Chemistry

Investigatory Project
On Dyeing Of Fabrics
 Certificate
It is hereby to certify that, the original and genuine
investigation work been carried out to investigate
about the subject matter and the related data
collection and investigation has completed solely,
sincerely and satisfy by R. Muthu Saravanan of
class 12th Sri Vetri Vidhyalaya Public School,
regarding his project titled Project on Dyeing of
Fabrics.

Viva voce held on :

Registration no :
Signature of Guide:

Signature of internal
Examiner:
 Acknowledgement
I would like to express a deep sense of thanks and
gratitude to my chemistry teacher
Mrs. M . Fathima Begum and for guiding me
immensely through the course of my project. Their
constructive advice and constant motivation have
been responsible for the successful completion of
my project.
My sincere thanks to my parents for their
motivation and support. I must thank my classmates
for their timely help and support for compilation of
this project.
 Contents

 Introduction
 Objective
 Requirements
 Procedure
 Conclusion
 Bibliography
 INTRODUCTION

Dyes are coloured substances which can adhere to

the surface of materials and are used to give colour
to paper, foodstuffs, and various textiles such as
cotton, wool, synthetic fibres, silk etc. For example,
alizarin, indigo, congo red, etc. Chemically, a dye
contains:
 Some group (such as azo, indigoid,
triphenylmethyl, anthraquinone, etc.) which
is responsible for the colour of the dye.
 Some groups (such as –NH2, -SO3H, -COOH,
etc) which makes the dye stick to the fabric
by formation of some salt.
Dyeing is the process of adding colour to textile
products like fibres, yarn and fabrics. The
temperature and time controlling are two key
factors in dyeing.
The primary source of dye, historically has been
nature, with the dyes being extracted from plants
and animals. Since the 18th century, humans
produced artificial dyes to achieve a broader range
of colours and to render the dyes more stable to
resist washing and general use.
The dyed fabrics appear to be coloured because a
particular dye absorbs radiations of some specific
wavelengths from the visible region of
electromagnetic radiations which fall on the
surface. The remaining radiations (complementary
colours) of light are reflected. The colour which we
observe is due to the reflected light. For example, if
a dye absorbs the light in the wavelength region
corresponding to red, then it would appear green,
which is the complementary colour of red.
Similarly, if a dye absorbs blue colour, it would
appear orange.

Methods to apply dye

Dyes are applied to textile goods by dyeing from
dye solutions and by printing from dye pastes.
Methods include:
 Direct application
 Yarn dyeing

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, drycleaning solvents, light
and dilute acids.

Types of dye
The dyes are classified by dye manufacturers for
marketing into the following types:
 Acid dyes: These are azo dyes and are
characterized by the presence of acidic groups.
The presence of soluble and serves as the
reactive points for fixing the dye to the fibre.
 They are chiefly used for dyeing wool, silk
and nylon. For example, Orange I and Orange
II.
 Basic dyes: These dyes contain NH2 or NR2. In
acidic solutions, these form water soluble
cations and use the anionic sites on the fabric
to
get used for dyeing wool, silk and nylon. For
example, aniline yellow, butter yellow.
 Direct dyes: These are also azo dyes and are
used to dye fabrics directly by placing in
aqueous solution of the dye. These dyes attach
to the fabrics by means of hydrogen bonding.
 Disperse dyes: These dyes are applied in the
form of dispersion of minute particles of the
dye in a soap solution in the presence of
phenol or benzoic acid. These dyes are used to
dye rayons, Dacron, nylon, polyesters etc. For
 example, celliton fast pink B and celliton fast
blue B.
 Fiberactive dyes: These dyes are linked to the
fibre by –OH or –NH2 group present on the
fibre. These dyes induce fast colour on fabrics
which is retained for a longer time. These dyes
are used for dyeing cotton, wool and silk.
 Insoluble dyes: These dyes are directly
synthesized on the fibre. The fabric to be
coloured is soaked in an alkaline solution of
phenol and then treated with a solution of
diazotized amine to produce azo dye. The
colour induced by such dyes is not so fast.
These dyes are used for dyeing of cotton, silk,
polyester nylon, etc. For example, nitroaniline
red.
 Vat dyes: These dyes are water insoluble and
before dyeing these are reduced to colourless
compounds in wooden vats by alkaline
 reducing agents. The fibre is then soaked in
the solution of the dye. Fibre is then exposed
to air or an oxidizing agent. By doing so the
colourless compound gets reoxidized to
coloured dye on the fabric. For example,
indigo.
 Mordant dyes: These dyes are applied after
treating the fabric with precipitates of certain
substances (mordant material) which then
combines with the dye to form a coloured
complex called lake. Some of the mordants are
salts of aluminium, iron and tannic acids.
Depending on the mordant used, the same
mordant dye can give different colours and
shades. For example, alizarin gives red colour
with aluminium and black violet with iron
mordant. Mordant dyes are used for dyeing of
wool, silk and cotton.
 OBJECTIVE
 To dye wool and cotton with malachite green.

REQUIREMENTS
500 ml beakers, tripod stand, wire gauze, glass rod,
spatula, wool cloth and cotton cloth.
Chemicals required: Sodium carbonate, tannic acid,
tartaremetic acid, 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 tartaremetic solution: Take
about 0.2 g of tartaremetic and dissolve it in
100 ml of water by stirring with the help of
glass rod.
 Preparation of tannic 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 0.1 g
of malachite green dye and add to it 4oo ml of
 water. On warming a clear solution of the dye
results.
 Dyeing of wool: Take about 200 ml of dye
solution and dip it in the woolen 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 a 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 from tannic
acid solution and keep it in tartaremetic
solution for about 5 minutes. Remove the cloth
and squeeze it with spatula to remove most of
the solution. 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 pit 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.
Compare the colour of this cloth with that dyed
by using mordant.

OBSERVATIONS
 The colour of wool cloth dyed directly by
dipping in hot solution of malachite green
dye is fast.
 The colour of cotton dyed cloth directly
(without using mordant) by dipping in hot
solution of malachite green is not so fast to
washing and is of low intensity.
 The colour of cotton cloth dyed indirectly
by using mordant and then by dipping in
hot solution of malachite green is fast to
washing and is of high intensity.
BIBLIOGRAPHY
 www.wikipedia.com
 www.chemistry.com
 www.wikihow.com