denim washing (thesis)
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Final Year Thesis Denim Washing
Indus Institute Of Higher Education
1
INDUS INSTITUTE OF HIGHER EDUCATION
KARACHI
THE STUDY OF DENIM WASHING
A PROJECT SUBMITTED TO
THE FACULITY OF TEXTILE SCIENCES
IN PARTIAL FULFILMENT OF REQUIRMENTS FOR
DEGREE OF
BACHELOR OF TEXTILE SCIENCE
(B S TEXTILE)
SUPERVISED BY:
ENGR ABDUL SALAM
FACULTY MEMBER.
Email: engrabdulsalam@hotmail.com
SUBMITTED BY:
SYED ASIM NAJAM
UMAIR MAJEED KHAN
MAY, 2010
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ACKNOWLEDGMENTS
All thanks are due to Almighty “ALLAH” the most beneficial and merciful who enabled
us to complete this project.
The completion of this project is perceived as the fruitful result of and incredible effort,
devotion and hard work. It can be stated without any hesitation that this thesis is the
outcome of the joint effort of all concerned by successfully negotiating the various
tedious problems and hurdles.
We are particularly thankful of Sir Adbul Salam our project advisor for the guidance and
valuable cooperation render by him at any stage regarding this project. He fully indulged
himself to facilitate our job whenever approached him to seek guidance regarding this
study.
Special thanks are reserved for the Head of Textile Science Department Sir Hasib-u-
Salam for encouraging and motivating throughout the successful completion of this
project. We are very thankful to each and every person of Ragby Industries specially Sir
Ejaz Shah, who make ourselves very comfortable during our whole internship program,
who led us to complete this project work.
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Faculty of Textile Science
INDUS INSTITUTE OF HIGHER EDUCATION
Karachi.
Certificate
I am pleased to certify that the following students have
satisfactorily carried out a thesis work, under my supervision on
the topic of “ Denim Washing ”
I further certify that his thesis is worthy of presentation to the
Faculty of Textile Sciences, INDUS INSTITUTE OF HIGHER
EDUCATION
Karachi for the degree of Bachelor of Science in Textile.
1. Syed Asim Najam
2. Umair Majeed Khan
HOD Textile Science: __________________
External Examiner: __________________
Supervisor: ___________________
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TABLE OF CONTENT
Content Page No.
Chapter 11.1 Introduction 7
1.2 Back ground 7
1.3 History of denim 7
1.3Literature Review 9
1.4 Area of study 10
1.5 Expected Results
Chapter 2 Warping
2.1 Introduction 11
2.2 Ball warping 11
2.3 Beam warping 12
2.4 Components of machine 12
2.5 Procedure of warping 13
Chapter 3 Dyeing
3.1 Introduction 14
3.2 Classification of dyes 14
3.2.1 Direct dyes 14
3.2.2 Reactive Dyes 15
3.2.3 Sulphur Dyes 15
3.2.4 Vat dyes 16
3.3 Denim dyeing 18
3.3.1 Rope dyeing 20
3.3.2 Slasher dyeing 21
3.4 Difference between rope dyeing and slasher dyeing 24
3.5 Cooking tanks and dsoing system 26
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3.6 After-washing process and drying 27
3.7 Sizing 27
3.8 Drying zone 28
3.9 Accumulator 28
3.10Leasing zone 28
3.11 Expansion comb 29
3.12 Beaming 29
3.13 Transportation of beams 29
Chapter 4 Weaving
4.1 Introduction 30
4.2 Basic weave design 30
4.3 Weaving of denim fabric 31
4.4 Typical denim construction 32
4.5 Non-conventional denim fabric 33
4.6 Shedding system 34
4.6.1 Crank shedding 34
4.6.2 Cam shedding 34
4.6.3 Dobby shedding 35
4.6.4 Jacquard shedding 35
4.7 Classification of weaving machine 36
4.7.1 Shuttle weaving 36
4.7.2 Shuttle less weaving 37
Chapter 5 Faults in production of denim5.1 Faults of warping 41
5.1.1 Faults in machine 41
5.1.2 Faults in raw material 41
5.1.3 Faults in product 41
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5.2 Faults of dyeing 42
5.2.1 Faults in machine 42
5.2.2 Faults in raw material 42
5.3 Sizing Faults 425.4 Weaving Faults 42
Chapter 6: Denim washing
6.1 Introduction 43
6.2 How does washing create unique look 43
6.3 Processes involve in Denim washing 43
6.3.1 Dry process 43
6.3.2 Wet process 47
6.4 Types of denim washes 48
6.4.1 Chemical wash 48
6.4.2 Mechanical wash 56
6.6 Spraying 60
6.7 Whiskering 61
6.8 Softening process 63
6.9 Machine use for denim 67
6.10 New development 69
6.11 Value edition 71
Chapter 7
7.1 Conclusion 74
7.2 Reference 75
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1.1 INTRODUCTION
Denim and jeans - where do the names come from? The word jeans come from a kind of
material that was made in Europe. The material, called jean, was named after sailors from
genoa in Italy, because they wore clothes made from it. The word 'denim' probablycame from the name of a French material, serge de nimes: serge (a kind of material) from
nimes (a town in France),
1.2 BACKGROUND
We have interest in denim washing.
Denim has fewer difficulties in process as compare to other dyeing process.
Few industries work on this topic so that‟s why we decide to do the topic and wewill try to optimize the process and try to invent new washes or finishes in denim.
Denim is a universal fabric, one that covers all age groups, races and social
divides that‟s why we think it will have high demand in the future and this is also
the point of our attraction for this topic.
1.3 HISTROY OF DENIM:
In fashion history, jeans and denim history continues to baffle. No one truly knows the perfect answer to where jeans began. As so often happens fashions often emerge
together in various parts of the world and are the result of the sudden availability of a
new fabric, cloth, dye or technique. But we do know that the phrase denim jeans are
thought to derive from several sources. No one is totally certain where the words come
from. A majority of source books suggest that denim derives from the English
translation of the South of France French phrase 'serge de Nîmes'. Denim fashion
history is thus associated with Serge de Nimes.
When talking about denim the name Levi´ s is one of the first to be mentioned. Levi´ s
which stands for Levi Strauss is normally called the forefather of jeans. When tracing
back the history of these trousers to its origins it is true that Levi Strauss played an
important role concerning their development and distribution but he had also other
inventive business partners.
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Levi Strauss found out that the gold diggers´ hard work in the mines made their clothes
get worn out very quickly and he produced stout working trousers out of the sail cloth he
had taken with him which he called half overalls“. When he continued producing these
trousers he used cheap cotton fabrics coming from Genova. The name of the town of
Genova was modified into jeans” in the American slang. At the end of the sixties of the
19th
century he replaced the brown sail cloth by an indigo-dyed, wear resistant cotton
fabric coming from France. The name of this fabric was Serge de Nimes“. Serge is the
French. Expression for a combined twill and Nimes is the French town where the fabric
comes from. The fabric´s name Serge de Nimes was quickly turned into Denim“ in
American colloquial language. By applying this indigo-dyed combined twill the first
jeans out of Denim was almost born or better sewn. The application of metal rivets for
jeans is due to the Polish emigrant Jacob W. Davis, also called AJacob Youphes.
Although the working trousers out of Denim were stout they had a tendency to get worn
out where the pockets were. Jacob Youphes mended the trousers with a needle and
thread. One day a customer inspired him to repair the torn off pockets with the help of
rivets. Under the management of Levi Strauss the jeans were now produced in series.
Since the trousers were so stout not only the gold diggers liked them but which is not
surprising in America? The cowboys appreciated them very much, too. When the trousers
were applied as working trousers for cowboys, however they got worn out at the crotch
tip. This was no problem for Levi Strauss and Co. since they reinforced the trousers again
with metal rivets at the crossing point of the four seams at the crotch tip.
About 1947 denim made a break-away from work clothing image, chiefly in the area of
sportswear and rainwear and an occasional appearance in high fashion collections as a
"different-looking" evening dress. In 1970 American youth adopted denim as their
favorite fabric. Part of a "back to nature" movement that emphasized ecology and the
natural denim being a fabric created from a natural fiber was a primary factor. Since 1960the jeans business has undergone an explosive transformation, from a source of tough,
cheap clothing for cowboys, blue-collar workers and penniless youth into a fashion
conscious market for a widening mass of people of almost all ages .
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1.4 LITERATURE REVIEW
The studies related to the denim manufacturing and processing is available to understand
the process sequence and achieving various washing effects of denim.
Processes for producing yarns dyed with indigo have been in use for thousands of years.The original batch methods for dyeing yarn skeins have been replaced for the most part
with continuous dye ranges that can produce thousands of pounds of dyed yarns each
hour. Different experiment have been done before on denim washing, denim dyeing they
are done internationally as well as locally in our country in which few are discussed
below.
In past, stone (pebbles) are use for washing which is known as stone wash but
now a days stone (pebbles) are replaced by rubber balls because stone damaged
the fabric during the washing process.
Another experiment was done internationally and primary object of the invention
is to provide a method of treating denim fabric in plain fabric form or in garment
form to economically produce stonewashed denim fabric of various different
shades colors without multiple steps, expensive equipment, or large inventories of
fabrics and dyes. Another object of the invention is to economically provide
stonewashed denim fabric of different shades and colors.
In earlier work many denim washes has been created in which some denim
washed names are given below:
1 ACID WASH
2 ENZYME WASH
3 BLEACH WASH
4 STONE WASH
Companies that “finish” jeans by washing them or distressing them for a worn -in
look. Most major jeans manufacturers use several different laundries that
specialize in different finishes. The main techniques used include simple washing,
stonewashing, which uses an abrasive-bristled Tonello machine, sandblasting,
laser burning, or applying enzymes to simulate “cat‟s whisker”-wear line, and
sandpapering by hand.
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Our seniour students also worked on denim washing and they also tried to
developing the new techniques in denim washing but unfortunately they were not
success in developing new techniques.
1.5 AREAS OF STUDY:
In this project we will study denim washing along with its weaving and its dyeing process
and we will try to optimize the current methods but we will focus deeply on denim
washing and its finishing.
WARPING
The first process in the manufacturing of denim is warping.
2.1 INTRODUCTION
Warping is the process of transferring multiple yarns from individual yarn packages onto
a single package assembly. Normally, yarns are collected in a sheet form where the yarns
lie parallel to each other and in the same plane onto a beam, which is a cylindrical barrelwith side flanges. This is known as beam warping. For ball warp denim, the yarns are
brought together and condensed into a rope before being wound onto a relatively short
cylindrical barrel (sometimes called the shell or log) that has no end flanges.. In both
cases, the supply yarn packages are placed on spindles, which are located in a framework
called a creel.
2.2 Ball Warping :
In ball warping (Figure 5), 250 to 400 yarn ends are pulled from the creel. The yarns then
pass through a comb-like device (sometimes called a hack or reed), which keeps each
warp yarn separate and parallel to its neighboring ends. At intervals of every 1000 or
2000 yards (or meters), a lease string is placed across the sheet of warp yarns to aid yarn
separation for the re- beaming operation, which will occur later. The yarns then go
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through a funnel-shaped device called a trumpet or condenser, which collapses and
condenses the sheet of yarn into rope form. This device is located at the base of the
warper head and traverses back and forth, guiding the newly formed rope of yarn onto a
log. The rope must be wound at a constant tension to keep the yarns from tangling.
2.3 Beam Warping
Beam warping maintains the yarns in an open sheet form and winds the yarns parallel to
each other onto a slightly wider flanged beam. These yarns will not go through the rope
indigo dye range, but are left “natural” and will end up either slasher dyed or in an un-
dyed fabric, which can later be piece dyed, garment dyed, or left natural. Another option
would be to beam dye the yarns using a dye other than indigo.
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2.4 COMPONENTS OF MACHINE
• Creel
• Rods
• Chain System
• Control Devices
• Sensors
• Head stock
• Expansion Comb
• Dust and fly accumulation unit
Showering assembly
2.5 PROCEDURE OF WARPING:
The creel stand has maximum capacity of five cones per stand.
The yarn from the cones is unwounded and passes from rod by cross wound, holed by a
catcher guided to the tensioning zone when cone rotates anticlockwise. There are three
types of tension in warping i.e. catcher tension, rod tension, and sacker tension. Magnetic
tensioner is used for yarn tension.
Then the yarn comes to the winding zone or headstock. Combs straighten the yarns
towards pressure drum, which supports beam, and yarns in an alignment so that each and
every yarn end can wound separately. Static charges due to friction of yarns on metal
surface cause static charges, which are removed through an anti static device. Then the
yarn is wounded on beam in this way for a required length if beam is changed after one
filling of beam then knotting of yarns is made. Similarly if cones are finished on one
frame side then trolley system of cone changing is used in this way chains rotates the
whole frame of empty side and new filled side of frame is forwarded again knotting is
done between the new cones yarn and already winded yarn. Extra yarn is then removed
through cutting. Sensors sense any type of yarn breakage and in case of yarn breakage
knotting is done.
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DYEING
3.1 INTRODUCTION
Dyeing is a process in which we impart colour into the fabric. All commercial textile
dyeing processes take place by the application of a solution or a dispersion of the dyes to
the textile material followed by some type of fixation process. The dye solution or
dispersion is almost always in an aqueous medium. A major objective of the fixation step
is normally to ensure that the coloured textile exhibits satisfactory fastness to subsequent
treatment in aqueous wash liquors. Dyeing is mainly depends on the type of fabric,
structure of fabric and the properties of dyes.
3.2 CLASSIFICATION OF DYES
For our convenience we make classes of dyes, due to these classes the application of dyes
is much easier. The classifications of dyes are as follows:
• Direct Dyes
• Reactive Dyes
• Sulphur Dyes
• Vat Dyes
3.2.1 DIRECT DYES
Direct dyes have been used to dye cellulose for over 100 years. Because of the simplicity
of application and great choice of products available, direct dyes are a popular dye class.
Direct dyes ranges from moderate to poor in wash fastness. Light fastness varies from
poor to excellent depending on the particular dye. Direct dyes depend on secondary
forces such as hydrogen bonds and vander waals forces to bond with cellulose fibres.
Since secondary forces are relatively weak. Therefore, direct dye molecules have
relatively high molecular weights, typically 400 to 1200. The great majority of direct
dyes are azo structures.
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3.2.2 REACTIVE DYES
Reactive dyes contain groups that react with the hydroxyl groups in cellulose. The
reaction between a reactive dye and the fibre produces a covalent bond. By their nature
reactive dyes also react with water. Dye which reacts with the fibre is said to be “fixed”
to the fibre. Dye which reacts with water is said to be “hydrolyzed”.
Fixation Reaction
Cell – CH2 – OH + DYE – X Cell – CH
2 – O – DYE + HX
Cellulose reactive dye dyed fibre acid
X=reactive group
Hydrolysis reaction
H – O – H + DYE – X DYE – OH + HX
Dye molecules which react with the fibre and become fixed have excellent fastness to
washing because of the high strength of the covalent bond. Dye molecules which are
hydrolyzed may be weakly attached to the fibre and if not washed out at the end of the
dye cycle have very poor wash fastness.
3.2.4 SULPHUR DYES
Sulphur dyes are widely used on cotton mainly because they are economical to use. They
have good to excellent wash fastness and good light fastness in dark shades. Light
fastness of pale shades is poor. Sulphur dyes are usually dull in shade since the molecular
structures are complex. As a class, the sulphur dyes are not resistant to chlorine
containing bleaches.
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Chemical nature of sulphur dyes
3.2.5 VAT DYES
Vat dyes are mainly on cellulosic fibres, but some can be applied to protein fibres. Theyusually have outstanding colourfastness properties. Vat dyes are more expensive and
difficult to apply than other classes for cellulose such as directs sulphurs, and reactive.
Indigo is a special case in the vat dye class. Indigo is attractive for its pleasing blue
colour and for the unique fading characteristics of garment dyed with it.
Vat dyes are characterized by the presence of a keto group. Vat dyes in keto form are
water insoluble pigments.
CHEMICAL CONSTITUTION OF VAT DYES
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Reactions of Indigo Dye
THE SUBSTANTIVITY AND DYEING CHARACTERISTICS OF
VAT DYES FOR CELLULOSIC FIBRES.
BASIC STEPS IN THE DYEING PROCESS
The dyeing of cellulosic materials with vat dyes follows a four-step sequence:
1. Preparation of the vat containing the leuco forms of the dyes;
2. Dyeing of the material, in which the fibers absorb the water-soluble leuco
compound;
3. Oxidation of the absorbed leuco compound back to the parent pigment inside the
fibers
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4. Soaping of the dyed material to remove pigment loosely adhering to the fiber
surfaces and to develop the true shade and fastness properties.
3.3 DENIM DYEING:The classical jeans were produced out of indigo-dyed Denim fabric. The special character
of this fabric only the warp thread is dyed makes it necessary to carry out dyeing in yarn
form. The yarns applied for Denim were exclusively produced on ring spinning machines
in former times. The development of OE (open end) yarns by applying smaller rotors
with a spinning speed of up to 200 m/min - has led to the application of OE rotor yarns
both for warp and weft. The yarns applied for weaving must be of high quality: a high
fiber for strength, regularity as well as a small part of short-stapled cotton fibers belong to
the basic features of the denim yarn. For regular jeans qualities the warp yarns are spun in
a fineness of 50 to 90 tex, for the weft yarn the fineness ranges are mainly 75 to 120 tex.
If Denim is made out of Tencel or Modal especially for jeans shirts the finenesses are up
to 25 tex.
Indigo, sulphur and indanthrene are mainly used in the dyeing process. Two methods are
applicable for continuous dyeing with indanthrene dyes: rapid dyeing and vat dyeing.
While processing the basic colored denim, reactive dyes are used and fixed with hot
caustic soda solution. The dyeing process is mainly influenced by the dyestuff
characteristics, dyeing temperature and necessary chemicals used in the process. Indigo
dye is the most popular choice as it has good depth of shade and suitable rubbing and
washing fastness. When cotton yarn is dyed with indigo, it leaves a ring-dyeing effect,
because of which the outer layer of warp yarn is coated with indigo, and the core of the
yarn remains undyed. This gives the denim garment a unique „faded look‟ and a rich blue
shade after repeated use and wash. Originally, the warp yarns or ends were put through
the dye bath side by side to form a sheet of yarn, which passed continuously through
several dye baths, squeeze rollers or airing sequences. However, if there were breaks in
the yarn (and there would be, as each yarn had to take the tension of being pulled through
these processes virtually on its own), the dyeing process had to be stopped. The yarns
would be then mended, or else it would lead to very bad tangling. These stoppages would
in turn cause large shade variations, and the yarn breaks would show up as bad faults in
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the fabric. Now, an infinitely more efficient system has been introduced. Special attention
shall be paid here to Indigo, the king of dyestuffs” since it plays an important role in
obtaining the jeans effect. Indigo belongs to the category of water-insoluble dyestuffs. It
was first mentioned in a book 13 BC; at that time the name Indian blue indicated the
country the color came from. It is said to have been used for dyeing in India and China
2000 years BC already.
The Indigo plant is used for preparing Indigo
Nowadays, yarn dyeing with indigo is done continuously. Here the various dyeing
processes with different concentrations of chemicals as well as the subsequent yarn sizing
exert an influence on the quality and the appearance of the ready fabric. There are two
processes in the practice for continuous dyeing:
• · Rope Dyeing
• · Slasher or Sheet Dyeing
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3.3.1 ROPE DYEING
Indigo Rope Dyeing When dyeing according to the rope dyeing or cable dyeing
method.350 - 400 warp threads are bound on the ball warper to very thick cables of 10
000 - 15 000 m length. On the continuous dyeing installation, 12 to 36 cables are led side
by side, wetted, dyed and dried after the dyeing process on cylinders and put into cans.
Then the cables are dissolved to warps on the long chain beamer. The warps are added to
the sizing machine, sized and then led together to warp depending on the total numbers of
threads. In practice, this method has proven to be very good through obtaining an
optimum indigo dyeing. However it is important that the cables have a constant tension in
order to avoid warp stripes. The disadvantage compared to other methods is that yarn
breakages do occur more often. Size of the dyeing unit is between 60 - 80 m. Normally, 6
dyeing vats are in use. There are nevertheless variations with 3 to 8 dyeing vats.
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3.3.2 SLASHER DYEING
Indigo Sheet or Double Sheet Dyeing (Slasher Dyeing).When dyeing according to the
sheet dyeing method, instead of cables the warp threads are fed to the machine parallel
next to each other. These are much smaller compared to the rope dyeing machines.
Another advantage is that the cables don‟t need to be open after dyeing. Moreover, each
yarn wets much faster and in this way reduces the dipping and wetting times during
dyeing. All in all, each thread has a larger surface compared to a dyeing cable and this
requires somewhat more hydrosulphite to prevent a premature oxidation of the indigo.
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Whereas during rope and sheet dyeing the yarns are always led in succession to the
dyeing baths, the fabric of the loop dye method is led several times through the same
dyeing bath. The machine is then much shorter and the hydrosulphite consumption is
lower. Depending on the number of dyed passages and the concentration of indigo in the
dyeing vats, different dyeings of the yarn. . [3]
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WORKING PRINCIPLE OF SLASHER
Warp beams are brought to the dyeing and sizing section in sheet form as per
requirement. The warp sheet is taken to wetting tank (like mercerize, semi mercerize and
causticize tanks depends upon the dyeing methods) which swells the fiber and increasesits dye uptake. It is then taken to a hot washing tank whose temperature is maintained at
850
C. It is then taken to cold washing tank whose temperature is maintained at 600
C.
Warp sheet is then taken to dyeing tanks where dye is reduced to soluble leuco form by
using sodium hydrosulfite, yarn is then contacted with the reduced dye, and the dye is
adsorbed by the fibers. The fixed leuco indigo in the yarns of the warp sheet was oxidized
to form pigment during transport of the warp sheet in the air space following the dwelling
chamber, taking approximately 60 seconds. It is taken to two hot washing tanks for fixation. Following rinsing, warp sheet is dried on cylinders dryers prior to the
application of sizing agent.
OXIDATION REACTION
Na2S
2O
4+ O
2+ 2NaOH → Na
2SO
4+ Na
2SO
3+ H
2O + C
16H
10O
2 N
2 Na
2+ ½ O
2+ H
2O +
Sodium Hydrosulfide C16
H10
O2 N
2+ 2NaOH
Oxidized indigoDuring the slashing process, the sheet of yarns is passed through the size box which
contains the hot water solution or mixtures of sizing agents. The yarns pick up the
required quantity of size solution in the size box, excess size is squeezed off as the yarns
pass through squeeze rolls. After the size box, the yarns go through the dryer section. The
wet yarns are dried by using drying cylinders. Cylinder drying is done using steam heated
hot rolls. The Teflon coating is done on all the cylinders to prevent sticking of yarns.
Accumulator stores 150 meters of warp sheet. Due to the nature of sizing, the yarns in the
sheet may be stuck together at the exit of the dryer section. They are separated into
individual sheets by leasing rods and individual ends of yarns are separated by passing
through comb then the yarns are wound on to a loom beam for weaving.
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3.4 DIFFERERENCE BETWEEN SLASHER AND ROPE DYEING
ROPE DYEING SLASHER DYEING
Warp yarns are assembled on the ball
warper to form a rope.
Warp yarns are directly wound on a beam
in the form of a sheet.
Ropes are drawn through dyeing range
side by side.
Dyeing is done in sheet form
After dyeing they are dried on a drum
drier and deposited in cans. The ends are
spread out on long chain beamer Or on a
rebeamer, and the yarn sheet is wound
onto warp beams. These beams are then
taken to sizing. After sizing they are dried
and assembled on the weaving beam.
After dyeing the warp sheet is dried on the
same machine in continuous process by
drying cylinders and then sizing is done
on the same machine and after drying it is
wound on a weaver beam
Good depth of shade is achieved Depth of shade is not good
In rope dyeing we have very high
productivity but the limitation is that it is
In Slasher dyeing productivity is less but
it is feasible for short lots.
very expensive for short lots.
It can only run for coarse yarn as the
tension on rope breaks the yarn
It can run for fine yarns too
Time consuming processes are rebeaming
and then sizing
Rebeaming is not required and sizing is
done after dyeing.
As the dye bath is less exposed to air so
dye is affected less.
Setting up or stabilization of the dye baths
is affected faster.
The oxidation time is greater for fixation The immersion and oxidation times are
much shorter
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The wetting time is greater and so dye is
applied uniformly
Owing to the paralleled warp threads, the
wetting process is shorter and a wetting
trough may be adequate.
The rope dyeing machine is much
expensive than Slasher.
The sheet dyeing machine is smaller than
a rope dyeing machine, which means that
the prime costs are lower
Rope opening is avoided Warp sheet entanglement is a danger
Bottoming: In this case another dye is applied before dyeing with indigo.
First the warp sheet is dyed with sulfur and then it is washed and then dyed
with indigo.
Topping: In this case the warp sheet is dyed with indigo in start and then it
is washed and then it is dyed with another dye (normally with sulfur).
Bottoming indigo Topping: In this case the warp sheet is firstly dyed
with some dye and then after washing with indigo and then after washing with
other dye like sulfur.
Washing is done after each bath in order to remove unfixed dye. Dyeing of indigo occurs
at low temperature and that of sulfur at high temperature. Firstly the warp sheet is dipped
in the dyeing liquor and then airing is done in order to do fixation as indigo and sulfur
dyes are in reduced form in liquor than they are oxidized by giving air. Which is
necessary because if airing is not proper than immature oxidation occurs. For this purpose
an airing zone of about 40 m is provided after each bath. The airing process is also known
as dwelling time.
3.5 COOKING TANKS AND DOSING SYSTEM:
A color kitchen is also known as cooking tanks. Five cooking tanks are also provided
with the machine which is used for the preparation of liquor for pre-treatment, dyeing and
sizing. They are connected with the machine via dosing system. The computer-controlled
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dosing system for dyestuff and chemicals is the heart of the machine. Indigo vat,
hydrosulphite and caustic soda are continuously added according to calculated quantity
indications and depending upon speed. Color UN levelness owing to fluctuations in bath
concentrations does no longer occur. Owing to the high circulation rate of the dye liquor
in two circuits, local bath concentration differences are avoided. The metering control
stores the required adjustment parameters and guarantees a high level of process
reliability and reproducibility.
The used dyes can also be preserved with the help of two storage tanks on the machine.
Useless dye is drained easily from the tanks with the pipes connected at there bottom.
3.6 AFTER-WASHING PROCESS AND DRYING
After dyeing of the warp sheet washing is done in order to remove the unfixed liquor
from the warp sheet. The two or three hot washes are done after the dyeing. And then it is
dried on the assembly having 07 drying cylinders.
3.7 SIZING
Although the quality and characteristics of the warp yarns coming out of the winding,
warping and dyeing processes are quite good, they are still not good enough for the
weaving process for most of the yarns. The weaving process requires the warp yarns to be
strong, smooth and elastic or extensible to certain degree. To achieve these properties on
the warp yarns, a protective coating of polymeric film forming agent (size) is applied to
the warp yarns prior to weaving; this process is called slashing or sizing.
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The main purposes of slashing are as follows:
• To increase the strength of the yarns
• To reduce the yarn hairiness that would cause problems in weaving process
• To increase the abrasion resistance of the yarn against other yarns and various
machine elements
• To reduce fluff and fly during the weaving process for high speed weaving
machines.
One sizing tank is provided after the drying zone. The capacity of the size box is about
400 liters. Sizing material is provided automatically by dosing system or it can be
manually added.
3.8 Drying Zone
After the size box the yarns go through the dryer section. The wet yarns are dried by using
cylinder drying. Cylinder drying is done using steam heated hot rolls called the drying
cylinders. The cylinders are coated with Teflon to prevent sticking of the yarns on the
cylinders. The drying zone contains 14 cylinders.
3.9 ACCUMULATOR:
Accumulator is also known as compensators. After drying two accumulators are provided
on the machine. Whose function is to minimize chance of stoppage of machine because
of the change of beam on the head stock and insertion of rods in the leasing zone they
accumulate the extra warp when the speed is reduced from the headstock by moving
assembly to upward direction as shown in figure below
When the head stock is moved with a greater speed the excess warp is removes from the
accumulator.
3.10 LEASING ZONE
Due to the nature of sizing, the yarns in the sheet may be stuck together at the exit of
dryer section. Therefore they are separated into individual ends using leasing rods. The
individual sheets of yarns from each section beam are separated.
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3.11 EXPANSION COMB
Pins in the expansion comb separate the yarns within each sheet. With the expansion
comb the warps are spread according to the required width of the weaver‟s beam.
3.12 BEAMING
The yarns are wound on to weaver‟s beam at the headstock. Maximum beam width of
4000 mm can be used, usually 3600 mm is used. A pressing roller is pressing the warp
yarn for uniform tension winding. A guide roller guides the yarns to the weaver‟s beam.
A pressing roller is pressing the warp yarn for uniform tension winding. A machine speed
of 100-110 m/min. is used
3.13 TRANSPORTATION OF BEAMS:
After the winding of dyed warp beams the from the head stock the samples of the yarn
are taken to laboratory for testing and then it is transported to the weaving department.
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WEAVING
4.1 INTRODUCTION
The process of producing a fabric by interlacing warp and weft threads is known as
weaving. The machine used for weaving is known as weaving machine or loom. Weaving
is an art that has been practiced for thousands of years. The earliest application of
weaving dates back to the Egyptian civilization. Over the years, both the process as well
as the machine has undergone phenomenal changes. As of today, there is a wide range of
looms being used, right from the simplest handloom to the most sophisticated loom.
4.2 BASIC WEAVE DESIGNS
There are three basic weaves:
• Plain weave
• Twill weave
• Satin Weave
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4.3 Weaving of Denim Fabric:
Denim is a fabric traditionally woven with what is known as a twill weave. This is simply
a weaving pattern that produces parallel diagonal ribs. The weaving process interlaces the warp, which are the length-wise indigo dyed yarn and
the filling, which are the natural-colored cross-wise yarn. The warp thread is in the form
of sheet.
In denim, the warp-faced twill pattern calls for passing the weft yarn over one and under
two (1/2), or over one and under three warp (1/3) yarns. Because there are fewer lacings
in twills than in plain weaves, the yarns are freer to move when being worn resulting in a
fabric that is both flexible and resilient.
The weft thread is inserted between two layers of warp sheets by means of a suitable
carrier, such as Shuttle, Projectile, Rapier, Air current, Water current, etc. The selection
of carrier depends upon the type of weaving machinery used. The two different
technologies available for weaving machines are - Conventional Shuttle Weaving System
which is done by Ordinary Looms or Automatic Looms; and the Shuttle less Weaving
System which is done by Airjet, Waterjet, Rapier, or a Projectile weaving machine. The
Conventional Shuttle loom results in lesser production due to slow speed and excessive
wear and tear of machinery. As such, now denim is generally woven through Shuttle less
Weaving System namely, Airjet looms, rapier looms or projectile looms.
The most common twill used for jeans is a 3x1. A 2x1 twill is used in lighter weight
denim.
The yarns used in making denim have a very high twist, a process which gives the yarn
much greater resistance both to tensile stress and to abrasion.
4.4 Typical Denim Constructions, Weaves, and Weights
The classical construction of a bottom weight 14.5-ounce denim is 60-64 warp yarns per
inch and 38-42 filling yarns per inch. The number of warp yarns per inch is sometimes
referred to as the fabric sley. The weight is influenced by the size of the yarn used, the
fabric weave design, and the fabric tightness. Also influencing the fabric weight is the
amount of size left on the finished fabric. Other denim fabrics and denim “look -a-likes”
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may vary in construction from 52 to 70 warp yarns per inch and from 36 to 52 picks per
inch. As a rule, denim is woven as 3/1 twill, 2/1 twill, 3/1 broken twill, or 2/2 broken
twill. The weights of these finished fabrics can vary between 3.5 and 16.5 ounces per
square yard. The weight of the fabric usually determines what the final garment
application will be:
Numerical notations for different denim designs, such as 3/1, denote what each warp yarn
is doing relative to the filling yarns that it is interlacing with. In this case, each warp yarn
is going “over” three picks and then “under” one pick. This would be verbally stated as
“3 by 1” twill or “3 by 1” denim. At the next end, moving to the right, the same sequence
is repeated but advanced up one pick. This advancing upward sequence continues, giving
the characteristic twill line. In this case, the twill line is rising to the right, and the fabricis classified as a right- hand twill weave. If the twill line is made to rise to the left, then
the design is left-hand twill. Broken twills are designed by breaking up the twill line at
different intervals thus keeping it from being in a straight line.
Left Hand Twill:
This refers to the direction that the denim is woven. Left hand twill denim is softer to the
touch than right hand twill, and was originally used by Lee denim. Left hand twill is easy
to spot, as the weft threads appear to move upward and to the left as opposed to upward
and to the right.
Right Hand Twill:
This refers to the direction that the denim is woven. The opposite of Left Hand twill, this
weave is much more common, as almost all jeans are woven with right hand twill. The
weft (filler) threads will be visible in upward-right diagonal lines on right-hand twill
jeans.
Broken Twill:
Instead of the twill running to the right or left, broken twill jeans (traditionally considered
the cowboy-preferred denim) contain no distinct direction of weave. The weave is instead
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alternated right and left - the end effect resembles a random zig-zag. Broken Twill was
designed to combat the twisting effect that was a characteristic regular twill (and
considered a 'fault' by many at the time). By going on both directions, the tension in the
yarns is balanced in Broken Twill.
4.5 Non-conventional Denim Fabric Constructions
Indigo-dyed yarns have been woven in plain weaves known as chambray, oxfords,
baskets, herringbones, bedford cords, and combinations of 3/1 and 1/3 twills. Jacquard
designs and dobby weaves have also been incorporated into denim designs to produce
new looks and textures.
Twill Weave
Twill Weave is produced in a stepwise progression of the warp yarn interlacing pattern.
The interlacing pattern of each warp yarn starts on a different filling yarn and follows the
same formula. These results in the appearance of a diagonal line called twill line in the
fabric, which is then characteristic of this design. Depending on the direction of the twill
line, the twill weaves are called right-hand or left-hand twills. The sum of the digits in
the formula determines the unit cell of the design, which also gives the minimum number
of harnesses, requires weaving the design; at least three harnesses are required for a twill
weave. Common twill, Steep twill, Reclining twill and Broken twill are the different
variations of the twill weave.
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4.6 SHEDDING SYSTEM:
There are four shedding systems used to provide manipulation to the warp yarns:
1. Crank Shedding
2. Cam Shedding
3. Dobby Shedding
4. Jacquard Shedding
4.6.1 CRANK SHEDDING:
This is the simplest shedding system. In this system, the crankshaft of the weaving
machine provides the harness motion. This system is used only for plain weave and its
derivatives.
4.6.2 CAM SHEDDING:
A typical cam system can handle weave patterns with up to 14 different harnesses. Cam
shedding mechanisms are relatively simple. A pair of cams is sufficient to weave plain
fabric. A cam is a disk that transforms a rotational motion of its own to a reciprocating
motion of a follower. The transfer is done by means of the cam‟s edge or a groove cut in
its surface.
4.6.3 DOBBY SHEDDING:
Dobby mechanisms are more complicated than cam systems. They are normally built to
control up to 30 harnesses. Picks per repeat are virtually unlimited in dobby. Basically
there are two separate functions in dobby mechanism: 10 power transmission, 2)
connection and disconnection of the harnesses to from the power source at the proper
time. Dobby mechanisms are classified as negative, positive and rotary dobby. They can
be mechanical or electronic.
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4.6.4 JACQUARD SHEDDING:
Jacquard Shedding offers unlimited patterning possibilities. The Jacquard machines offer
the highest level of warp yarn control. This versatility is due to the separate control of
each warp end or groups of similarly interlacing warp ends within the pattern repeat
across the fabric width. They enable the most sophisticated patterns, such as pictures, to
be produced in the woven fabrics. Jacquard machines can be mechanical or electronic
with single lift or double lift mechanisms; the new machines are all double lift. Most
Jacquards heads generally are equipped to handle over 2000 harness cords or hooks with
pattern repeating on about on about 9000 picks and multiple heads can be employed over
a single weaving machine to increase the weave pattern capability. Jacquard systems are
placed on top of the weaving machine.
FILLING INSERTION:
After each shed change, the filling yarn is inserted through the shed. It is possible to
select and insert different filling yarns one after another.
Weaving machines are usually classified according to the filling insertion mechanism.
The major filling insertion systems used today are rapier, projectile, air-jet, and water-
jet, which are called shuttle-less weaving systems.
4.7 CLASSIFICATION OF WEAVING MACHINES:
Weaving machines are classified according to their filling insertion mechanism. The
classification is as follows:
1. Shuttle
2. Shuttle-less
• Rapier • Projectile
• Air-Jet
• Water-Jet
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4.7.1 Shuttle Weaving
In shuttle weaving, a shuttle that traverses back and forth across the loom width, inserts
the filling. Shuttles can be made of wood or plastic. Filling yarn is wound on the quill andthe quill is placed in the shuttle. As the shuttle move across the loom, the filling yarn is
unwound from the pirn and lay in the shed.
4.7.2 Shuttle-less Weaving:
Rapier Weaving
In Rapier weaving, a flexible or rigid solid element, called rapier, is used to insert the
filling yarn across the shed. The rapier head picks up the filling yarn and carries it
through the shed. After reaching the destination, the rapier head returns empty to pick up
the next filling yarn, which completes the cycle. A rapier performs a reciprocating
motion.
Rapier weaving machines can be of two types:
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1. Single Rapier Machines: A single, rigid rapier is used in these machines. The
rigid rapier is a metal or composite bar usually with a circular cross section. The
rapier enters the shed from one side, picks up the tip of the filling yarn on the
other side and passes it across the loom width while retracting. Therefore, a single
rapier carries the yarn in one way only and half of the rapier movement is wasted.
Also there is no yarn transfer since there is only one rapier. The single rapier‟s
length is equal to the width of the loom.
2. Double Rapier Machines: Two rapiers are used in these machines: one rapier,
called the giver, takes the filling yarn from the yarn accumulator on one side of
the loom, brings it to the center of the machine and transfers it to the second
rapier which is called the taker. The taker retards and brings the filling yarn to the
other side. Similar to the single rapier machines, only half of the rapier
movements is used for filling insertion
Projectile Weaving
Projectile weaving machines use a projectile equipped with a gripper to insert the filling
yarn across the machine. The gripper projectile draws the filling yarn into the shed. The
Projectile glides through the shed in a rake- shaped guide. Braked in the receiving unit,
the Projectile is then conveyed to its original position by a transport device installed
under the shed.
Air-Jet Weaving
Air-jet weaving is a type of weaving in which the filling yarn is inserted into the warp
shed with compressed air. Air-jet system utilizes a multiple nozzle systems and a profiled
reed. Yarn is drawn from a filing supply package by the filing feeder and each pick is
measured for the filling insertion by means of a stopper. Upon release of the filling yarn
by the stopper, the filling is fed into the reed tunnel via tandem and main nozzles, which
provide the initial acceleration. The relay nozzles provide the high air velocity across the
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weave shed. Profiled reed provides guidance for the air and separates the filling yarn
from the warp yarn.
Water-Jet Weaving
A water-jet weaving machine inserts the filling yarn by highly pressurized water. The
relative velocity between the filling yarn and the water jet provides the attractive force. If
there is no velocity difference, then there would be no tension on the yarn results in
curling and snarling of the yarn. Water-jet weaving machine can only be used for
hydrophobic fibers.
Beat-up
When the filling yarn is inserted through the shed, it lies relatively far from its final
position. This final position is called the fell, which is the imaginary line where the fabricstarts. Beat-up is the process of pushing the last inserted filling yarn to the cloth fell by
using a device called reed. The fabric is not formed until beat-up occurs. Reed is a closed
comb of flat metal strips. These metal strips are uniformly spaced. The spaces between
the metal strips are called dents. The reed is also used to control the warp yarn density
(ends/inch) in the fabric, which affects the weight of the fabric. The reed holds one or
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more warp yarns in each dent and pushes them to the cloth fell. After beating up the filing
yarn, the reed is withdrawn to its original rest position before the insertion of the next
filling. Reeds are identified by a “reed number‟ which is the number of dents per unit
width. Specifying the number of ends per dent with a certain reed number dictates the
density of warp yarns in the fabric. Reeds are of two types according to their shape;
Regular reed and Profiled reed (used in air-jet weaving). Reed can be single or double. A
double reed has two rows of metal strips. The rear row starts from the middle of the first
dent of the front row of the metal strips. The double reed is used in terry weaving.
Fabric take-up
As the fabric is woven, it should be removed from the weaving area. This is achieved by
the take-up motion. The fabric take-up removes the cloth at a rate that controls fillingdensity (picks per inch).
LOOMING
Looming covers the process involved in warp preparation after sizing up to setting them
to loom. The process can be shown as follows:
Drawing-in → Warp Tying → Loom
During slashing, the exact number of warp yarns required in fabric is wound on to theloom (or weaver's) beam. The warp ends are then passed through the drop wires of the
warp stop motion, the heddles of the harness frames and the dents at the reed. This can be
achieved by drawing -in or tying -in, the choice depending upon whether or not the new
warp is different form the warp already on the loom.
DRAWING-IN
The process of drawing every warp end through its drop wire, heddle eye and reed dentcan be performed manually or by means of automatic machines. In both case, a length of
warp yarn, just enough to reach to the other side of the frame, is unwound. Leasing (i.e.
selecting warp) of the warp at this stage simplifies the separation of the yarns. Then they
are threaded through drop wires heddle eyes and reed dents. The automatic drawing
machine can handle the leasing-in and drawing -in process in one single operation.
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TYING-IN
When fabric of a particular type is being mass-produced, the new warp beams will be
identical with the exhausted beams on the looms. Therefore, if every end on the new
beam is tied to its corresponding end on the old beam, the drawing-in process can be
omitted. Tying-in may be done by means of a small portable machine on the loom or as a
separate operation away from the loom.
FAULTS IN DENIM PRODUCTION
5.1 FAULTS OF WARPING:
5.1.1 FALUTS IN MACHINE:
• Stop motion does not work on creel and on warping drum as a result broken ends
are not traceable for knotting.
• Chain breakages
• If frictional drum should not be kept in a polished state, then thermal damages occur
due to abrasion.
• Brake could be inefficient.
• Sprockets are jammed.
• If comb do not move properly then there is a chance of cutting of comb due to
friction with yarn.
• Tension supplied if varied it causes breakages or loosening in yarn.
• If speed of warper increase than yarn sheet may break
5.1.2 FALUTS IN RAW MATERIAL:
• Neps
• Long thick places (in case of non slub yarn)
• Short thick places (in case of non slub yarn)
• Thin places
• Weak places
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• Count variation
• Hairiness
5.1.3 FALUTS IN PRODUCT:
• Misalignment of yarn sheet if the yarn sheet is not properly adjusted
• Uneven package density
• Too soft package winding
• Package could not be in uniform density
5.2 FALUTS OF DYEING:
5.2.1 FALUTS IN MACHINE:
• leakage of steam in drying cylinders
• wear and tear of rollers if bearing is jammed
• Improper working of load cell on squeezing roller. Which causes entanglement of
warp sheet as pressure is not properly distributed
• Faults in dosing system can cause serious problem of shade variation.
• If the accumulator do not work properly than the machine is stopped.
• If speed of the machine is kept greater than the yarn` s bearable strength
5.2.2 FALUTS IN RAW MATERIAL:
The main causes of the dye ability variations in yarn are:
• Immature fibres
• Dead fibres
• Vegetable matter or other foreign matter
• Wrong twist
• Bad splice
• Neps
• Count variations
5.3 SIZING FAULTS:
• pressure rolls do not work properly
• squeezing rollers do not work properly
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5.4 WEAVING FAULTS:
• dropper will not fall
• sensors do not work properly
• Problem in electrical panel
• Problem in electronic card
• wear and tear of temple
• if dust comes in nozzles
DENIM WASHING
6.1 INTRODUCTION:
Denim washing is the aesthetic finish given to the denim fabric to enhance the appeal
and to provide strength. Much of the appeal of dry denim lies in the fact that with time
the fabric will fade in a manner similar to that which artificially distressed denim
attempts to replicate. With dry denim, however, such fading is affected by the body of
the person who wears the jeans and the activities of their daily life. This creates what
many feel to be a more natural, unique look than pre-distressed denim.
6.2 HOW DOES WAHING CREATE UNIQUE LOOK?
Washing of the denim cause it to fade which result its unique look. There are at least
three fundamental reason that indigo dyed denim washes down to produce lighter and
more attractive shades during washing.
the outer more heavy dyed yarn surfaces loses dyed through abrasion by stones,
enzymes and chemical effect.
Indigo dye has intrinsic chemical instability to strong oxidizing agent such as chlorine
bleach.
Some of the undyed fiber in the interior of the yarn migrate to the yarn surface
diluting the color of the yarn.
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6.3 There are two process involved in DENIM WASHING.
1. DRY PROCESS 2. WET PROCESS
6.3.1 DRY PROCESS:
It is called Dry Process because all the processes which are listed below is
done in dry condition, in the other says we don‟t use any chemical including
water in this process.
Following process are carried out in DRY process. Which are listed below?
1. Brushing
2. Hand whisker
3. Grinding
Hand Grinding
Wheel Grinding
4. Tagging
5. Clipping
BRUSHING or HAND SANIDING or SCRAPING:
Hand sand is step which is generally being done in rigid form of garments to get distress
look. Locations can be front thigh & back seat or its can be overall / global application as
per Standard.
In this department dyed garment (denim) is scrabbled or brushed using Emery paper.
Scraping can be done on inflated rubber balloons for better effect ( horizontal or vertical
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its up to operators convenience ) , even it can done plain wooden board of garment size &
hand pressure should be uniform in order to get better results.
The garment is wear on the machine (horizontal or vertical machine) which have two legs
is filled by air (air is directly come from the compressor).then we start brushing with the
help of emery paper until our required effect is achieved. Different types of emery paper
are used e.g 100,120,320,400 and 600 grain size. The selection of the emery paper is
depend upon the fabric weight i.e. if fabric is light then we use emery paper of
320,400,600 grade, normally 320 grade of emery paper is used and for heavy fabric high
emery paper of 100 and 120 are used. By brushing the dye is removed from the surface of
the garment.
HAND WHISKER:
In this process the same machine is use as used in brushing. On Denim,
whiskers/Chevrons are nothing but the worn out lines / impression generated by natural
wearing on hip & thigh area. There are many designs & pattern available.
This is being done manually with help of sharp edge Emery paper rolled on fine wood
stick or pasted on plastic material. Before starting execution placements & pattern must
be marked on garments, this will help operator to execute the pattern right to match the
aesthetics of garment. Hot spots are heavy/intense area on thigh or knee which is made
purposely to create used look & on knee area if any whiskers line are there, called knee
star.
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GRINDING:
Edge distressing or grinding is the process of destruction on jeans form edges of the
garment. When we look at old jeans we find it destroyed from the edges of pockets, fly
area, belt and bottom. This used effect can be created on jeans by grinding and is of key
importance in high fashion garments.
It include the following processes.
PATTERN MAKING:
In grinding first the pattern is make of different designs then these pattern is mark on the
grinding areas in the garment with the help of chalk. by doing all these the grinding area
on the garment is become visible.
PADDING:
This is the main process of grinding in which fabric is put on the plate, which have a
rubber pad of same pattern or design which is already mark on the garment .then emery
paper is rubbed against the garment which remove the yarn from the garment to get the
desire effect. 100 grade of emery paper is use for this process.
HAND GRINDING:
This is the process in which garment is slightly damage by removing surface yarn with
the help of hand grinding machine. Hand grinding is done on the small areas while
padding is done on large areas. The effect of both process (padding and hand grinding)
are approximately same.
Grinding is done of garments by pen type of stone tools. It can be done in mid of the
wash process. In many workshops it is done before any wash process as first process after
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stitching. Stone tools similar to grinders used in wood and stone industry are utilized to
work on garments with a few amendments to their design.
Pen type tools are very affective for this art work but consistency is always a big question
while dealing in production. They are not much effective in large quantity production
units. Staff is to be very experienced and careful other wise it may damage the garment
beyond requirement. To work on edges is very sensitive and any heavy destruction will
open the edges and make the garment not to wearable. This aspect needs special care and
supervision in industry.
WHEEL GRINDING:
In this process the edges of the garment like edges of the waist band, bottom hem, front
pocket, back pocket and back pocket cover are grind using wheel grinding machine.
In high production units it is usually done with fixed grinding machines where grinding
stone wheals fixed on high speed electrical motors. Operators rub the edges to rotating
stone wheal to get the effect. Again the risk of damage to extent where the edges get
opend is there and to avoid it strict supervision and skilled staff is of key importance.
This method is very time and cost effective and large quantities are always deal in this
way.
TAGGING:
Tacking or more commonly tag pinning is a very in fashion style in denim garment in
these days. Usually tag pin machines are used to attach tag pins to garment. The
procedure is very simple and proceeds as; garment is folded on required area and tacked
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through folds. Garment is folded on specified areas and the fold is locked by tag pins.
Now the garment is processed in washer and a permanent fold appears after removal of
tag pin. This is important that tag pin is removed when the garment is dried completely.
The inner of the fold is dark in shade due to less exposure to mechanical rubbing and
chemicals.
Area of Application :
This effect can be designed any where on the garment in different styles. Most favorite
areas for tacking are on waistband, bottom hems, back pocket and front pocket corners
etc
Tag Pin Tagging Machine
CLIPPING:
In this process the small areas of the garment is bound by using clips on the required
areas (generally at the bottom hem) then garment is put in the oven and finally forward to
the washing dept. for final effect.
6.3.2 WET PROCESS
It is called wet process because in this we use certain chemicals to obtain a desired
result.
1. Pre-Treatment
2. Washing
3. Enzyme wash
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4. Bleach wash
5. Stone wash
6. Sand Blasting
7. Tinting
8. Over dyeing
9. Spraying
10. Whiskering
PRE TREATEMENT
This is very first & basic step but most important step of washing. Here the fate of denim
garment is decided that it‟s going to appear good or bad. Good Pre treatments avoid
streaking, stiffness & color loss. This process removes impurities, starch & stains duringhandling of fabric. This step is also called desizing (Removal of Size applied during
denim fabric making in weft yarn). All the woven fabric contains size on them due to
reasons to strengthen the yarn for weaving. There are many types of sizes available in the
market but they can be divided in two major groups.
1. Water Soluble (CMC or PVA based sizes ) and
2. Dissolvable sizes in water (Starch based). Starch based sizes are most commonly
used due to cheap prices & readily availability.
Methods of Removing Sizes from Denim:
· Washing with High Alkaline agents ( i.e. Soda ash )
· Washing with High Acidic agents (i.e. Acetic acid )
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· Washing with Oxidative chemicals ( i.e. Hydrogen Peroxide )
· Enzymatic desizing with Alfa amylase .. This is eco friendly & convenient .
6.4 DENIM WASHES ARE OF TWO TYPES:
6.4.1. CHEMICAL WASHES:
- Denim bleaching
- Enzyme wash
- Acid wash
- Tinting
- Over dyeing
DENIM BLEACH:
This in one an important step in washing denim & can be done by various bleaching
agents.
a) Calcium hypo chlorite
b) Sodium hypo chlorite
c) Hydrogen peroxide
d) Potassium permanganate
First two chemicals are commonly being used for every medium to vintage denim but
when it comes to super vintage & light shade its advisable to use potassium
permanganate bleach to cut the color faster till half way & then neutralize it & go with
Liquid ( Hypo ) bleach to adjust the desired shade. This process helps to get Greyer cast
& also protects the lycra/spandex, retain elasticity.
Hydrogen Peroxide is rarely used as bleaching agent when very less color loss required or
if fabric is sulphur top. As it takes longer time to give desired effect.
Potassium Permanganate is also being used on 100% sulphur black denim fabric for
bleaching/reducing agent to get unique effects. As it‟s not production friendly till laundry
has very expertise team to handle this program, otherwise it will result in many shades &
cast. Proper Neutralizations of bleaching process is very essential in order to get rid of
fabric strength, bad smell from garment, yellowing & skin irritation etc.
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In this process a strong oxidative bleaching agent such as sodium hypochlorite or
KMnO4 is added during the washing with or without stone addition. Discoloration
produced is usually more apparent depending on strength of the bleach liquor quantity,
temperature and treatment time. It is preferable to have strong bleach with short treatment
time. Care should be taken for the bleached goods so that they should be adequately
antichlored or after washed with peroxide to minimize yellowing. Materials should be
carefully sorted before processing for color uniformity.
Process cycle
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LIMITATION:
Process is difficult to control i.e. difficult to reach the same level of bleaching in
repeated runs.
When desired level of bleaching reached the time span available to stop the bleaching is very narrow. Due to harshness of chemical, it may cause damage to
cellulose resulting in severe strength losses and/or breaks or pinholes at the
seam, pocket, etc.
Harmful to human health and causes corrosion to stainless steel.
Required antichlor treatment.
Problem of yellowing is very frequent due to residual chlorine.
Chlorinated organic substances occur as abundant products in bleaching, and
pass into the effluent where they cause severe environmental pollution.
RANDOM BLEACH:
It is an uneven effect, some time also known as cloudy effect. In which denim is
bleached indirectly via towel piece or cotton balls it produce more merge and cloudy
effect cotton ball is more successful but cotton towel are some tome used to produce
more cloudy effect.KMnO4 cannot be used with cotton balls/ribbons. It is only possible
with hypochlorite. Black sulfur is not process able with hypochlorite as sulfur reacts
vigorously with sulfur and pace of process cannot be controlled.
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Procedure:
In this process we take bleaching agent in washing machine then we put small pieces of
towel or cotton (raw cotton) then we will run the machine for few minutes until the towel
soaked the bleaching agent. Then we drain the bleach after that we put the garments in
the machine with towel pieces and run the machine until we get a required effect. We
immediately neutralize the garment to prevent bleach spots or patches.
ENZYME WASH:
It is environmentally friendly wash. It involves the Application of organic enzymes that
eat away at the fabric, i.e. the cellulose.
When the desired color is achieved, the enzymes can be stopped by changing the
alkalinity of the bath or its temperature. Post treatment includes final rinsing and
softening cycle. The effects produced by the cellulose enzyme are---
1. Use of cellulase making the seams, hems, and pockets more noticeable
2. Salt pepper effect is color contrast effect.
3. Faded garment with acid cellulase enzyme provides less color contrast in
proportion to garment washed with neutral cellulase enzymes.
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There are four kind of Enzymes available in market for Denim Laundry business..
Amylase …. Desizing
Cellulase …. For Salt & pepper effect , contrast
Laccase…. … bio bleaching
Catalase …… Peroxide killer
Enzyme is kind of protein that is obtained from fermentations method from naturally
existing bacteria & fungi. The structure of Enzyme is a biological polymer and it can be
found in every cell. Generally called as Cellulase & it works on cotton( Cellulosic fiber )
only. Enzyme are living organisms which will attack a specific molecular group.
There are mainly three kind of Cellulase being used for Denim washing , Neutral, Acid
and Bio polishing Enzyme. Enzyme are very sensitive with parameters in washing cycle
i.e, pH , Temperature & time. If any of these parameters are not up to the mark, result
will not be accurate. The reaction of enzyme can be easily controlled, its biodegradable
products, so they eco friendly. Bio Polishing Cellulase are being used to have protruded
fiber removal from denim & oven fabric. This is also widely known as Anti pilling
enzyme. Any Cellulase used in process must be cleaned/killed after the process
completion by simply disturbing the parameters ie. By raising high temp. or raising pH to
alkaline where no Cellulase withstand.
Cellulase are available in 3 categories
1. Neutral
2. Acidic
3. Hybrid enzymes.
Neutral enzyme gives better salt & pepper effect with very less back staining & its
generally come sin powder form & also retains better strength of fabric than acidic
Cellulase. Where as acidic cellulase give faster results but with too heavy back staining &
cuts down the indigo color, also affects the strength of fabrics. Now a days laundry
people needs faster results in less time & money hence chemical suppliers combined
Neutral & acid cellulase in such way that it works faster & with better results than acid
cellulase with cost effectiveness & known as Hybrid enzyme. Laccase is bio bleaching
agent & alternative for conventional bleaching agents. This impart greyer cast to blue
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denim & enhances salt & pepper effect. But due to high cost & low self life, laundries do
not prefer it.
CLEAN UP:
After finishing Enzyme wash it is must to add clean up process for better results &
garments appearance & that can be done in various ways & methods. As clean up is a
must process to be carried out after every chemicals steps done for any garments which
allows next process to happen smoothly. All processes mentioned below kill/ deactivate
the active enzymes process which is necessary in order to protect/retain garment strengt
Hydrogen peroxide in alkaline pH clean up enhances the brightness & rich blue
tone of indigo.
By using non ionic detergents in medium to high temperature
By doing two good hot water rinse etc.
Process cycle:
ACID WASH:
This is the oldest of fashion washes in denim after stone wash. The name acid wash is in
reference to the acids used for this wash in old recipes. In new methods it is done with
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oxidation. Use of bleach/oxidative is very safe and economical in comparison to acids.
Different chemicals are used and among them potassium permanganate (KMnO4) and
sodium hypochlorite are mainly used. Acid wash is typically done by soaking pumice
stone in hypochlorite. Some time KMnO4 is used in replace of bleach. Selection of
oxidant is very important and mainly depends on the type of fabric. When it is done with
pumice stone the washer and garment should not contain any water. Dry garment is much
suitable for this process then a damp one. Pumice stones are soaked in bleach and left it
to open for little time so they get only damp rather than wet. Then they are processed in
machine with garments. The extent of effect is controlled with process time,
concentration of oxidant solution and quantitative ratio of garment to stone.
Process cycle
LIMITATIONS OF ACID WASH
Acid washed, indigo dyed denim has a tendency to yellow after wet processing.
The major cause is residual manganese due to incomplete neutralization,
washing or rinsing.
OVER DYE:
Dyeing over the fabric or jeans to add another tone of color
Most often used is a 'yellowy' over dye to create a 'dirty' look
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Also can be applied with spray gun or paintbrush for local coloring
There are many variations. Blue and black can be overdyed with bright contrasting
colours to obtain special effects. The most current and successful forms of overdyeing
consist of dyeing washed out indigo jeans with luminous colours. In this process direct
dye is applied into already Indigo dyed garment. It takes 10 pieces of garment and put
into the washing machine and add direct dye with all its auxiliaries and run it for 15
mins and check the shade then rinse.
TINTING:
Tinting is a process where very less amount of tint is involved & mainly direct dye is
being used to do this process. This is being done to change hue/cast/tone of indigo. As
soon as quantity of tint color increases & it cover up indigo, reaches the level of dyeing.
Tinting being used to give garments a used / vintage & muddy look. This process takes
from 5 minutes to 15 minutes time for better results followed by dye fixing & cleans up
of superficial dye.
• The garment has been lightly colored in order to give the final denim appearance
• The techniques involve the addition of the colorant in the stone washing cycle.
• Because of this it must be insured that dyes and cellulose are compatible.
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PIGMENTS AND LOCAL TINT ( Staining) :
Need to choose right color of pigment or tint with binder or fixer to apply locally on
denim to get vintage look . This process also needs an artist to execute it nicely to merge
the tint with ground indigo color & should not look too artificial. Pigments & Local tint
also can be applied through spray gun or rubbing on desired area of denim garment. After
application its must be cured in order to have permanent effect on jean.
6.4.2 MECHAINCAL WASHES:
1. Stone wash
2. Bio stone washing
3. Sand Blasting
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STONE WASH:
Stone washing is a textiles manufacturing process typically utilized by the fashion
industry, in order to give a newly-assembled cloth garments a worn-out appearance.
Stone-washing also helps to increase the softness and flexibility of otherwise stiff and
rigid fabrics such as canvas and denim. In the process of stone washing, freshly dyed
jeans are loaded into large washing machines and tumbled with pumice stones to
achieve a soft hand and desirable look. Variations in composition, hardness, size shape
and porosity make these stones multifunctional. The process is quite expensive and
requires high capital investment. Pumice stones give the additional effect of a faded or
worn look as it abrades the surface of the jeans like sandpaper, removing some dye
particles from the surfaces of the yarn.
Process cycle:
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SELECTION OF STONE:
First pea gravel, then pumice, because they float around with the jeans,
instead of lying in the bottom of the water; Turkish stones are preferred
for their porosity and cleanliness or stones from Sicily,
but their supply is limited. Stone should be selected of the proper hardness, shape, and
size for the particular end product. It should be noted that large, hard stones last longer
and may be suited for heavy weight fabrics only. Smaller, softer stones would be used
for light weight fabrics and more delicate items.
Stone wt. /fabric wt. = 0.5 to 3 /1
It depends on the degree of abrasion needed to achieve the desired result. Stones can be
reused until they completely disintegrate or washed down the drain.
PROBLEMS CAUSED BY STONES
For instance stones could cause wear and tear of the fabric.
Damage to wash machineries and garment due to stone to machine and machine
to stone abrasion
Increase in labor to remove dust from finished garments.
Water pollution during disposal of used liquor.
Back staining and re deposition.
Denim is required to be washed several times in order to completely get rid of
the stones.
The process of stonewashing also harms the big expensive laundry machines.
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BACK STAINING AND RE-DEPOSITION
The dye removed from denim material after the treatment with cellulose or by a
conventional washing process may cause "back staining or "redeposit ion. Re-coloration
of blue threads and blue coloration of white threads, resulting in less contrast between
blue and white threads.
Remedy of back staining
Adding dispersion/suspension agent to wash cycle.
Intermediate replacement of wash liquor.
Using alkaline detergent like sodium per borate with optical brightener as after
wash.
Limitations of stone washing
Quality of the abrasion process is difficult to control Outcome of a load of jeans
is never uniform, little percentage always getting ruined by too much abrasion.
The process is non-selective.
Metal buttons and rivets on the jeans in the washing machines get abraded.
This reduces quality of the products and life of equipment, and increases
production costs.
Stones may turn into powder during the process of making the garment grayish
in color and rough too
Provides rougher feel than enzyme wash
Stone may lead the harm to the machine parts.
TIE AND WASH METHOD:
Tie & Wash also known as crunch wash or creaking pattern effect is very typical in high
fashion articles. The process is very simple but results to marvelous looks. Garment is
usually tied with white cotton strips and washed with stones. The exposed portions got
faded effects and a pattern of dark to light patches appears on garment. Different patterns
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can be formed by tying garment in different ways. More beauty is added when the edges
made by tying get prominent in form of white lines made by mechanical rubbing offered
by washer.
Procedure:
First we do the dry process of garment accronding to buyer requirement then we fold or
bind the garment and put it into the socks or net and tie it.then we put it into the wasing
machine with enzyme, stone, back stainer because in this process we get back staining
problem b/c it take a very long time. And we run the machine until we get our required
effect.
Then we drain it.we open the socks or net and again run the garment with stone enzyme
and back stainer to get a even effect(grains) in the garment.
Additional Applications:
Tumbler Run To improve the crunch effect some time it is better to run the tied / packed
garments in tumbler dryers for 20 min to 40 min before running in washer. Garment
should be wet but not dripping when running in tumbler.
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White Cotton Ribbon
Garment should always be tied with white cotton ribbons. If colored ribbons or
denim strips are used for tying then their color may deposit on garment to produce stain.
Cable Tie Method
In some of the industries, plastic cable tie is used to replace the cotton ribbons. It
is much expensive to cotton ribbons but much effective. Due to special construction of
cable tie plastic strips it is easy to keep the garment maximum tight. There is no risk of
getting it loose during process even it goes hours long. It is specially recommended to
Dark Washes where this effect is most difficult to get.
NET WASH:
Another method used for this effect is when net pockets/bags are used instead of tying.
The whole garment is packed tightly in net bag. It should not be fold in proper but a
random like filling of one garment to one bag will give appropriate effects. Then it is
stone washed in washer for a time ranges form 20 min to 80 min depending on the fabric
and pattern required.
Procedure:First we do the dry process of garment according to buyer requirement then we fold or
bind the garment and put it into the socks or net and tie it. then we put it into the washing
machine with enzyme, stone, back stainer because in this process we get back staining
problem b/c it take a very long time. And we run the machine until we get our required
effect.
Then we drain it. We open the socks or net and again run the garment with stone enzyme
and back stainer to get an even effect (grains) in the garment.
General Recipe Steps
Desizing (Tied Garment)
Stoning or/and Enzyming (Tied Garment)
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Soap Rinsing (Lose Garment)
Bleaching (if required)
Neutralization (if required)
Softener Application
BIO-STONE WASHING:
Many garments are subjected to a wash treatment to give them a slightly worn look;
example is the stonewashing of denim jeans. In the traditional stonewashing process, the
blue denim was faded by the abrasive action of pumice stones on the garment surface.
Nowadays, denim finishers are using a special cellulase. Cellulase works by loosening
the indigo dye on the denim in a process know as 'Bio-Stonewashing'. A small dose of
enzyme can replace several kilograms of pumice stones. The use of less pumice stones
results in less damage to garment, machine and less pumice dust in the laundry
environment. BioStonewashing has opened up new possibilities in denim finishing by
increasing the variety of finishes available. For example, it is now possible to fade denim
to a greater degree without running the risk of damaging the garment. Productivity can
also be increased because laundry machines contain fewer stones or no stones and more
garments. Below are some cellulases for denim finishing, each with its own special
properties. These can be used either alone or in combination with pumice stones in order
to obtain a specific look.
DISADVANTAGES OF CELLULASE TREATMENT
There are certain disadvantages of cellulase treatment. It could leave marks of
backstaining like blue threads becoming more blue or white threads becoming blue. To
get rid of such unwanted re-coloration of threads, the jeans are rigorously washed adding
surfactants to it. This process could result to color-fading of jeans and there is added
usage of water for the washing. Thus wastage of water and certain amount of
backstaining could be experienced. The primary target of stonewashing the denim with
pumice stones or enzymes is to provide the garment worn out, old and aged look.
Sometimes both stones and enzymes are used for the purpose.
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SAND BLASTING:
Sand blasting technique is based on blasting an abrasive material in granular, powdered
or other form through a nozzle at very high speed and pressure onto specific areas of the
garment surface to be treated to give the desired distressed/ abraded/used look.
It is purely mechanical process, not using any chemicals
It is a water free process therefore no drying required.
Variety of distressed or abraded looks possible.
Any number of designs could be created by special techniques.
6.6 SPRAYING:
PP Spray is being done on denim garments to achieve local abraded area to appear
whiter than back ground indigo color shade. This can be applied by spray gun or by towel
dipped in to PP Solution & rubbed on desired area followed by neutralization in wet
process. This process can be done in rigid after doing hand scrape or in the middle of the
wash. Doing after enzyme or bleach cycle will give more natural & white effect that
doing in rigid. There are many additives can be added in order to achieve desired
intensity and look.in order to use less amount of potassium permanganate we add a
activater (and it is also enviromently friendly process) and we get faster result with good
result.
The same way bleach solution also can be spray or rubbed on the garments on desired
area. But this process is very complicated & needs highly skilled operators to execute it
followed by immediate neutralization.
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ADVANTAGES
It is water free process therefore zero effluent discharge.
1. Less time consuming
2. Different designs are possible
3. Easy to use
4. No adverse effect on fabric strength.
6.7 WHISKERING (MALAVASI):
There are two types of machine in this dept.
1. Malavasi
Maximum temperature: 250 C
Maximum pressure: 1200 kpa
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2. Topper machine
Maximum temperature: 200 C
Maximum pressure: 250 psi.
In this process two types of whisker is produce.
1. Permenant Whisker
2. Non-permenant Whisker.
PERMENANT WHISKER:
These whiskers are those which are permanent and not remove either after the several
washes. In permanent whisker first resin is apply on the required area on the garment then
the garment is placed on the Malavasi machine. Temperature and pressure is set
according to the fabric e.g. for PC fabric temperature is 180-200 and pressure is 1200 kpa
while the time is 20-25 sec. These all parameters can vary according to the requirement.
After doing all these garment is put in the oven (to bake the resin coated area).
Crease lines around the crotch.
- Industrially done with laser, sandblasting, machine sanding, hand sanding and
abrasive rods.
- Also used for 'knee whiskers' (whiskers on the sides of knees) and 'honeycombs'
(crease marks on the back of the knee)
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Resin Application:Resin ( Formaldehyde free ) being used for achieving 3D effect ( 3 Dimensional ), Rigid
Look etc. This process can be done by spraying or dipping the garments in to Resin,
Catalyst, Silicone & PU solution in right combination according to the fabric strength &
desired effect needed. After application of resin solution in right proportion, make
manual designing as needed on the thigh, hip & back knee area. After making it , it
should be manually dried with hot press or hair dryer & then must be cured in oven at
right temperature, time as mentioned in resin product manual.If resin not cured properly,
3 D effect will not be permanent & can cause skin irritation/rashes to the wearer. Whole
garment can have crushed look by resin dip & crushed manually followed by oven
curing. Silicone plays an important role in getting softer hand after oven. Special streakyeffect & Crackles also being done by applying resin on desired area followed by scraping
& pp spray then neutralization.
RESIN RECIPE:
The purpose of resin is cross linking and the typical resin recipe are as follows:
Mg (as a catalyst)
ARCO Fix
Water
L:R 1:30
NON-PERMENANT WHISKER:
These are the whisker which are non permanent and can be removed easily.
In this process we spray water on the garment and put in malavasi machine.
6.8 SOFTENING PROCESS:
Softening process of Denim is very critical. As denim is very heavy in compare with
other fabrics hence its needs softening. During this process there is a big problem -the
discoloration of denim i.e change in shade or loss of whiteness, giving a yellow tint is
commonly known as yellowing. By using normal softener will lead to ozone problem.
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Indigo dyed fabric are even more prone to yellowing. As it‟s a widespread problem &
there in no single reason for its cause. Instead a number of condition can singly or in
combination lead to the problem. Yellowing in not specific to certain fibers, finishes or
washing processes. It is not specific to chemicals or chemical treatment but certainly
some of the factors among these can lead to the yellowing. As cotton & all organic
polymers develop yellowing in time. Light , acids, impurities, detergents & chemical
contribute to yellowing problems. Temperature of drying & curing can impart yellowing
due to scorching of the cotton. Therefore good control must be used to minimize this type
of damage. Hence its advisable to use Antiozonate softener which prolong ozone reaction
of Indigo & keep garment in good condition.
MINIMISATION OF YELLOWING RISK
Its Impossible to eliminate yellowing but it is possible to prolong & reduce the conditions
which causes classical yellowing.
Ensure bleaching neutralization & rinsing is proper
Minimize back staining
Avoid use of chemicals which cause yellowing
Avoid leaving garment in open air for longer time
Control drying & curing temperatures
Using right Antiozonate softener with right pH
CHEMICALS ON DENIMS
1. Bleach fast Indigo
Value addition to denim
Retains indigo on certain parts
Kind of resist effect
Chemical applied by brush, cured at 150C
Ex. Indigofix AXN
2. Anti-depositing agent
Prevents back staining of fabric by loose indigo during washing
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Improves contrast in denim
Used in stone wash step
3. Dye stuffs with softener
To carry dyeing and softening in one step
Soft and supple hand
Saves time, money and energy as added to final rinse
Gives used and worn out effect
4. Anti creasing agent
Provides fabric to fabric lubrication
Prevents formation of crack marks and streaks
Minimizes abrasion and gives strength
5. Wrinkle formation
Creating smooth and permanent wrinkle
Cross linking concept Ex. DMDHEU
White pigment
Can be applied by brush, spray or screen
Then cured at 150C
Washed and treated with softener
6. White pigment
Can be applied by brush, spray or screen
Then cured at 150C
Washed and treated with softener
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PROCESS RCIPE SHEET:
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6.9 MACHINE USE FOR DENIM WASHING:
TONELLO MACHINE:
Machines suitable for all types of washing processes, such us stone washing, bleaching
and other washing treatments on garments of different materials (cotton, linen, viscose,
tensel treatment etc). Particularly indicated for the treatment of jeans, they are supplied
with baskets provided with special beaters, speeding up the process and guaranteeing at
the same time uniformity in the treatment and softness to the denim fabric. They have
variable speed and are equipped with an industrial B&R PC and a PLC Mod. PP 200. The
software, and in particular the “Wash program”, entirely worked out by Tonello‟s
engineers, allows to manage and to control all the functions of the machine as well as the
process operations. It is possible to store up to 500 recipes (with 200 steps/each).
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G1 420 LS EV1
Made in Italy
Patented
Technical Data G1 420 LS EV1
Cylinder Volume 4180 l
Cylinder Dimensions Ø1890x1490 mm
Variable Speed 0/110 rpm
Installed Power 17 kW
Dimensions
Height 2600 mm
Width 2940 mm
Depth 3100 mm
Weight 4400 kg
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6.10 NEW DEVELOPMENTS TOWARDS ECONOMICAL AND
ECOLOGICAL DENIM PROCESSING
USE OF LASER TECHNOLOGY:It is a computer controlled process for denim fading. This technique enables patterns to
be created such as lines and/or dots, images, text or even pictures. In one version of this
concept, a mask is used to give the desired shape that is to be applied on the fabric. The
laser projects through a lens system, which expands the beam. This beam is passed
through the shaped mask that comprises an aperture of the desired shape and is then
deflected by a mirror to strike the textile substrate. The duration of exposure determines
the final effect on the fabric.
The novelty of this system is that
It is water free fading of denim.
It is an ecological and economical process.
It can create local abrasion and fabric breaks, used look effect, moustache with
excellent reproducibility and higher productivity.
Being an automatic system, chances of human error are slim.
The design is electronically translated on the fabric, thus avoiding the need for
photolites of serigraphy cleaning.
The machine is very simple and compact, therefore requires very low
maintenance and cleaning, extremely safe and reliable.
The machine is very simple and compact, therefore requires very low maintenance and
cleaning, extremely safe and reliable
OZONE FADING:
By using this technique, the garment can be bleached. Bleaching of denim garment isdone in washing machine with ozone dissolved in water. Denim garments can also be
bleached or faded by using ozone gas in closed chamber. The advantages associated with
this process are:
Color removal is possible without losing strength.
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This method is very simple and environmentally friendly because after
laundering, ozonized water can easily be deozonized by UV radiation.
WATERJET FADING:
Hydro jet treatment has been developed for patterning and/or enhancing the surface
finish, texture, durability, and other characteristics of denim garment. Hydro jet treatment
generally involves exposing one or both surfaces of the garment through hydro jet
nozzles. The degree of colour washout, clarity of patterns, and softness of the resulting
fabric are related to the type of dye in the fabric and the amount and manner of fluid
impact energy applied to the fabric. Particularly good results are obtained with blue
indigo dyed denim.
As this process is not involved with any chemical, it is pollution free. By using water
recycling system, the technique can be used as economical and environmental friendly
denim processing. Color washout of dye in the striped areas produces a faded effect
without blurring, loss of fabric strength or durability, or excessive warp shrinkage.
SINGLE BATH STONE WASHING AND TINTING TECHNIQUE
Tinting of denim garment is usually done after the stone wash process. In this, garment
has been lightly coloured in order to give the final denim appearance a slight shift. This isnot true over dyeing but merely gives the impression of a change in overall colour of the
fabric. This process consumes large quantity of water and chemical. To make this process
economical and ecologically friendly, some novel colour based enzymes have been
introduced in the market. By using this new technique, tinting and stone washing effect
can be achieved in a single bath.
Less process time to achieve tinted look.
No extra chemical required therefore making process more economical.
Less water consumption.
Less energy consumption.
Less chance of patches or unevenness
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Alternate of pumice stone
To overcome the shortcoming of pumice stones, synthetic stones have been developed.
These are made of abrasive material such as silicate, plastic, rubber or Portland cement.
The advantages of using such type of products are:
All major problems associated with the use of volcanic grade pumice stone can be
overcome.
Durability of such product is much higher and can be used repeatedly from 50-
300 cycle depending upon type of synthetic stone.
Reproducibility of washing is manageable.
As stone discharge of the process is very less, therefore making process is
economical and ecological.
Less damage of machine and garments.
6.11 VALUE ADDITION:
Globally, Denim designers are experimenting with fabric and garment details including
embellishments in order to add value to its garments. New add-ons are being incorporated
in the form of patches, appliqué, rhinestones and glitter. The process of adding value to
this legendary outfitter enhanced from time and time by devising some new methods such
as:
GETTING REVERSE EFFECT ON DENIM IN DISCHARGE PROCESS:
In spray process, first apply neutralizer where you want the resist effect and thereafter,
spray potassium permanganate on applied portion and its surrounding area. Then,
neutralize the garment to remove potassium permanganate. It gives a halo effect to denim
garments.
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TINTING WITH WHITE DISCHARGE EFFECT ON DENIM GARMENTS:
The standard route to blasting/discharging/tinting is quite elaborate, in the light of three
effects to be imparted on the same garment. There have been short cuts, which may be
right/wrong/ingenious. If tinting is done on blasted/discharged areas, it obviously remains
a spray method. However, if the tinting is overall, it follows the dyeing route. The
process starts on gray garment being hand blasted followed by desizing and biopolishing.
After drying the garment, tint-spray is given followed by air/machine drying and
finishing. For tinting by dyeing method, the biopolished garment can straight away go for
tinting wet-on-wet followed by finishing and drying. In case of white discharge tinting
the route would start with desizing-biopolishing on gray garment, peroxide bleaching
after biopolishing being optional. After drying the garment, a potassium permanganate
spray is given to areas where white discharge is aimed at. After air-drying for about 10-
15 minutes, a neutralization step consisting of provide-acetic acid is given which is
followed by hot and cold rinses. In case of spray tinting the garment will have to be dried
first, whereas for overall tinting, dyeing the method could be followed wet-on-wet.
Finally the finishing and drying would complete the process.
SIGNIFICANCE OF OZONE-FASTNESS IN INDIGO GARMENTS:
Oxidizing agents have a property of attacking chromophoric group of the dyestuff and
destroying-discharging the color. Potassium permanganate is a well-known chemical
extensively used for discharge of indigo in denim garments. However, potassium
permanganate is used as and when discharge is required and the ultimate purpose is
value-addition. Ozone is another strong oxidizing agent, which could discharge indigo in
denim-garments. The folds in folded-denim garment otherwise have relatively greater
exposure to atmospheric ozone than the rest of the garment, which is protected by virtue
of garments being stacked. This results into localized discharge of indigo at the folded
marks. There are inorganic as well as organic ozone-seavenger, which protect the indigo
in denim garments from the attack of ozone and hence control the value-loss.
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TINT DENIM-GARMENTS WITHOUT CHANGING THE TONE OF INDIGO:
Tinting is achieved by application of the direct/reactive dyes. In case of direct dyes, the
second application would be that of dye-fixing agent for an adequate fastness. In case of
reactives, the fixing chemical goes along with the dyestuff. After the application, the
treated garment is dried in the air or in a tumble drier for adequate fastness. If tinting
were done by immersion method, the tint would be all over. However, if a localized area
is the target, a spray method is used. In either case the tinting, as the term signifies, is
done very lightly to achieve a particular cast, either overall or localized. If indigo does
not change tone would look like a print with a sharp boundary. When tone changes fad
gradient, the effect looks more aesthetically appealing and is considered desirable. The
tone-change should be gradual and not abruptive.
APPROACHES TO MILD WASHING EFFECTS ON SULPHUR-DYED DENIM
GARMENTS:
Garment washing may affect the whiteness level of your garments, as they can look dull
or yellow after processing. Most garment washers add whitener to the process to ensure a
bright white finished product. Make sure to determine any costs involved and factor them
into your product costing. There are many special effects, such as weathering, stone
washing, acid washing and distressing that can be produced by garment washers. These
effects being very popular have their own drawbacks. They are costly, have higher fallout
rates, and are generally rougher on the fabrics. Talk to your garment washer about prices
and what to expect of the process you choose to do.
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CONCLUSION
Our aim for making this report is to provide a new finishes and working on the
parameters and processes use in denim washing. In the whole report we have highlighted
denim washing processes and make our main focus on the processes and washes we had
done in rugby industries while in this report we also describe the manufacturing of denim
fabric. The demand of denim is increasing day by day. World-consumption of denim-
wears today is equivalent of about 4,500 million meters per year of denim fabrics.
So to meet this huge requirement of denim new finishes techniques is developed which is
economical and ecological and our textile industry follows all those processes.
Companies that “finish” jeans by washing them or distressing them for a worn-in look.
Most major jeans manufacturers use several different laundries that specialize in different
finishes. The main techniques used include simple washing, stonewashing, which uses an
abrasive-bristled Tonello machine, sandblasting, laser burning, or applying enzymes to
simulate “cat‟s whisker”-wear line, and sandpapering by hand.
Generally saying people who don‟t know about denim washing then after reading this
report you get a sound knowledge about the whole process which are carried out in denim
preparation and its washing. We include approximately all the major finishes and the
process which involve different operations e.g. wet process and dry process these two are
the main operation although there are also other process but they are the sub process.
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REFERENCES:
1. http://en.wikipedia.org/wiki/Denim
2. http://www.fashion-incubator.com/tutorials/warping
3. Dyeing and Chemical Technology of Textile Fiber by Trotman E.R
4. http://textilepedia.blogspot.com/2009/03/dyeing-process-for-denim.
5. www.thecompanymarketing.com/.../process-for-adding-value-to-denim
6. www.denimhelp.com/denim-garment-processing
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