thus created was very great. In 300 a.d.,
refugees from China took cocoons into Korea and started
raising silk-worms.

 Japan learned about sericulture from the Koreans.
The industry spread through central Asia into Europe.
By the 12th Century Italy was the silk center of
Europe. This leadership was taken over by France in
the 17th Century.
 Weaving of silk became important in England after
the revocation of the Edict of Nantes in 1685 when
the Huguenot weavers emigrated from France to
England.
 Sericulture Silk can be produced in any temperate
climate but it has only been successfully produced
where there is a cheap source of labor.

Silk is a continuous-filament protein fiber
produced by the silkworm (Fig.19).
Cultivated silk is obtained by a carefully
controlled process in which the silkworm lives
a coddled and artificial life especially for the
purpose of producing fibers.
Wild silk production is not controlled; instead,
these Silkworms feed on oak leaves and spin
cocoons (Fig.19) under natural conditions.

Fig. 19: Silkworm, moth, and cocoon.

 Sericulture is the name given to the production or
cultivated silk. The process begins with the silk moth
(Fig.19) which lays eggs on specially prepared paper.
 The eggs are kept in cold storage until they are
needed for hatching. Hatching takes place
continuously throughout the mulberry growing-
season, thus making it possible to keep labor and
equipment at a minimum.
 The eggs are hatched into caterpillars which are put
on special mats and fed fresh, young mulberry leaves.

 When the silkworm is grown, it spins a double strand
of silk fibers surrounded by a water soluble substance
called sericin. The silkworm surrounds itself with the
fiber which it forms , into a cocoon.
 The bulk of the silk moths are killed inside the
cocoons by heat and only those which are needed for
reproduction are allowed to emerge. The pierced
cocoons are used for staple fiber.
 It is possible to control the fineness, uniformity, and
strength of the silk fiber by selective breeding, and
better silk is resulting

Fig. 20. Winding silk filaments from
several cocoons on a reel.

Processing Silk (from Fiber to Yarn)
 Reeling or unwinding the filaments from the cocoon
is done in an establishment called a filature. Until 50
years ago reeling was done by hand. The
conventional system of reeling described below still
requires much hand labor.
 A number of filaments from several cocoons are
gathered together onto an aluminum reel (Fig. 20).
One operator can handle a basin of 20 spindles (5 to 8
cocoons to one spindle).
 The operator determines the denier of the yarn solely
by eyesight. The silk is rewound, twisted into a skein
(Fig. 21), and packaged for shipping.

 The skeins are packaged into books (30 skeins to a
book) weighing 4½ Ibs. Twenty to thirty books are
formed into bales for shipment. When the silk
arrives at the mill, it is opened, bunched, soaked,
dried, and wound on bobbins. (See Fig. 22.)
Fig. 21: Skeins of silk.

Processing silk In the mill.
Fig. 22:

 Automatic or Direct Reeling
In 1952, there were four automatic silk reelers
in operation. In automatic reeling, the silk
fibers are laced from the cocoon through a
guide to a chemical bath which softens the
thread.
The filaments go around a revolving horizontal
roller, which dries the filaments and winds
them onto a spool or cone ready for weaving
on delivery. Silk in this form has a higher

Fig. 23: Photomicrograph of silk fiber; longitudinal
view.(From Werner Von Bergen and Walter Krauss, Textile
Fiber Atlas. Copyright 1949 by Textile Book Publishers, Inc.)

import duty. In addition to speeding up the
process of winding the filament, the automatic
reeler also has a cocoon finding-feeding
mechanism which regulates the size and
uniformity of the yarn.
Uniform yarns are more suitable for weaving
on high-speed looms than are hand reeled silk
yarns which slow up the weaving process. This
machine increases production three or four
times and cuts labor by 70 per cent, since one
operator can manage 400 to 600 spindles.

Kinds of Silk
1. Silk refers to cultivated silk.
2. Wild or Tussah silk is a tan-colored fiber from the
uncultivated silkworm, which feeds on scrub oak.
The cocoons are always pierced, so the fibers are
shorter than reeled silk. Shantung, pongee, and
honan are fabrics made from wild silk.
3. Doupion silk comes from two silkworms who spin
their cocoons together. The yarn is uneven, irregular,
and large in diameter.

4. Raw silk refers to cultivated silk-in-the-gum. Raw
silk varies in color from gray-white to canary
yellow but since the color is in the sericin, boiled-
off silk is white.
5. Reeled silk is the long continuous filament, 500 to
1600 yards in length.
6. Spun silk refers to yarns made from silk from
pierced cocoons and waste silk.
7. Waste silk is comprised of the tangled mass of silk
on the outside of the cocoon and the fiber from
pierced cocoons.

Properties
Silk has a desirable combination of properties:
smoothness, soft luster, resiliency,
toughness, and adaptability to
temperature— which is not found in any of
the new fibers. Its individual properties have
been duplicated and in many cases excelled,
but this particular combination is found only in
silk.

Physical Structure and
Appearance
Silk is the only natural filament. It is a solid
fiber but unlike the man-made fibers is not
uniform in size (Fig. 23).
The filaments are 300 to 1800 yards long. In
cross section (Fig. 24) the fibers are like
triangles with rounded corners. The rod-like,
almost circular fibers are responsible for the
luster of silk.

Other Properties
1. Silk is a strong fiber and is high in resiliency. Silk is
said to be a poor conductor of heat. However, it is
cool in summer because of the smoothness of the
fibers and is comfortable in both winter and
summer because it is absorbent. Silk builds up static
electricity.
2. Scroop, a-special property of silk, is not in herein: in
the fiber but can be obtained by dipping rue fabric in
dilute acetic or tartaric acid and drying without
rinsing. This produces the rustling or crunching
property of silk.

Fig.24: Photomicrograph of cross section of silk fiber. (From
Werner Von Bergen and Werner Krauss, Textile Fiber Atlas.
Contrary to popular opinion, scroop does not enhance the true
quality or real value of silk.

3. Silk is not harmed by moths. It is less sensitive to
alkali than wool. However, mild soaps should be
used because luster is diminished by the use of
strong alkalis. Hand washing is preferable. Sunlight
and chlorine bleaches damage silk fiber and cause it
to turn yellow. The yellowing of silk has been
studied but has not been solved as yet. High ironing
temperatures cause a yellowing of the fiber.
Researeh is also being done on this problem.
4. Silk takes dyes well and it seems to have, a depth of
color or jewel-like tone not found in the man-made
fibers which look like silk. Fast colors are available
but many converters need to be educated to use
them. Brilliant colors are often not fast to washing.

5. 5-Silk is sold and usually woven "in-the-gun." The
seracin makes up about one-fourth of the fiber
weight and is removed by degumming. This is done
by washing if in hot water and soap or synthetic
detergent for two to four hours, then rinsing one to
three hours in clear, hot water. In order to
compensate for the loss of gum or sericin, weighting
can be added. Iron, tin, or lead salts are used. Silk
will absorb up to 400 per cent. A small amount of
weighting is desirable to give good draping
qualities, but an excessive amount weakens the fiber
so that it breaks and abrades more easily than
unweighted silk.

6. In 1938, the Federal Trade Commission passed
rulings on the labeling of silk fabrics. The term
"Pure Dye Silk" refers to silk (other than black)
which contains metallic salts up to 10 per cent.
"Pure Dye Silk" may be used on black silks which
have been weighted up to 15 per cent. These rulings
refer to silk in the United States only. The term
"Pure Dye" is used because the weighting is done
during the dyeing process. Weighted silk does not
burn like other protein fibers. It chars and holds its
shape; the metal glows like the filament in a light
bulb when in contact with the flame. The odor of
burning chicken feathers is noticeable. Weighting
was prohibited during World War II and silk fabrics
on the market since then contain little or no
weighting.

7. Water spotting, caused by migration of
weighting agents to the outer edge of
the spot, was one of the early problems
of silk. Most manufacturers are now
using a water spotresistant finish.

Man-Made Cellulosic Fiber:
Rayon
(The Regenerated Cellulose Fiber)
Rayon was the first man-made fiber. The idea that
man could make a fiber was suggested by Robert
Hooke in 1665, in his book, Micrographia. For a
period of: 300 years, scientists tried to make a
practical application of this idea.
A Swiss chemist, Georges Audemars, in 1855,
succeeded in making a solution from cellulose. He
made his filaments by dipping a needle into the
solution and drawing out a strand and then winding it
onto a reel. This method of spinning was, of course,
too slow to be practical.

 Two years later, Schweitzer discovered that cellulose
dissolves in cuprammonium solution (Schweitzer's
reagent). This is the basis for the cuprammonium
process used today to make Bemberg rayon.
 Sir Joseph Swan, an English, physicist, forced a
solution through a fine hole into a hardening bath and
discovered the first practical method of spinning a
fiber.
 Rayon was first produced commercially in France by
Count Hilaire de Chardonnet in 1889. He is said to be
the father of the rayon industry. This rayon was
produced by the nitrocellulose process.

 A regenerated fiber is one which has a different physical
structure than the substance from which it is made, but is
essentially the same chemically. Rayon is Regenerated
Cellulose, i.e., a cellulose that has gone through the
manufacturing process, from solid to liquid to solid, without
chemical change.
 Two types of rayon, viscose and cuprammonium, are made of
regenerated cellulose, and their differences are due to the
differences in the chemicals used to put the cellulose into
solution.
 The flow chart (Fig. 25 page 42) and the chart on page 46
show the difference in the spinning solutions and in the
treatment as the yarn comes from the spinnerette in the two
processes.

The Viscose Process
 The starting material for viscose, usually wood pulp,
is purchased as sheets of purified cellulose. These
sheets are placed in presses, two to each division, and
steeped in caustic soda (mercerised) for 30 to 60
minutes.
 They are then squeezed by a hydraulic ram to remove
excess liquid, taken from the presses and dropped
into a shredding machine (Fig. 26 & 27) which breaks
up the pulp into small crumbs. 'These alkali-cellulose
crumbs are aged for one to three days.

Fig. 25: Viscose flow chart. (Courtesy
American Viscose Corporation.)

Fig. 26: The manufacture of viscose rayon-
the steeping process. (Courtesy American
Viscose Corporation.)

Fig. 27: Manufacture of viscose rayon: a
shredding machine. (Courtesy American
Viscose Corporation.)

After ageing, the crumbs are treated with
carbon disulfide, which causes the crumbs to
change from white to orange and to change
chemically so they will dissolve readily. This
process is called xanthation.
The crumbs are then treated with a dilute
solution of caustic soda which converts them
to a liquid known as viscose solution.

Fig. 28: Bright and dull rayon yarns. (Courtesy
American Viscose Corporation.)

The luster of rayon is controlled at this point
by the addition of a delustering agent, usually
titanium dioxide (Fig. 28) Color can also be
added to the spinning solution at this time.
The viscose solution is allowed to stand (age)
for 4 to 5 days.
It is filtered to remove air bubbles and
insoluble particles and is then pumped through
spinnerettes into an acid bath.

Dyes and Textile Dyes and Textile Dyes Dyes and Textile

Dyes and Textile Dyes and Textile Dyes Dyes and Textile

Recommended

Recommended

More Related Content

Similar to Dyes and Textile Dyes and Textile Dyes Dyes and Textile

Similar to Dyes and Textile Dyes and Textile Dyes Dyes and Textile (20)

Recently uploaded

Recently uploaded (20)

Dyes and Textile Dyes and Textile Dyes Dyes and Textile