32212852 Denim Washing Thesis

FINAL YEAR PROJECT REPORT

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 SALAMFACULTY MEMBER.

Email: [email protected]

SUBMITTED BY:SYED ASIM NAJAM

ID: 1002

MARCH, 2009

Indus Institute Of Higher Education1


ACKNOWLEDGMENTSAll thanks are due to Almighty “ALLAH” the most beneficial and merciful who enable

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.



Faculty of Textile ScienceINDUS 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 Najam2.

HOD Textile Science: ---------------------------

External Examiner: ----------------------------

Supervisor: ------------------------------



TABLE OF CONTENT

Content Page No.

Chapter 1

1.1 Introduction

1.2 Back ground

1.3 History of denim

1.3Literature Review

1.4 Area of study

1.5 Expected Results

Chapter 2 Warping

2.1 Introduction

2.1.1 Direct warping

2.1.2 Indirecy warping or sectional warping

2.1.3 Ball warping

2.1.4 Draw warping

2.2 Components of amchine

2.3 Procedure of warping

Chapter # 3 Dyeing

3.1 Introduction

3.2 Classification of dyes

3.2.1 Direct dyes

3.2.2 Reactive Dyes

3.2.3 Disperse Dyes

3.2.4Sulphur Dyes

3.2.5 Vat dyes

3.3 Denim dyeing

3.3.1 Rope dyeing



3.3.2 Slasher dyeing

3.4 Difference between rope dyeing and slasher dyeing

3.5 Cooking tanks and dsoing system

3.6 After-washing process and drying

3.7 Sizing

3.8 Drying zone

3.9 Accumulator

3.10Leasing zone

3.11 Expansion comb

3.12 Beaming

3.13 Transportation of beams

Chapter 4 Weaving

4.1 Introduction

4.2 Basic weave design

4.3 Shedding system

4.3.1 Crank shedding

4.3.2 Cam shedding

4.3.3 Dobby shedding

4.3.4 Jacquard shedding

4.4 Classification of weaving machine

4.4.1 Shuttle weaving

4.4.2 Shuttle less weaving

Chapter 5 Faults in production of denim

5.1 Faults of warping

5.1.1 Faults in machine

5.1.2 Faults in raw material

5.1.3 Faults in product

5.2 Faults of dyeing



5.2.1 Faults in machine

5.2.2 Faults in raw material

5.3 Sizing Faults

5.4 Weaving Faults

Chapter # 6: Denim washing

6.1 Introduction

6.2 How does washing create unique look

6.3 Processes involve in Denim washing

6.3.1 Dry process

6.3.2 Wet process

6.4 Types of denim washes

6.4.1 Chemical wash

6.4.2 Mechanical wash

6.6 Spraying

6.7 Whiskering

6.8 Softening process

6.9 Machine use for denim

6.10 New development toward economical and ecological denim processing

6.11 Value edition

Chapter 7

7.1 Conclusion

7.2 Reference

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' probably

came 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 we

will 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.



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 1960

the 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.



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.



• 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 barrel

with 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.

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 rebeaming operation, which will occur later. The yarns then go

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.



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.

2.2 COMPONENTS OF MACHINE

• Creel

• Rods

• Chain System

• Control Devices



• Sensors

• Head stock

• Expansion Comb

• Dust and fly accumulation unit

Showering assembly

2.3 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.

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.

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 – CH2 – 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.

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. They

usually 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

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



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



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

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.



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.



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]

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 increases

its dye uptake. It is then taken to a hot washing tank whose temperature is maintained at

850C. It is then taken to cold washing tank whose temperature is maintained at 600C.

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

Na2S2O4 + O2 + 2NaOH → Na2SO4 + Na2SO3 + H2O + C16H10O2N2Na2 + ½ O2 + H2O +

Sodium Hydrosulfide C16H10O2N2 + 2NaOH

Oxidized indigo

During 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.

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

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



and assembled on the weaving 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

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

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.

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.



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.



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

DENIM WEAVING:

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.


http://www.teonline.com/textile-machinery/rapier-loom.html

http://www.teonline.com/textile-machinery/shuttle-loom.html

http://www.teonline.com/textile-machinery/textile-weaving-machinery


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”

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 fabric

is 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

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.

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.

4.3 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

4.3.1 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.



4.3.2 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.

4.3.3 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.

4.3.4 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.

4.4 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

4.4.1 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 and

the 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.



4.4.2 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:

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

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 fabric

starts. 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

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 filling

density (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 the

loom (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 dent

can 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.

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

• 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

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

• improper working of solenoid valves

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.

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:



In this department dyed garment (denim) is scrabbled or brushed using Emery paper. 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. In this process whisker is

produce by using emery paper or rod (emery paper is wound on the rod).



GRINDING:

This process is use to get a worn look on the garment. Which 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.

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.

TAGGING:

It is a process which is use to get a unique effect by knotting the small areas of the

garment through tag pin by using tagging machine.

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.

Clip.

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

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 during

handling 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.


http://www.denimsandjeans.com/wp-content/uploads/2009/10/image12.png


Methods of Removing Sizes from Denim:

· Washing with High Alkaline agents ( i.e. Soda ash )

· Washing with High Acidic agents (i.e. Acetic acid )

· 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.

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



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.

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.

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

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:

It is done by tumbling the garments with pumice stones presoaked in a solution of

sodium hypochlorite or potassium permanganate for localized bleaching resulting in a

non uniform sharp blue/white contrast.

In this wash the color contrast of the denim fabric can be enhanced by optical

brightening. The advantage of this process is that it saves water as addition of water is

not required.

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

• 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.



6.4.2 MECHAINCAL WASHES:

1. Stone wash

2. Bio stone washing

3. Sand Blasting

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:



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.

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



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.

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:

Spraying is done after the brushing or scrapping process. In this process KMnO4 (so

called pinky) is sprayed via spray gun on to the garment.KMnO4 is work as a bleaching

agent which reduce the color or dye from the garment. It is also use for spraying Resin on

the garment to visible the whiskers different resin is used such as MKR and MIR. These

both resin are combined to form one resin which is then apply on the garment.



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



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)

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.



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

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



PROCESS RCIPE SHEET:



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).



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



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 is

done 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.

• 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 is

not 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

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.

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.

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.



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.



REFERENCES:

1. http://en.wikipedia.org/wiki/Denim

2. http://www.fashion-incubator.com/tutorials/warping

3. http://textilepedia.blogspot.com/2009/03/dyeing-process-for-denim.

4. www.thecompanymarketing.com/.../process-for-adding-value-to-denim


http://textilepedia.blogspot.com/2009/03/dyeing-process-for-denim

http://www.fashion-incubator.com/tutorials/warping

http://en.wikipedia.org/wiki/Denim

32212852 Denim Washing Thesis

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