PREFACE

The dissertation is a report of the work carried out by the author, at

Chemistry laboratory, Chellappan Vidya Mandir International
School, Karaikudi, during the period of 2017-2018 it deals with
Dyeing of fabrics. The dissertation is broadly divided into

The Chapter - I gives information about dye, types of dyes and its
characteristics.

The Chapter - II deals with dyeing, methods of dyeing and processes

involved in dyeing.

The Chapter - III deals with the types, advantages and disadvantages
of dyeing machines.

The Chapter - IV gives information about Malachite green. The

structure, preparation and uses of malachite green are also
explained.

The Chapter - V gives detailed information about the experiment:

Dyeing of Fabrics.

1
 CONTENTS
CHAPTER: 1
1.1 Dye-introduction
1.2 Natural Dyes
1.3 Synthetic dyes
1.4 Types of dyes

CHAPTER: 2
2.1 Dyeing
2.2 Methods of dyeing

CHAPTER: 3
3.1 Dyeing machines
3.2 Jigger dyeing machine
3.3 other types of machines

CHAPTER: 4
4.1 Malachite green
4.2 structure and preparation
4.3 uses

CHAPTER: 5
5.1 Aim
5.2 procedure and observation

5.3 conclusion
BIBLIOGRAPHY
2
DYEING AND FABRICS

3
 CHAPTER-1
DYE
INTRODUCTION
A dye is a coloured substance that has an affinity to the substrate to
which it is being applied. The dye is generally applied in an aqueous
solution, and may require a mordant to improve the fastness of the
4
dye on the fibre. Dye is used to impart colour to textiles, paper,
leather and other materials such that the colouring is not readily
altered by washing, heat, light or other factors to which the material
is likely to be exposed. Examples are alizarin, indigo, Congo Red,
etc.
Both dyes and pigments are coloured because they absorb some
wavelengths of light more than others. Dyes differ from pigments,
which are finely ground solids dispersed in a liquid, such as paint or
ink, or blended with other materials. Most dyes are organic
compounds (i.e., they contain carbon), whereas pigments may be
inorganic compounds (i.e., they do not contain carbon) or organic
compounds. Pigments are insoluble and have no affinity for the
substrate.
Throughout history dyes and pigments have been major articles of
commerce. Manufacture of virtually all commercial products
involves colour at some stage, and today some 9,000 colorants with
more than 50,000 trade names are used. The large number is a
consequence of the range of tints and hues desired, the chemical
nature of the materials to be coloured, and the fact that colour is
directly related to the molecular structure of the dye.

NATURAL DYES
Natural dyes are dyes or colorants derived from plants,
invertebrates, or minerals. The majority of natural dyes are
vegetable dyes from plant sources-roots, berries, bark, leaves, and
wood-and other organic sources such as fungi and lichens.
Archaeologists have found evidence of textile dyeing dating back to
the Neolithic period. In China, dyeing with plants, barks and
insectshas been traced back more than 5,000 years. The essential
process of dyeing changed little over time. Typically, the dye
material is put in a pot of water and then the textiles to be dyed are
added to the pot, which is heated and stirred until the colour is

5
transferred. Textile fibre may be dyed before spinning ("dyed in the
wool"), but most textiles are "yarn-dyed" or "piece-dyed" after
weaving early dyers. Many natural dyes require the use of chemicals
called mordants to bind the dye to the textile fibres; tannins from
oak galls, salt, natural alum, vinegar and ammonia from stale urine
were used by early dyers.

SYNTHETIC DYES
Synthetic dyes are man-made. These dyes are made from synthetic
resources such as petroleum by-products and earth minerals. In 1856
the first commercially successful synthetic dye, mauve, was
serendipitously discovered by British chemist William H. Perkin,
who recognized and quickly exploited its commercial significance.
The introduction of mauve in 1857 triggered the decline in the
dominance of natural dyes in world markets.

6
 TYPES OF DYE

ACID DYES are water-soluble anionic dyes that are applied to

fibres such as silk, wool, nylon and modified acrylic fibres using
neutral to acid dye baths. Attachment to the fibre is attributed, at
least partly, to salt formation between anionic groups in the dyes and
cationic groups in the fibre. Acid dyes are not substantive to
cellulosic fibres. Most synthetic food colours fall in this category.
Examples are Orange I and Orange II.

BASIC DYES are water-soluble cationic dyes that are mainly

applied to acrylic fibres, but find some use for wool and silk.
Usually acetic acid is added to the dye bath to help the uptake of the
dye onto the fibre. Basic dyes are also used in the colouration of
paper. Examples are aniline yellow and butter yellow.

DIRECT OR SUBSTANTIVE DYE is normally carried out in

neutral or slightly alkaline dye bath, at or near boiling point, with
the addition of either sodium chloride (NaC1) or sodium sulphate
(Na2SO4) or sodium carbonate (Na2CO3). Direct dyes are used on
cotton, paper, leather, wool, silk and nylon. They are also used as
pH indicators and as biological stains.

DISPERSE DYES were originally developed for the dyeing of

cellulose acetate and are water-insoluble. The dyes are finely ground
in the presence of a dispersing agent and sold as a paste or spray-
dried and sold as a powder. Their main use is to dye polyester, but
they can also be used to dye nylon, cellulose triacetate and acrylic
fibres. In some cases, a dyeing temperature of 130C (266 F) is
required and a pressurized dye bath is used. The very fine particle
size gives a large surface area that aids dissolution to allow uptake
by the fibre. The dyeing rate can be significantly influenced by the
choice of dispersing agent used during the grinding. Examples are
celliton fast pink B and celliton fast blue B.

7
VAT DYES are essentially insoluble in water and incapable of
dyeing fibres directly. However, reduction in alkaline liquor
produces the water-soluble alkali metal salt of the dye, which, in this
leuco form, has an affinity for the textile fibre. Subsequent oxidation
reforms the original insoluble dye. The colour of denim is due to
indigo, the original vat dye. Example: Indigo.

REACTIVE DYES utilize a chromophore attached to a

substituent that is capable of directly reacting with the fibre
substrate. The covalent bonds that attach reactive dye to natural
fibres make them among the most permanent of dyes. "Cold"
reactive dyes, such as Procion MX, Cibacron F and Drimarene K are
very easy to use because the dye can be applied at room temperature.
Reactive dyes are by far the best choice for dyeing cotton and other
cellulose fibres at home or in the art studio.

MORDANT DYES require a mordant, which improves the

fastness of the dye against water, light and perspiration. The choice
of mordant is very important as different mordants can change the
final colour significantly. Most natural dyes are mordant dyes. The
most important mordant dyes are the synthetic mordant dyes or
chrome dyes, used for wool; these comprise some 30% of dyes used
for wool, and are especially useful for black and navy shades. The
mordant, potassium dichromate, is applied as an after- treatment. It
is important to note that many mordants, particularly those in the
heavy metal category, can be hazardous to health and extreme care
must be taken in using them.

INSOLUBLE DYES are directly synthesised on the fibre. The

fabric to be coloured is soaked in alkaline solution of phenol and
then treated with a solution of diazotised amine to produce azo dye.
The colour induced by such dyes is not fast. These dyes are used for

8
dyeing of cotton, silk, polyester nylon, etc .For example, nitroaniline
red.

CHARACTERISTICS OF A DYE
It must have a suitable colour.
It must be capable of being fixed to the material.
When fixed it must be fast to detergents, soaps, water, dry-
cleaning solvents, light and dilute acids.

9
CHAPTER-2
10
 DYEING
Dyeing is the process of adding colour to textile products like fibres,
yarns and fabrics. Dyeing is normally done in a special solution
containing dyes and particular chemical material. After dyeing, dye
molecules have uncut chemical bond with fibre molecules. The
temperature and time controlling are two key factors in dyeing.
Since the mid- 19th century, humans have produced artificial dyes to
achieve a broader range of colours and to render the dyes more
stable to resist washing and general use. Different classes of dyes
are used for different types of fibre and at different stages of textile
production process, from loose fibres through yarn and cloth to
complete garments.
Acrylic fibres are dyed with basic dyes while nylon and protein
fibres such as wool and silk are dyed with acid dyes, and polyester
yarn is dyed with disperse dyes. Cotton is dyed with a range of dye
types, including vat dyes, and modern synthetic reactive and direct
dyes.

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METHODS OF DYEING
Colour is applied to fabric by different methods of dyeing for
different types of fibre and at different stages of textile production
process. Dyeing can be done during any stage in the textile
manufacturing process. Textiles may be dyed as fibre, as yarn, as
fabric, as garments, depending upon the type of the fabric or
garment being produced. These methods include:
Direct dyeing
Stock dyeing
Top dyeing
Yarn dyeing
Piece dyeing
Garment dyeing
Solution pigmenting or dope dyeing etc.

Of these Direct dyeing and Yarn dyeing methods are the most
popular ones.

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 DIRECT DYEING

When a dye is applied directly to the fabric. without the aid of an

affixing agent, it is called direct dyeing. In this method the dyestuff
is either fermented as in case of natural dye or chemically reduced
as in case of synthetic vat and sulphur dyes before being applied.
This renders the dye soluble so that it can be absorbed by the fibre
since the insoluble dye has very little substantively to the fibre.
The direct dyes, which are largely used for dyeing cotton are water
soluble and can be applied directly to the fibre from an aqueous
solution. Most other classes of synthetic dye, other than vat and
sulphur dyes, are also applied in this way.

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 YARN DYEING

Yarn dyeing is the dyeing of the yarns before they have been
woven or knitted into fabrics. Yarn dyeing is used to create
interesting checks, stripes and plaids with different-coloured
yarns in the weaving process. In yarn dyeing, dyestuff penetrates
the fibres in the core of the yarn.
There are many forms of yarn dyeing. Common forms are
thepackage form and the hanks form. Cotton yarns are mostly dyed
at package form and acrylic or wool yarn is dyed at hank form. In
the continuous filament industry, polyester or polyamide yarns are
always dyed at package form, while viscose rayon yarns are partly
dyed at hank form because of technology.

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 GARMENT DYEING
Garment dyeing is the process of dyeing fully fashioned
garments such as pants, pullovers, T-shirts, jeans, sweaters,
dresses, skirts, etc subsequent to manufacturing, as opposed to the
conventional method of manufacturing garments from pre-dyed
fabrics.

DOPE DYEING

This is also called dope dyeing or spun dyeing; the pigment colour
is bonded-in in the solution and is picked up as the filaments are
being formed in the liquor. Cellulosic and non-cellulosic fibres are
dyed to perfection by this method. The colours are bright, clear,
clean and fast.

GARMENT DYEING

Garment dyeing is the process of dyeing fully fashioned

garments such as pants, pullovers, T-shirts, jeans, sweaters,
dresses, skirts, etc subsequent to manufacturing, as opposed to the
conventional method of manufacturing garments from pre-dyed
fabrics.

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 STOCK DYEING

Stock dyeing refers to dyeing a staple fibre before it is spun. There

are two methods. The older and widely practiced procedure is
that of removing the packed fibre from the bales and then
packing the stock in large vats and circulating dye liquor through
the mass of fibre at elevated temperatures.

TOP DYEING
One step neater to the finished yarn than stock dyeing is what
is called top dyeing in the worsted industry. Top is wool that
has been combed to take out the short fibres, then delivered from
the combs in a rope like form about 1.25'.' the top is wound on
perforated spools and the dye liquor is circulated through it.
Very even dyeing is possible with this method.

PIECE DYEING
The dyeing of cloth after it is being woven or knitted is
known as piece dyeing. It is the most common method of
dyeing used. The various methods used for this type of dyeing
include jet dyeing, jig dyeing, pad dyeing and beam dyeing.

16
 PROCESS OF DYEING

The dyeing of a textile fibre is carried out in a solution,

generally aqueous, known as the dye liquor or dye bath. For true
dyeing to have taken place, coloration of fabric and absorption are
important determinants.
Coloration: The coloration just be relatively permanent: that is not
readily removed by rinsing in water or by normal washing
procedures. Moreover, the dyeing must not fade rapidly on exposure
to light.
Absorption: The process of attachment of the dye molecule to the
fibre is one of absorption: that is the dye molecules concentrate on
the fibre surface. There are four kinds of forces by which dye
molecules are bound to the fibre:

Ionic forces
Hydrogen bonding
Vander Waal's forces
Covalent chemical linkages

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CHAPTER-3
18
 DYEING MACHINES

Dyeing machine is the device that is used by different industries

for imparting colours. From paper to plastic to textiles
everywhere there is use of dyeing machinery. According to the
need of each type of substrate, different set of machines are put
to use.
The dyeing machine helps in providing correct and effective
dye liquor interchange for goods. Also dyeing machine
helps in monitoring and effective control rate of temperature rise
and holding on at the set dyeing temperature. In the textile
industry a variety of dyeing machine is used for dyeing. Some
of these dyeing machines with minor operational can easily
accommodate new types of dyes and take advantages of the
latest advances made in the dyeing equipment technology.

Some of the important of them are

Jigger Dyeing Machine

Winch Dyeing Machine

Jet Dyeing Machine

Padding Mangle

Package Dyeing Machine

High Pressure High Temperature Dyeing Machine (Beam

Dyeing Machine)

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 JIGGER DYEING MACHINE

Jigger dyeing machine is the most commonly used for dyeing

all kinds of cotton fabric. There are mainly two types of jigger
dyeing machine. One is open jigger dyeing machine and other is
closed jigger dyeing machine. The open jigger dyeing machine is
shown in the figure. This machine consists of V shaped stainless
steel vessel. Two rollers are fitted above the vessel called as cloth
rollers. These rollers are rotated by power. Out of these two rollers
one roller is driven by a
motor which is called take up roller and the other roller from
which the cloth is delivered is called let off roller. When all
the cloth is passed from the let off roller to the take up roller, it
is called as one end or one turn. The number of ends or turns
depends upon the type of the fabric and also the percentage of the
shade. Initially, a large length of (50 kg) cloth is wound on the let
off roller and take up roller is then driven by the power. After
one end is taken, the take up becomes let off roller. These
backward and forward movements of cloth through the dye liquor
absorb more and more dye. The capacity of the jigger is 100 to
150 gallons. In the modern jigger, automatic devices are fitted
along with the timing switch by using reversing will take place
automatically. When dyeing all the dye liquor should not be
added at one time. The dye liquor should be added in batch wise,
in order to get even shade on the cloth.

ADVANTAGES
The cloth can be dyed in open width form of full width form.
Chemical and heat loses are less when compared to winch
dyeing machine
The material to liquor ratio rs 1:3 (or) 1:4 which saves

20
considerable amount of chemical cost and steam cost.

DISADVANTAGES
It exerts lot of tension in the warp direction and because of this
normally woollen, knitted fabrics, silk etc are not dyed in jigger
dyeing machine.

WINCH DYEING MACHINE

Winch dyeing machine is normally used for dyeing light
weight fabrics like knitted fabrics as well as woven, silk etc.
The winch dyeing machine is different in construction from
the jigger. The machine consists of elliptical winch (or)
circular winch which is driven by hand or motor. Elliptical
winches are most widely used. It has a perforated portion dividing
the machine in to two compartments. One is small and the other
one is bigger in size. Dye- liquor pipe, steam pipe, water inlet
are provided in small compartment. Dyeing is
carried out in the larger compartment. During working, one end of
the fabric is passed over the guide rollers and winch and under the
dye liquor and passed in between the pegs. After the sufficient
amount of cloth is fed the ends are stitched and making a long
continuous loop formation. Many such loops run together
separately by a series of pegs, to avoid entanglements. The loops
are drawn in and out of the bath by rotating the winch. After
dyeing is over the pieces are separated. The winch is made
up of stainless steel. Now-a-days closed type of winch is also
used to prevent the temperature loss and pressure loss.

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 ADVANTAGES
Thin and light weight fabrics like knitted fabrics, voile cloth etc,
can be dyed successfully in winch dyeing machine without exerting
any tension. Embroidery fabrics may be dyed in winch dyeing
machine without affecting the embroidery designs.

DISADVANTAGES
Fabrics are dyed in rope form, so there are more chances for uneven
dyeing. Therefore, we will get even dyeing only when retarding
levelling agent is added to the dye liquor. The material to liquor
ratio
is very high i.e. 1 :30 or 1 :40. Therefore the heat and the
additional chemicals are provided more when compared to jigger.
Heat and chemical losses are more because of the wider open tank.

PADDING MANGLE

Continuous dyeing methods depend upon the impregnation with the

padding mangles. The padding mangles are equipped with two, three
or even four mangles. The rollers are arranged one above the other.
Three bowl padding mangle are usually prepared dyeing of cloth.
The padding mangle consists of ebonite rollers and one rubber
covered roller. To reduce the material to liquor ratio, low capacity
troughs are generally used with different shapes. Some of the .
machines are provided jacket troughs for maintaining the
temperature of pad liquor. An over head tank is connected to the
mangle for feeding the stock solution through the perforated pipe.
The supply of the dye - liquor is controlled automatically to
maintain a constant level. The pressure on the padding mangle is
applied by hydraulic or pneumatic system which enables heavier

22
and uniform pressure.The trough is fitted with dye - liquor and the
cloth passes through the dye solution, which is heated by steam.
After that the cloth is passed between the ebonite and rubber
covered roller to give uniform pressure throughout the fabric. The
pressure can be altered depending upon the type of fabric. The speed
is 200 yards per minute. It is used for dyeing vat, sulfur, naphthol,
etc. The solution used in the trough is divided into equal portions
to avoid uneven dyeing. The padding mangles may also be used
for desizing purposes.

FEATURES

Ergonomic design
Rugged structure
Efficient performance
Provide protection
Heat resistant

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 JET DYEING MACHINE

This is the most modern machine used for the dyeing of

polyester using disperse dyes. In this machine the cloth is dyed
in rope form which is the main disadvantage of the machine, In
this machine, the dye tank contains disperse dye, dispersing
agent, levelling agent and acetic acid. The solution is filled up in
the dye tank and it reaches the heat exchanger where the solution
will be heated which then passed
on to the centrifugal pump and then to the filter chamber. The
solution will be filtered and reaches the tubular chamber. Here
the material to be dyed will be loaded and the winch is rotated, so
that the material is also rotated. Again the dye liquor reaches the
heat exchanger and the operation is repeated for 20 to 30 minutes
at 1350 C. Then the dye bath is cooled down, after the material is
taken out. Metering wheel is also fixed on winch by external
electronic unit. Its purpose is to record the speed of the
fabric. The thermometer, pressure gauge is also fixed in the
side of the machine to note the temperature and pressure under
working. A simple device is also fixed to note the shade under
working.

24
ADVANTAGES

Dyeing time is short compared to beam dyeing.

Material to liquor ratio is 1 :5 or 1 :6.
Production is high beam dyeing machine.

DISADVANTAGES

Cloth is dyed in rope form.

Risk of entanglement.
Chance for crease formation.

PACKAGE DYEING MACHINE

A series of technical development in the recent years has resulted
into package dyeing being developed into a highly sophisticated
as well as an economic process. Latest design Package Dyeing
machines are amenable to accurate control and automation.
These features would likely to lead to increases in the
application on of package dyeing. The term package dyeing
usually denotes for dyeing of yarn that has been wound on
perforated cores. This helps in forcing the dye liquor through t he
package. With the start of dyeing cycle, the dye liquor goes on
circulating throughout the vessel and tank This happens till all
the dye is used up or fully exhausted. The dye flows through to the
yarn package with the help of the deliberate perforations in the
tube package. Once full exhaustion is brought about, the
carrier of coloured yarn is consequently removed from the
vessel. A large centrifuge removes excess water from the
packages. Finally the yarn is dried using an infra red dyeing oven.

25
ADVANTAGES
Package dyeing methodologies have been subjected to
intensive research and development. As a result package dyeing
machine has evolved into a very sophisticated apparatus. It offers a
number of advantages.
Considerable reduction in yarn handling.
Compatible to automatic control in the process
leading to reproducible dyeing.
Open to large batches.
High temperature dyeing possibility.
Low liquor ratios, giving savings in water, effluent and energy.
Uniform and high rates of liquor circulation, that leads to
level application of dyeing.
Machinery totally enclosed resulting in good working
conditions at the dye-house.

BEAM DYEING MACHINE

The beam dyeing machine operates with the same principle as that
of package dyeing machine. It can be effectively used to dye
yarn or fabric. The process works like this, fabric or yarn in
open width is rolled on to a perforated beam. The beam then
subsequently slid into a vessel that is closed and pressurized.
The colour impregnates the fabric as the dye liquor is allowed
to go on circulating through the perforations in the beam.
Usually the beam machines are designed in such a manner so as
to hold a single beam or multiple beams in a
batch.

FEATURES
Able to adjust water level in accordance to fabric volume.
26
Even dyeing and superior dyeing quality.
Optimized circulation system along with high performance
pumps.
ADVANTAGES
The fabric is put under controlled tension, and is wound on to
aperforated beam. This results in elimination of creases from the
fabric. It also ensures total control of the dimensions of the roll of
fabric.
The fabric is not allowed to do any movement during the process
of dyeing. This actually means that there is no application
mechanical action on to the fabric. There is no movement of the
fabrics as the hydrostatic pressure of the pump forces the dye
liquor through the fabric roll.

27
CHAPTER-4
28
 MALACHITE GREEN-DYE

Malachite green is an organic compound that is used as a dyestuff

and controversially as an antimicrobial in aquaculture. Malachite
green is traditionally used as a dye for materials such as silk,
leather and paper. The dye occurs as lustrous green crystals and
is soluble in water and alcohol. Although called malachite
green, this dye is not prepared from the mineral malachite - the
name just comes from the similarity of colour. Malachite green is
also called aniline green, benzaldehyde green or china green.
Malachite green is effective against fungi and gram-positive
bacteria. In the fish-breeding industry it has been used to control
the fungus
Saprolegnia, a water mould that kills the eggs and young fry .

STRUCTURE
Malachite green is classified in the dyestuff industry as
triarylmethane dye and also using in pigment industry. Formally,
malachite green refers to the chloride salt [C6H5C (C6H4N
(CH3)2)2]Cl, although the
term malachite green is used loosely and often just refers to
the coloured cation. The anions have no effect on the colour

PREPARATION
Malachite green is prepared by the condensation of benzaldehyde
and dimethylaniline to give leuco-malachite green (LMG):
Second, this colourless leuco compound, a relative of triphenyl
methane, is oxidized to the cation that is MG:A typical oxidizing
agent is manganese dioxide .
29
 USES OF MALACHITE GREEN

Malachite green is traditionally as a dye for materials like silk,

leather and paper. Millions of kilograms of MG and related
triarylmethane dyes are produced annually for this purpose. The
dye occurs as lustrous green crystals and is soluble in water and
alcohol. Although called malachite green, this dye is not prepared
from the mineral
malachite-the name just comes from the similarity of colour
Malachite green is active against the oomycete Saprolegnia,
which infects fish eggs in commercial aquaculture. MG has been
used to treat Saprolegnia and is used as an antibacterial. It is very
popular treatment against lchthyophthirius multifiliis in freshwater
aquaria.
Malachite green has frequently been used to catch thieves and
pilferers. The bait, usually money, is sprinkled with the
anhydrous powder. Anyone handling the contaminated money will
find that on upon washing the hands, a green stain on the skin that
lasts for several days will result.
It is used as a biological stain for microscopic analysis of cell
biology and tissue samples. Malachite green can also be used as a
saturable absorber in dye lasers, or as a pH indicator between pH
0.2-1.8. However, this use is relatively rare.

30
HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
H

CHAPTER-1
31
 DYEING OF FABRICS

AIM: To dye wool and cotton clothes with malachite dye.

REQUIREMENTS: 500 ml beakers, tripod stand, wire gauze,
glass rod, spatula, wool cloth and cotton cloth, Sodium
carbonate, Tannie acid, Tartar emetic and malachite green dye.
PROCEDURE:
Preparation of Sodium carbonate solution: Take about 0.5 g
of solid sodium carbonate and dissolve it in 250 ml of water.
Preparation of Tartar emetic solution: Take about 0.2 g of
tartar emetic and dissolve it in 100 ml of water by stirring
with the help of glass rod.
Preparation of Tannie acid solution: Take 100 ml of water
in a beaker and add about 1.0 g of tannic acid to it.
Heat the solution. On heating a clear solution of tannic acid is
obtained.
Preparation of dye solution: Take about 1.0 g of malachite
dye nand add to it 400 ml of .water. On warming a clear
solution of the dye results ..
Dyeing of wool; Take about 200 ml of dye solution and dip in
it the woollen cloth to be dyed. Boil the solution for
about 2 minutes. After that remove the cloth and wash it
with hot water.3-4 times, squeeze and keep it for drying.
Dyeing of cotton:
Cotton does not absorb malachite green readily, therefore it
requires the use of mordant. For dyeing a cotton cloth dip it in
sodium carbonate solution for about 10 minutes and then rinse
with water. Then put the cloth in hot tannic acid solution for
about 5 minutes. Now take out the cloth form tannic acid solution
and keep it in tartar emetic solution for about 5 minutes. Remove the
cloth and squeeze it with spatula to remove most of the solution.
32
Now place the cloth in boiling solution of the dye for about 2
minutes. Remove and wash the dyed cloth thoroughly with
water, squeeze and keep it for drying.
Dyeing of cotton directly: Take another piece of cotton
cloth and put it directly into boiling solution of the dye.
Keep it dipped for about 2 minutes. Remove the cloth, wash
with water, squeeze and keep it for drying.

OBSERVATION:
The colour of the wool cloth dyed directly by dipping in
hot solution of malachite green dye is fast.
The colour of cotton cloth dyed directly (without using
mordant) by dipping in hot solution of malachite green
is not fast to washing and is of low intensity.
The colour of cotton cloth dyed by using mordant and then
by dipping in hot solution of malachite green is fast to
washing and is of high intensity.

CONCLUSION:
Wool absorbs the dye colour well.
Use of mordant helps in giving fast colour to cotton cloth.

33