2. Basic Textile Terms
and Definition
Some frequently used
terms in textile dyeing
are discussed in this
Section
3. Dyeing
Dyeing is the application of dyes or pigments on textile
materials such as fibers, yarns, and fabrics with the goal
of achieving color with desired color fastness. Dyeing is
normally done in a special solution containing dyes and
particular chemical material. Dye molecules are fixed to
the fiber by absorption, diffusion, or bonding with
temperature and time being key controlling factors. The
bond between dye molecule and fiber may be strong or
weak, depending on the dye used. Dyeing and printing
are different applications; in printing, color is applied to
a localized area with desired patterns. In dyeing, it is
applied to the entire textile.
4. Pigment
Pigment is a type of colour material,
which has chromophore group. There
are different chromophores, i.e. -
N=O, -N=N- etc. Chromophores can
absorb light of some wavelength and
reflect some hence give us a sense of
coloration. Pigments are water
insoluble. They are typically used
with binders in printing or mass
coloration of synthetic fibers.
5. Dyestuff
In dyestuff, there are chromophore groups too. Dye stuff is a type
of unsaturated complex compound. Characteristics of dye stuff are
-
• It must have the chromophore group.
• This chromophore group may be different, i.e. -N=O, -NO2, -NH2 , =CO etc.
• It must be soluble in water and produce saturated solution.
• It must be substantive so that dye stuff can have the ability to enter into the
from dye bath.
• It must have the fastness property,
6. Classification
of Dyestuff
No Single Class of Dyestuff can dye
all type of fibre.
A specific class of dyestuff can
only applied to a given class of
fibres.
Type of dye
stuff
Fibre to apply
Direct Cotton, viscous
Acid Wool, nylon, silk
Reactive Cotton, viscous, wool, nylon, silk
Vat Cotton, viscous, wool, silk
Basic Jute, acrylic
Disperse Nylon, polyester, acrylic, diacetate
triacetate
Sulphur Cotton, viscous
Pigment Cotton, manmade fibre
Mordant Cotton, wool, silk
Mineral Cotton, wool, silk
7. Dyeing
Assistants
Dyeing assistance
a. Electrolytes: NaCl is an important electrolyte in
dyeing with direct dye. It increases absorptivity of
the cotton.
b. Levelling agent: Retarding agent NarSO4 Used as
levelling agent for dyeing wool.
c. Carriers: Rate of dyeing is excellent for using
carrier in dyeing with disperse dye.
d. Solvents: Adding different solvents in dye bath
increases dye uptake .i.e.; benzyl alcohol or urea
is used for dyeing wool in room temperature.
In the whole dyeing
process apart from the
dyestuff and pigments
several other chemicals
are required. They are
commonly termed as
‘Dyeing Assistants’
8. Type of Dyes Various classes and types of
dyes are discussed in this
section
9. Vat Dyes
A classification of dyes that are converted from a
water-insoluble pigment form to a soluble leuco
form applied by immersion to fabric, then
converted back to the insoluble form. The name
comes from "vatting" which once meant using
natural fermentation processes in a vat to
produce the reducing conditions to make the
dye soluble
Dye
class
General Description Application
Vat Difficult to apply. Requires
reduction treatment to
make soluble in water &
oxidation to resume
insoluble state after
dyeing.
One of the most expensive
dye.
incomplete colour range.
Strong in blue &
green but weak in red.
Great all round fastness
except indigo &
sulphurised vat species.
Tending to decrease in
popularity due to
increasing
use of reactive dyes.
Commonly used
for high quality
cotton goods,
e.g. towel;
specially used in
the dyeing of
denim fabric.
10. Working
principle of
Vat Dyes
Vat dyes characteristically require a reducing agent to solubilize
them. The most common reducing agent is sodium dithionite
(Na2S2O4), which converts the dye to its "leuco" form that is
soluble. Once attached to the fabric, the leuco dye is then
oxidized to the insoluble state which is intensely colored.
Chemical reactions such as oxidation, reduction, pH control are
often necessary
11. Reactive
Dyes
Reactive dye attaches to the fibre
by forming a covalent bond. Also
called fibre reactive dye. Reactive
dyes are known for their bright
colours and very good to excellent
light and wash fastness, though
poor resistance to chlorine bleach.
There are several broad classes of
reactive dyes. Most are intended
for cellulose fibres, but some are
intended specifically for wool.
DYE
CLASS
GENERAL
DESCRIPTION
APPLICATION
Reactive Easy application.
moderate price.
complete colour range.
good fastness due to
direct reaction with
fibres.
Commonly used for all
cellulosic goods
especially in knitted
fabric batchwise
dyeing; selective dyes can
also be applied on wool,
silk & rayon.
increasingly used in
printing due to good
fastness.
12. Working principle of
Reactive Dyes
Here the dye contains a reactive group and this reactive group
makes covalent bond with the fibre polymer and act as an
integral part of fibre .This covalent bond is formed between the
dye molecules and the terminal –OH (hydroxyl) group cellulosic
fibres or between the dye molecules and the terminal amino (-
NH2) group of polyamide fibres.
13. Azoic Dyes
"Azo" refers to a chemical compound which contains two
nitrogen atoms with a double bond between them (-
N=N-). "Azo" is use for a class of dyes based on (this)
chemical structure. Azo dyes may be found among direct,
acid, basic, reactive and disperse dye classes. Normally it
is dyed in cold for all natural fibers. Azoic dyes are not
sold in the form of a finished dye but in form of their
components (Insoluble azo base & fast colour coupling
compound) which combine on the fibre to produce a
water insoluble azo dye of exceptional fastness
properties.
Dye
class
General Description Application
Azoic Complicated application.
Limited colour range (red,
orange, navy among the best).
Bright shade at
moderate cost.
Generally good wet
fastness but moderate to poor
on dry cleaning & rubbing
fastness.
Also called naphthol dye due to
the use of naphthol or ice
colour because of the usage of
ice during Application .
Mainly
applied
on cellulosic
fibres,
especially on
brilliant red
shade.
14. Working principle of Azoic
Dyes
Azoic dyes are actually chemically synthesized inside the fibre, and
are not truly dyes, but insoluble pigments. The soluble "naphthol"
component applied to the fibre, and then a solution of "diazo salt"
is used to develop the color. These dyes are used commercially
especially for reds, but are not readily available for dyeing it needs
to be synthesized inside the fibre. The components used can be
very toxic before they react to form the pigment. The
formation of this insoluble dye within the fabric makes it very fast
to washing. The deposition of the dye on the surface of the fibre
produces poor rub fastness but once the loose dyes are removed
by boiling the fabric in soap the dyeing becomes one of the fastest
and long lasting.
15. Acid Dyes
Acid dyes are large class of dyes that applied from acidic
solutions to polyamide fibres, these synthetic dyes are
used for wool, silk and nylon. There are a great many acid
dyes, in a number of major sub-groups, with a wide
variety of properties. Included are "wash fast acid dyes".
"milling dyes". "super milling dyes", "leveling acid, dves",
"1:1 premetallized dyes". "2:1 premetallized dyes" and
others (the premetallized dves are sometimes regarded
as being in a class of their own, apart from acid dyes).
The distinction between some of the groups is often
vague, Acid dyes range from poor to excellent colour
fastness and from dull tones to brilliant shades.
Dye
class
General
Description
Application
Acid Easy
application.
complete
colour
range with
very
good bright
shades.
fastness
properties
may vary
among
individual
dyes.
Commonly
used for wool,
silk & nylon.
16. Working principle of Acid
Dyes
They typically applied in a bath that may range from strongly
acidic to neutral and usually at temperatures approaching
boiling. Bonding between the dye and fiber can be complex.
Some form ionic bonds between basic groups of the fiber and
acid groups of the dye occurs. The family of acid dye is very
large & diverse, varying widely in their methods of dyeing,
application & end use of the dyed fabric.
17. Sulphur Dyes
These dyes are derived from the
formulation of compounds containing
Sulphur. These are water insoluble dyes
and applied by exhaust dyeing method.
Sulphur dyes are widely used for cellulosic
fibres for darker shades. The exact
chemical structure of sulfer dyes is not
known, but these dyes contain sulfur as an
integral of the chromophore as well as in
the polysulphide side chains. These are
produced by thionisation or sulphurisation
of organic intermediates containing nitro
and amino groups.
Dye
class
General Description Application
Sulphur Difficult to apply. Application
similar to vat dyes.
Cheap.
particularly for dark shade.
Incomplete black, navy, khaki
colour range (strong in brown
but
no bright shade).
Poor washing & rubbing
fastness & sensitive to
Chlorine.
May cause fabric rendering of
cellulose upon storage (aging).
Mostly used for
heavy cellulosic
goods in dark
shades.
18. Working
principle of
Sulphur
Dyes
Dyeing includes a few stages. Reduction, dyeing, washing, oxidation, soaping and final
washing. The anion is developed on reducing and solubilizing at boil when it shows affinity
for cellulose. Sodium sulphide (Na2S), the reducing cum solubilizing agent perform both
reduction and solubilization producing thiols and then to sodium salt of thiols or thiolates,
which are soluble in water and substantive towards cellulose. Higher rate of exhaustion
occurs at 90-950C in presence of electrolyte. Dyed cellulosics exhibit tendering effect on
storage under humid atmosphere due to presence of excess free sulphur and aftertreatment
with sodium acetate is required to suppress that. H2S liberated during dyeing forms corrosive
metal sulphide and this restricts use of metal vessels except those made of stainless s. The
exact chemical structure of sulfer dyes is not known, but these dyes contain sulfur as an
integral of the chromophoreteel.
19. Metal
Complex
Dyes
Metal complex dyes or metallized
dyes are that in which typically one
or two dye molecules form a close
permanent association or complex
with a metal atom. The metal
associated with the dye is held by
what is more than one part of the
dye molecule for the electrons of
the metal atom. The metal is often
copper, chromium or cobalt.
Dye
class
General Application
Metal
Complex
Relatively difficult to
apply.
Expensive.
Complete colour range
but duller shade than acid
dyes. Good fastness due
to high molecular size &
metal complex structure.
Mainly used
for wool &
Nylon..
20. Description of Metal Complex Dyes
Metal-complex dyes are synthesized through coordination of bi- or
polyvalent transition metal ions with selective acid dyes. They are
mainly applied to wool, silk and nylon to achieve better wash fastness
for dyed fabrics, compared to those obtained with the parent acid dye.
These dyes may be produced on the substrate, during dyeing, through a
one- or two-step process, which is known as mordant dye. Alternatively
the metal is chelated in the dye structure by the manufacturer before
application, which is called premetallised dye. Overall increase in the
size of the acid dye molecules after coordination with metal is at the
root of improved wash fastness. The extent of exhaustion, diffusion and
levelling through migration, is utilized to promote build-up of shade.
21. Basic dyes
Basic dyes are also known as cationic dyes. This
a class of synthetic dyes, that act as bases and
when made soluble in water, they form a
colored cationic salt, which can react with the
anionic sites on the surface of the substrate. The
basic dyes produce bright shades with high
tinctorial values, on textile materials
Dye class General
Description
Application
Basic
(Cationic)
Careful
application
required to
prevent
unlevel dyeing
& adverse
effect in hand-
feel.
Complete
colour range
with very good
brilliant
shades. .
Mainly used
for
acrylic.
22. Working Process of Basic Dyes
Basic Dyes are cationic soluble salts of coloured bases. These dyes are
applied to substrate with anionic character where electrostatic
attractions are formed. They react on the basic side of the isoelectric
points. Usually acetic acid is added to the dyebath to help the take up of
the dye onto the fibre. . These dyes are mainly applied to acrylic fibers.
The most common anionic group attached to acrylic polymers is the
sulphonate group, -SO3-, closely followed by the carboxylate group, -
CO2-. These are either introduced as a result of co-polymerization, or as
the residues of anionic polymerization inhibitors. It is this anionic
property which makes acrylics suitable for dyeing with cationic dyes,
since there will be a strong ionic interaction between dye and polymer.
Basic Orange 5
23. Disperse Dyes
A class of slightly water-soluble dyes originally
introduced for dyeing polyester, acetate, and related
hydrophobic fibers and usually applied from fine aqueous
suspensions. The negative charge on the surface of
hydrophobic fibers like polyester can not be reduced by
any means, so non-ionic dyes like disperse dyes are used
which are not influenced by that surface charge. The dye
has derived its name for its insoluble aqueous properties
and the need to apply it from an aqueous dispersion. Of
all the dyes, they are of the smallest molecular size.
Dye
class
General Application
Disperse Requires skill in
application
(either by carrier or
under high
temperature).
Moderate price.
Complete colour range.
Limited solubility in
water (normally
dispersed in water for
application).
Good fastness after
reduction clearing
treatment; Posseses
sublimation property.
Mostly used
for polyester
& acetate.
Can also be
applied on
nylon &
Acrylic.
24. Working
Process of
Disperse Dyes
Disperse dye have low
solubility in water, typically
less than 1 mg/L. They are
applied to the article as an
extremely fine suspension.
Upon attachment to the
article, the particles dissolve
and, owing to their low
molecular weight, migrate
throughout.
25. Direct dye
Direct dye is a dye class based on application method,
which is essentially by immersion of the fibre in a
solution of dye without the need for other chemicals to
adhere to the fabric molecules (though other chemicals
may aid exhaustion). Direct dyes have high substantivity,
but bond weakly to fibers, and therefore usually have
poor wash fastness. Light fastness varies from poor to
very good. A post-dyeing fixative is often used to improve
wash fastness. Brightness can be limited in direct dyes,
because brightness often is associated with small
molecules and small molecules tend to make poor direct
dyes.
Dye
class
General
Description
Application
Direct Simple
application.
Cheap.
Complete colour
range.
Moderate colour
fastness but can
be improved by
cationic
aftertreatment.
Mainly used
for cellulosic
fibres.
Can also be
applied on
rayon, silk &
wool.
26. Working Process of Direct
Dyes
The dyeing process with direct dyes is very simple, Direct dyeing is normally
carried out in a neutral or slight alkaline dyebath, at or near boiling point ,
but a separate aftertreatment such as cationic dye fixing , to enhance wet
fastness has been necessary for most direct dyeing . An addition of alkali,
usually sodium carbonate, may be made with acid-sensitive direct dyes and
with hard water as well as to enhance the dye solubilization. When cellulose
is immersed in a solution of a direct dye it absorbs dye from the solution
until equilibrium is attained, and at this stage most of the dye is taken up by
the fiber. The rate of absorption and equilibrium exhaustion vary from dye
to dye. Direct dyes are used on cotton, paper, leather, wool, silk and nylon.
They are also used as pH indicators and as biological stains.
28. Liquor Ratio
liquor ratio influences the dye solubility and the strength
of the electrolyte effect. Lower liquor ratios are
employed whenever possible, for ecological, economic,
and technical reasons. However the correct liquor ratio
for the recipe must be maintained otherwise the right
shade will not be achieved first time
29. Electrolytes
The electrolyte (i.e., sodium chloride or sodium sulfate),
its concentration, and the speed of addition, control the
adsorptive behavior of the dyes and the degree of
exhaustion. A high electrolyte content of the dye bath
shifts the dyeing equilibrium toward the fiber.
30. pH
The pH value influences solubility substantively of the
dyes, and their stability in the dye bath. Lower pH values
improve exhaustion; however, leveling proceeds
preferably at higher pH values.
31. Temperature
Temperature of the dye bath plays vital role for dyeing.
Rise in temperature has a large effect on an increase in
the diffusion rate of dyes into fabrics. Increasing of
temperature increases the rate of dyeing & of the dye
migration. Higher dyeing temperature ensures the good
leveling & better penetration of dye in to the fibers. But
the temperature depends on the types of dye adapted in
the dye bath. For Example-in case of hot brand dyestuff
the dosing temperature of dye is 80ºC and for cold brand
dye temperature is kept 60ºC.
32. Run Time
The time for dyeing also the vital one. A specific Time
adjusted with the temperature, very much needed for
better dyeing. For this reason color dosing takes place in
20 minutes (may vary process to process) & Specific run
time is set for dyeing.
34. Successive
Stage in the
Dyeing
The dyeing process is essentially a distribution process. The dye
is distributed over at least two-phase systems, the dye bath and
textile materials. The stages of dyeing are :
(i) Dye dispersed in the dye bath
(ii) Dye in the diffusion layer(boundary layer)
(iii) Dye in the electrical double layer
(iv) Dye absorbed on the fiber surface
(v) Dye diffused in the fiber
(vi) Dye physically or chemically bond in the fiber
35. 1. Dye
Dispersed in
the Dye Bath
As we seen from the classification of dyes section , most
of the dyes in solution are in molecular and partially
ionized state or exist in the form of ionic micelles.
36. 2. Dye in the
Diffusion
Layer
When a substrate is brought into a dye bath, a
concentration gradient is created which will-make the
dye molecules move or diffuse to the fiber. The dye
which approaches the fiber surface must eventually
diffuse through a thin liquid layer, the so-called diffusion
layer, towards or onto the fiber surface.
37. 3. Dye in the
Electrical
Double Layer
All textile fibers when immersed in water or aqueous
solution, acquire an electrical potential after referred to
as Beta potential. At the fiber surface the dye molecules
must pass the electrical double layer, consists of non-
solvated anions(mostly) and solvated cat ions. These
positive and negative ions try to approach the fiber
surface as close as possible. This layer is about 1nm thin.
38. 4. Dye
Absorbed on
the Fiber
Surface
The dye molecules reach the fiber surface ( and the first
layer of the fiber ). This dye take-up at the fiber surface
(absorption) occurs very rapidly and leads to a reduction
of dye molecules in the immediate vicinity of this
surface.
39. 5. Dye
Diffused in
the Fiber
After absorption, dye diffused in the fiber. Owing to the
high temperature , there is always an abundance of dye
stuff molecules in the vicinity of the fiber and agitation
has little effect upon the time of half dyeing.
40. 6. Dye
Physically or
Chemically
Bond in the
Fiber
The last step of dyeing is fixation. In case of reactive
dyes, the fixation is one-way. Because here dye
molecules become attached to the fiber polymer by
strong co-valent bonds. In case of all other dyes this
fixation is two ways. Because they are fixed with fiber by
weak hydrogen or salt linkage.
41. The following
factors are
responsible for
the anchoring of
the dye molecules
to the fiber
1.Salt linkage/ionic bonds for protein fibers.
2.Co-ordination linkage
3.Hydrogen bonds
4.Co-valent bonds ; for cellulose fibers
5.Physical forces
6.Dispersion forces.
44. Lab Process
Here in the lab a spectrophotometer is used to analyze the
color required for a certain fabric. Then lab technicians come
up with a recipe for obtaining that color by mixing the
available colors. This recipe is then tested in small scale and
adjusted until a satisfactory result is obtained.
45. Floor Process
The recipe that is obtained from the lab is transformed into
bulk recipe keeping the same ratio and adjusting for the
weight of the fabric to be dyed. Dyeing machines are used to
carry out large scale dyeing of fabric and yarn.
49. Chemicals Used
in Dyeing Process
Some commonly used
chemicals in Dyeing
Process are discussed in
this Section
50. Basic
Chemicals
These are the go to chemicals for any dyeing process.
Soda ash (Sodium Carbonate).
Hydrochloric Acid.
Hydrogen peroxide.
Sulphuric Acid.
Acetic Acid.
Caustic soda (NaOH).
51. Acids
Many acids are used in dyeing. Basically for pH control. They
include acetic acid, citric acid, formic acid, hydrochloric acid and
sulfuric acid.
Acetic acid - Acetic acid is used in many dyeing processes. It is
much less expensive than vinegar where large amounts are
required. Often a 58% solution in water is called for.
Citric acid - a solid organic acid; HOCCOOH(CH2COOH)2 , Citric
is sometimes used in dyeing as an alternative to acetic acid. It is
convenient to store and handle, but may be more expensive. It is
a weak acid but can produce pH in the range of 3 to 6
Sulfuric acid – H2SO4 a very potent inorganic ("mineral") acid; a
strong acid. Sulfuric acid is used in some preparation and dyeing
process, most often with wool. Sodium bisulphate (not
bisulphite) can sometimes be used as an alternative
52. Thickener
"Sodium alginate" is used to thicken dye solutions for direct
application. It is a preferred thickener for reactive dyes
because it does not react with the dye. It comes in a number
of variations that have somewhat different properties. "Low
viscosity" types are appropriate for reducing migration of
wet dye solutions for fine line work, while "high viscosity is
more suitable for making printing pastes. It is extracted for
seaweed. Sodium Alginate
53. Chelating
Ageng
Chelating agents are mostly used in dye baths, as they remove the hardness of
water by bonding with heavy metal ion. Chelating agents form a stable
complex compound that does not decompose over a prolonged processing
period. The coordination of water with metal ions enhances the acidity of the
dye solution, which is dependent on the physical and chemical characteristics
of the metal ions. Inorganic chelating agents are also used as detergent by
suspending and dispersing agents. They require less than the stoichiometric
quantity predicted to keep ions in solution (threshold effect). EDTA and NTA
are two of the widely used chelating agent.
54. Dispersing
Agents
Disperse dyes are nonionic chemicals that are barely soluble in water and often crystallize with
varying particle size. These characteristics are inadequate for dispersing dyes of water and
cause unleveled dyeing. To achieve the required particle size and distribution, the disperse dye
is milled, usually in the presence of a dispersing agent. Generally, the dispersing agents are
anionic, e.g., ligninsulfonates, or polycondensates of arylsulfonic acids with formaldehyde,
which facilitate milling. Dispersing agents have shown a dual function role: breaking down
aggregated dye particles and dispersing dyes in the dye liquor. Dispersing agents consists of
high-molecular weight or polymeric compounds in which polar or ionizing groups alternate
with nonpolar groups along the chain. The backbone of a dispersing agent is nonpolar, while
the polar or ionizing groups are located in the side chains. Sodium dinaphthylmethane
Sulfonate and Lingnosulfonates are some widely used dispersing agents.
55. Levelin
g Agent
To achieve uniform dyeing on fabric, it is essential to add a suitable
leveling agent in the dye baths. However, it is quite difficult to explain the
functions and actions of leveling agents. The effects of leveling agents
are: (i) leveling agents tend to decrease the absorption of dyes by forming
a dye-auxiliary complex with free dyes maintaining equilibrium; (ii)
leveling agents act as retarding agents; and (iii) dye migration proceeds
slowly, leads better leading to improved leveling of dye on the fiber.
56. Electrolytes
During dyeing in the dyebath, electrolyte serves as three
important roles—driving dye into textiles causing,
maximum exhaustion of dye molecules through the
presence of salt, and fixing dyestuff to the cellulose
material.
Glauber’s salt is the common name for sodium sulfate
decahydrates Na2SO4. 10H2O; it occurs as white or
colorless monoclinic crystals along with common salt (
NaCl) these are the most commonly used electrolyte in
the dyeing industry
57. Surfactants
Surfactant molecules should have surface active
properties with the chemical structure of a hydrophilic
(water loving) and hydrophobic (having little attraction
for organic molecules) balance. These molecules get
preferentially oriented at the interface between air
and water, which lowers the surface tension of water
substantially when dissolved in the concentration
range of 0.1–10 g/l. Examples are alkyl benzene
sulfonate and sodium lauryl sulfate
58. Anti
Foaming
Agents
The dyeing process can lead to the formation of macro and micro
foams during circulation of dyes and auxiliaries in the dye bath. A
macro foam is displayed with large bubbles, which are visible on
the surface of the system and produce cosmetic imperfections. A
typical list of anti-foaming agents is as follows: 2-ethyl hexanol
(EH), tributyl phosphate (TBP), poly (dimethyl siloxane) (PDMS)
amides, mineral oil, fatty acids, and their derivatives.
59. Reducing
Agent
Beginning of the nineteenth century, sodium dithionate
(Na2S2O4) was introduced as a reducing agent for the vat dyeing
process. Effective sodium dithionate, also called hydrose is till
this date the most used reducing agent in dyeing industry.
60. Softeners A softener is a chemical used to make the touch of fabric more
pleasing. Softened fabrics are fluffier and have better drape
ability. In addition to aesthetics, softeners improve abrasion
resistance, improve tearing strength, and reduce needle cutting
when the garments are sewn. Softeners are divided into three
major chemical categories: anionic, cationic, and nonionic.
Silicon based non ionic softener
61. Anti
Creasing
Agents
Crease is formed in cotton fiber because of the intermolecular
hydrogen bonding of primary and secondary hydroxyl groups of the
polymer chains. The amorphous regions of the hydrogen bonds can
easily break down by folding. In the folding state, the broken
hydrogen bonds stabilize. Different durable press finishes have been
used for many years for use in cotton fabric. N-methylol compounds
such as dihydroxyethylene urea react readily with the hydroxyl
groups of cellulose chains hence acting as anti creasing agent.
62. Bleaching
Agent
Hydrogen peroxide is extensively used in commercial bleaching of
textiles, especially cellulose fibres and wool. It is effective and
non-polluting. A 35-75% solution of H2O2 is used .
63. Others
Diluents : Sodium sulphate is a common diluent for dry dyes.
Fixative : Chemicals that help improve wash fastness of dyed fabric.
Lubricant : A material used to reduce friction between surfaces. Lubricants are often applied to
yarns that are used for knitted fabrics such as jersey. They help protect the yarn from damage
and the machinery from wear.
Enzyme :. Enzymes are now extensively used in textile processing. Amylase enzymes are used for
desizing, and cellulose enzymes are used for modification of cellulosic fabrics such as de-pilling or
or permanent softening.
Binder : A material that is typically used to attach a pigment to fabric.
Antichlor : A chemical used to neutralize chlorine bleach.
Anti Migrant : An additive used in dye or pigment mixtures to prevent undesired movement or
spreading of the wet dye on fabric
Restraining Agent :A dye bath auxiliary that is typically used to prevent one fibre in a blend from
taking up dye intended for the other fibre, or to equalize the uptake.
65. Summing-up
In this presentation I tried to discuss
the dyeing process and other
variables related with it along with its
components as concisely as possible.
The knowledge of Textile dyeing I
gained from my industrial project at
Sanzi Textile Mills Ltd was the key
factor in preparing this presentation.
