1.

Abstract:
In this assignment discussed about the manufacturing and flow process of denim from raw
cotton to finished garment jeans, dyeing of denim is done by the use of slasher dyeing
machines for the bulk production with higher number of threads. Different Method of
reduction of indigo, sustainable garment washing technologies for the purposes of fading and
mercerization process to make its excellent luster of jeans also discussed. Whisker and stone
enzyme wash process used for the washing to create this effect on denim and parameters
which should be checked after the process of dyeing also discussed.

2. Introduction:
2.1 Cotton fiber for denim:
Cotton fiber is the ideal choice for denim fabric manufacture due to its durability, strength and
comfort. Cotton has a high tensile strength, meaning that it can endure a lot of stress and wear
and tear, making it an ideal material for jeans. Cotton also has a unique texture and softness
that gives denim its signature look and feel, and it is also naturally breathable, which helps keep
the wearer comfortable. The yarn used to weave denim fabric is also made of cotton, and the
unique texture of the fabric is created by the weaving process. Without cotton, denim would
not be the same, as it would lack the unique texture, strength and comfort that make it so
popular.

Figure 1 cotton plant

Cotton can be blended with other fibers to produce unique and durable denim fabrics. Natural
fibers like wool, linen and hemp can be blended with cotton to create a lightweight, breathable
fabric that still retains the characteristics of denim. Synthetic fibers such as polyester, spandex
and elastane can also be used in combination with cotton to create stretchable denim fabric
that moves with the wearer. Blending different fibers also allows for different levels of comfort,
sustainability, durability and color. (Bajaj, 1999)
2.2 Indigo Dye for denim:
Indigo dye is the characteristic dye used to give denim its signature blue color. Indigo dye is
known for its lightfastness, meaning that it will not fade over time, making denim a durable and
long-lasting fabric. Indigo dye is also known for its color-fastness, meaning that it will not
transfer to other fabrics when washed. Furthermore, indigo dye has strong color saturation,
meaning that the blue color of denim will remain vibrant and intense, even after many washes.

Indigo dye effluent can be a major issue for the environment, as the dye is highly toxic and can
pollute soil and water sources.  Natural indigo dye is made from a plant-based source, while
synthetic indigo dye is created in a laboratory. Natural indigo dye has a softer, more natural
look and feel than synthetic indigo dye, and it is also more resistant to fading. However, natural
indigo dye can be more expensive and difficult to find than synthetic indigo dye. Synthetic
indigo dye is cheaper and easier to source, and it is also more resistant to water and fading than
natural indigo dye. (Etters, 1993)

2.3 Indigo dyeing:

One of the unique features of indigo-dyed denim is the way it fades without losing the
freshness of the color. With regular wear, the fabric fades differently in different areas, giving it
a unique, mottled look that many denim enthusiasts appreciate. This fading is also part of what
makes indigo-dyed denim so popular, as it gives the fabric a lived-in feel that can't be replicated
with other dyes.

Indigo dyeing is a popular method used to dye denim fabric. However, there are some issues
with this process that need to be addressed. The most important issue is the amount of water
and chemicals that are used in the process. The amount of water and chemicals used can cause
environmental problems such as water pollution, air pollution, and soil contamination.
Additionally, the toxic chemicals used in the dyeing process can be potentially harmful to
workers who are exposed to them. Finally, the indigo dyeing process can also be very
expensive, making it difficult for some manufacturers to afford. As a result, manufacturers may
be tempted to use lower quality dyes or chemicals, which can affect the quality of the fabric
and its color stability.

2.4 Denim weaving:

Denim is traditionally woven using a twill weave, which is a type of fabric weave that creates a
distinct diagonal pattern on the fabric's surface. This weave helps to create the classic look and
feel of denim fabric. Denim is also woven using a heavier thread than other types of fabric,
which helps to create its distinctive texture. The weave also helps to create the fabric's
durability and strength, making it ideal for use in clothing. The design of denim fabric is also
characterized by the use of indigo dye, which gives the fabric its signature blue hue. The dye
also helps to create a unique fading effect over time, which only adds to the fabric's appeal.
(Raina, 2015)

2.5 Manufacture and finishing of jeans:

In order to create a good luster and washing finish on denim jeans, manufacturers will use a
combination of processes. These processes can include stonewashing, enzyme washing, and
sandblasting. Stonewashing is a process where denim jeans are treated with pumice stones to
create a worn-in look. Enzyme washing is another process that is used to give denim jeans a
softer feel and a worn-in look. Lastly, sandblasting is a process that is used to create a
distressed look on the denim fabric. All of these processes help to create a unique and
appealing look on denim jeans.

3. Flow process in development of denim:

Cellulose fibers from cotton quickly became popular as a material for clothing, bedding, and
other products. By the 1920s, cotton cellulose was being used in the production of rayon and
other synthetic fibers. Rayon-based fabrics, such as rayon challis and rayon velvet, became
popular in the fashion industry during the 1930s and '40s. In the 1950s and '60s, scientists
developed new methods of producing cotton cellulose that allowed for the production of more
durable fabrics. This led to the production of fabrics such as polyester-cotton blends, which are
still popular today. (Gohl, 1983)

Today, cotton cellulose is used in a wide range of products, from clothing and bedding to
industrial filters and medical products. It has also been used in the production of bio plastics,
which are materials made from natural sources such as cellulose and starch. The history of
denim cotton dates back to the early 17th century, when it was first developed in Italy. It was
originally used as a sturdy, durable material for work wear, such as overalls and jackets. The
popularity of denim cotton spread throughout Europe and eventually reached the United States
in the late 19th century. In the early 20th century, denim cotton became the fabric of choice for
blue jeans, which quickly became popular among cowboys, miners, and laborers. The popularity
of denim jeans continued to grow throughout the 20th century and became a fashion staple in
the 1950s and '60s. (Paul, 1997)

Today, denim cotton is still a popular material for jeans and other clothing items, as well as for
home décor, upholstery, and other products. It is also used in the production of paper and
other products.

3.1 Cotton cultivation (growing and harvesting):

Denim cotton is a type of cotton that is used to make denim jeans and other apparel. It is a
high-yield, long-staple, and strong cotton variety. It is usually grown in warm climates and
requires a lot of water. When growing denim cotton, it needs to be watered a number of times
depending on how hot it is and how well the plant is growing. It can take more then 20,000L of
water to produce 1kg of cotton and it is important to have the right soil type, irrigation system,
and climate conditions. The soil should be well-drained and have a pH range of 6.5 to 8.0. The
irrigation system should be designed to provide uniform saturation and prevent water logging.
The ideal climate is hot and dry with temperatures ranging from 70-90°F.

For harvesting denim cotton, the plants should be cut when the bolls are mature and the seeds
are hard. The bolls should be picked when they are dry and the fibers should be extracted using
a comb or ginning machine. The fibers should then be carded and spun into yarn. (Khanpara,
2023)

3.2 Cotton fiber properties:

Cotton is a natural fiber that is strong and durable, yet lightweight and soft. Its fibers are hollow
and have a high tensile strength, making it a popular choice for use in clothing. Cotton is
breathable and absorbs moisture, which makes it a comfortable choice for clothing, especially
in hot weather. It is also resistant to mildew, bacteria, and other substances, making it an ideal
choice for use in medical products, such as bandages and gauze. Cotton is also highly
absorbent, making it a great choice for use in towels, bed sheets, and other household items.
Cotton is also relatively easy to dye, making it a great choice for clothing in a variety of colors.
Fiber consists of cuticle, primary wall, secondary wall and a lumen. In order to produce a finer
denim warp yarn, fine fibers of long staple length(28mm) are needed this will ultimately result
in a denim fabric that is smoother, soft and esthetically more pleasing to eye. (Zupin, 2010 )

Figure 2 : properties of cotton and other fibers

3.3 Cotton fiber processing:
Cotton fiber ginning is a process used to separate cotton fibers from the seeds and other
material in the cotton boll. The process involves the use of a machine called a gin, which is
composed of multiple revolving cylinders. The fibers are pulled through the gin, which uses a
combination of saws, teeth, and combs to pull the fibers from the boll. The gin separates the
fibers from the rest of the cotton boll, producing a light and fluffy material called lint. The lint is
then baled for shipment to textile mills for the production of fabric and other products. (Bajaj,
1999)

3.4 Opening, cleaning and blending:

Cotton fiber processing is the process of taking raw cotton fibers and transforming them into
usable fabric. This process begins with the opening and cleaning of the cotton fibers. During this
step, any contaminants such as dirt, seeds, and stems are removed from the fibers. The fibers
are then blended together to create a uniform sliver. The blended sliver is then passed through
carding machines, which use a series of metal combs to further clean, align, and interlock the
fibers. The fibers are then combed and drawn out into a thinner, more uniform strand. The
strand is then twisted together to create yarn. The yarn can be woven or knitted into fabric.
Finally, the fabric is washed, dyed, and finished to create the desired product.
 Figure 3 cotton processing stages

3.5 Spinning of denim yarn:

The yarn is typically spun using a traditional ring-spinning technique. This involves a spinning
wheel that has a ring-shaped groove around its circumference. The cotton fibers are fed into
the groove and spun into a yarn. The yarn is then wound onto a spool for further processing.
The spinning process helps to create a strong and even yarn with a unique texture. (Wulfhorst,
2006)
 Figure 4 Schematic view of the ring spinning process.

3.6 Rotor spinning of denim cotton:

Rotor spinning is a type of yarn spinning that is used to produce denim cotton yarn. This
process uses a rotor spinning machine and a unique spinning technique to spin yarn from the
cotton fibers. The yarn is then woven into denim fabric. The process involves feeding the cotton
fibers into the rotor spinning machine where they are spun and twisted together to form a
single yarn strand. The yarn is then wound around a bobbin and sent to the weaving machine
where it is woven into denim fabric. The denim fabric is then cut and sewn into jeans. This
process allows for a high-quality denim fabric that is durable and long-lasting. (Alagirusamy,
2010)

Figure 5 comparison of ring and rotor spun yarn

3.7 Warping of denim yarn (ball warping, beam warping):
Ball warping is a process used to make warp yarns for denim production. This method is widely
used to create warp yarns for denim fabrics. The process involves winding a continuous strand
of yarn from a single bobbin onto a large, rotating ball. During the winding process, the yarn is
twisted onto the ball in a manner that creates a desired pattern. Once the desired number of
turns has been made, the yarn is removed from the ball and sent to the weaving process.

Beam warping is another method of producing warp yarns for denim production. In beam
warping, the yarn is wrapped around a large beam, or cylinder, in a desired pattern. This
method is used to produce large lengths of yarn, as it can take up to 10 hours to produce a
single warp beam. Beam warping is the most common method used in denim production due to
its cost-effectiveness and its ability to produce longer lengths of yarn.

3.8 Slasher dyeing:

It is a unique method of dyeing jeans that results in a unique pattern. The dye is applied in a
slashing technique, which results in a light and dark pattern that is unique to each garment. This
technique is often used to create a vintage, worn-in look. The process involves first pre-treating
the fabric with a special agent that helps the dye penetrate the fabric more easily. After that,
the fabric is submerged in a vat of indigo dye and then slasher-dyed with a special device. This
process results in a unique, two-tone pattern that is unique to each piece.

Slasher dyeing is a one-stage production process that involves pre-treating the fabric with a
special agent to help the dye penetrate the fabric more easily, then submerging it in a vat of
indigo dye and slasher-dyeing it with a special device. This process is designed to be efficient
and streamlined, meaning that it can be done from back beam to weaving beam in one stage.
The fabric is treated and dyed in the same vat, and then the dyed fabric is sent directly to the
weaving beam for finishing. This eliminates the need for additional dyeing and finishing steps,
which helps to streamline the production process and reduce costs.
 Figure 6 slasher dyeing machine

3.9 Master technology machine for bulk production: (slasher dyeing)

Master Slasher dyeing machines for denim are advanced, automated dyeing machines designed
for bulk production. The machine uses a slasher dyeing method in which the fabric is fed into a
large hopper containing the dye, and then passed through a series of rotating jets which evenly
distribute the dye across the fabric. This method is especially effective for high thread count
fabrics, such as denim, as it ensures that the dye is evenly distributed across the fabric. The
slasher dyeing machines are also highly efficient, as they are able to dye large batches of fabric
quickly, and with minimal wastage. Furthermore, the machines are equipped with advanced
automated technology which allows for precise control over the speed, temperature and
pressure of the dyeing process. This advanced technology also ensures that the final product is
of the highest quality, making it ideal for mass production.

Figure 7 Master technology machine

3.10 Sizing of denim yarn after dyeing:

After dyeing, denim yarn may be subjected to a sizing process, which involves the application of
a coating to the yarn to reduce abrasion and fraying. The sizing material may be a combination
of resin, wax, oil, and other compounds. This process can provide additional strength and
stiffness to the yarn, as well as improved abrasion resistance and dye penetration.

3.11 Weaving for manufacturing of denim:

Weaving is a key component of the manufacturing process for denim. Denim is created by
weaving together two types of yarns, warp yarns and weft yarns. Warp yarns are set on the
loom before weaving begins and are held in place by the loom’s harness. Weft yarns are woven
through the warp yarns, creating a strong and durable fabric. The different weaving patterns
used to create denim fabric vary depending on the type of denim being produced. The most
common weaving pattern used in denim production is the twill weave, which gives the fabric its
unique diagonal lines. The twill weave also creates a softer, more comfortable fabric than other
weaving patterns. Other weaving patterns used in denim production include the plain weave,
basket weave, and herringbone weave. The type of weave used affects the color, texture, and
durability of the fabric.

3.12 Garments manufacturing and joining techniques of denim jeans:

Garment manufacturing of denim jeans typically involves the following stages:

I. Fabric Preparation: The fabric is prepared by preparing it for cutting, usually by washing
and drying it.
II. Pattern Cutting: The pattern pieces are cut out of the fabric according to the size and
style of the jeans.
III. Sewing: The pieces are then stitched together using sewing machines.
IV. Finishing: The jeans are then sanded and washed to create a vintage look.
De-sizing - Rinsing - washing(abrasion) - Rinsing - Softening - Drying
V. Joining techniques: The jeans are joined at the seams using techniques such as overlock
or flat-felled seams, topstitching and bar tacks.
VI. Final touches: Labels, rivets and other finishing touches are added to the jeans.

4. How will you ensure dyeing quality of yarns of denim so that the dyeing is
reproducible?
I. Use high-quality dyes that are colorfast and fade resistant.
II. Monitor the water temperature and maintain the same temperature throughout the
process.
III. Check the pH level of the water and maintain the same pH level throughout the process.
IV. Measure the amount of dye to be used and use the same amount for each batch.
V. Monitor the time taken for dyeing and keep the time constant for each batch.
VI. Set a standard procedure for the dyeing process and make sure that it is followed for
each batch.
VII. Perform quality checks throughout the process to make sure that the dye is evenly
spread and that the desired color is achieved.
VIII. Use the same dye bath for each batch and make sure that the dye bath is reused for
multiple batches.
IX. Use a reliable washing procedure after dyeing to make sure the color is fast and does
not bleed.
X. Document all measurements, procedures, and results to ensure that the dyeing process
is reproducible
5. What are the possible methods to reduce indigo dyes? Which one is more
sustainable?
Indigo dyeing for denim

Indigo dyeing for denim is a complex process that requires special attention and care to achieve
the desired look and feel. The process begins by preparing the fabric for dyeing, which involves
soaking it in a solution of salt and water and then rinsing it. The fabric is then scoured, which
helps to remove impurities and oils that may interfere with the dyeing process. Once the fabric
is prepped, it is ready to be dyed. The fabric is placed in a dye vat with indigo dye, and a
reducing agent is added to the vat. As the fabric is agitated, the indigo dye bonds to the fabric
and is reduced to a particular shade. This process is repeated until the desired color is achieved.
The fabric is then rinsed, dried and finished. The entire process can take anywhere from several
hours to several days to complete, depending on the type and weight of the denim being dyed.
Indigo popularity for denim has grown over the years due to the unique color and depth it gives
the fabric.

Reduction technique of indigo:

5.1 Fermentation or bacterial reduction:

Fermentation or bacterial reduction of indigo for denim is a process in which bacteria are used
to reduce the indigo dye to its insoluble form. This process is necessary to give denim its unique
blue color. During the process, the bacteria consume oxygen and produce lactic acid, which
helps to reduce the indigo molecules to its insoluble form. This process also helps to increase
the colorfastness of the denim fabric, which is important for a long-lasting denim look.

5.2 Chemical reduction:

The chemical copperas reduction method of indigo for denim is a process in which ferrous
sulfate (copperas) is used to reduce the indigo dye to its insoluble form. During the process, the
ferrous sulfate reacts with the indigo molecules, reducing them to their insoluble form. This
process helps to give denim its unique blue color, as well as increasing the colorfastness of the
fabric. Additionally, this process helps to increase the softness of the denim fabric, as well as
making it more resistant to staining and fading.

Hydrosulphite is commonly used to reduce the vat dye, indigo, to its leuco form. The reaction is
as follows:

Indigo + Na2S2O4 → Leuco-indigo + Na2SO3

The reaction is exothermic, and the resulting solution is blue-green in color. The leuco-indigo
can then be used as a dye itself or can be oxidized with air to regenerate indigo.

Reduction of indigo is a complex process that requires careful attention and precision, as the
results can vary greatly depending on the amount of time and reducing agent used. It is
important to follow the instructions of the dye manufacturer carefully in order to achieve the
desired results.

Figure 8 reduction of indigo

5.3 Electrochemical reduction:

The electrochemical reduction method of indigo for denim is a process in which electricity is
used to reduce the indigo dye to its insoluble form. During the process, a current is passed
through the indigo molecules, reducing them to their insoluble form.

5.4 Catalytic hydrogenation:

The catalytic hydrogenation reduction method of indigo for denim is a process in which a
catalyst is used to reduce the indigo dye to its insoluble form. During the process, the catalyst
reacts with the indigo molecules, reducing them to their insoluble form. This process helps to
give denim its unique blue color, as well as increasing the colorfastness of the fabric.
Additionally, this process helps to increase the softness of the denim fabric, as well as making it
more resistant to staining and fading.

5.5 Sustainable method of reduction of indigo:

Fermentation is a sustainable reduction method of indigo because it is a natural process that

does not require the use of harsh chemicals. The method allows for the breakdown of the
indigo molecule into its component parts, which can then be used to dye fabric in a more
environmentally friendly way. Fermentation is also a cheaper and more efficient method of
indigo production compared to other methods.

6. What parameters should be checked after dyeing of yarn?

 Colorimetric shade control
 Degree of ring dyeing

Colorimetric shade control is a method of ensuring that yarns are dyed to a consistent color.
This is done by measuring the color of the yarn with a colorimeter and then adjusting the
dyeing process to match the desired color. The degree of ring dyeing is a measure of the level of
dyeing achieved in the yarn. It is measured by examining the yarn under a microscope and
counting the number of dye rings per unit length. The higher the number of dye rings, the
higher the degree of dyeing.

7. Explain how you will attain luster on denim fabric:

To attain luster on denim fabric, you can use a combination of chemical and mechanical
processes. Chemical processes involve the use of special chemicals that are applied to the
fabric, which react with the dye molecules in the fabric to create a glossy finish. Mercerization
is a process used to attain luster on denim fabric. This process involves the use of a caustic soda
solution and a hot water bath to modify the yarn's surface. The caustic soda breaks down the
cellulose fibers in the fabric, making them more absorbent and increasing their luster. The hot
water bath helps to swell the fibers, making them more pliable and giving them a more lustrous
finish. This process is often used to give denim fabric a smooth and even finish, adding to its
visual appeal. Mechanical processes involve the use of machines that brush the fabric to create
a glossy finish. Additionally, you can also use waxing techniques, which involve using a waxing
iron to apply wax to the fabric, giving it a glossy finish. Finally, you can also use finishing
techniques that involve the application of a finishing solution to the fabric, which enhances its
luster.

8. Discuss garment washing technologies? Which one is more

sustainable and why?
8.1 Simple washing:
Simple washing is when denim is washed without the use of harsh chemicals or bleaching
agents. This process involves washing the denim in warm water with a mild detergent and no
additives. The denim is then air-dried or tumble-dried on a low-heat setting.
 Wetting-De-sizing-regular washing-softening

8.2 Bleach washing:

Bleach washing is a more aggressive process where the strong oxidative bleaching AGENT such
as Sodium hypochlorite (NaOCl) is added to the water used to wash the denim. This process
gives the denim a faded, worn-in look and feel. Bleach washing can also be used to create
unique patterns and designs on the fabric. It is important to take care when bleach washing
denim, as it can easily damage the fabric if not done correctly.

Garments loading with or without stone-De-sizing(10-15mint at 50-60 degree) - Rinsing-

Bleaching(10-15mint)-Rinsing-Bleaching with cold water-Optical brightening - softening

8.3 Stone washing:

Stone washing is a process used to give denim fabric a worn and faded look. It is done by adding
pumice stones to a washing machine with the denim during the washing process. The stones
are added in various sizes and ratios depending on the desired effect. The stones act as an
abrasive and wear away at the surface of the fabric to give it a softer, more worn-in look. The
longer the stones are left in the wash, the more pronounced the faded look will be. The size of
the stones and the ratio in which they are added will also affect the look. Larger stones will
create a more pronounced effect, while a higher ratio of stones will create a more intense
faded look.
8.4 Enzyme washing of denim:
Enzyme washing of denim is a process that uses enzymes to create unique textures, fades and
softness in denim fabric. This process is used to create vintage-looking denim garments with a
softer feel, and to give the garments a unique, one-of-a-kind look. The process involves soaking
the denim in an enzyme solution, and then washing it in a washing machine with special
detergents. The enzymes help to break down the fibers in the denim, creating a softer fabric
with a unique texture. The result is a garment that looks and feels like it has been worn for
years.

De-sizing (10-15mint)-rinsing - Enzyme washing(30-60mint, 50-60 degree with PH 4.5-5.5) -

Hot rinsing, e.g. 80 degree- Softening

8.5 Acid washing of denim:

Acid wash of denim is a process that uses a mixture of pumice and acid to create a unique look
and feel in denim fabric. The process involves soaking the denim in a solution of the acid and
pumice, and then washing it in a washing machine with special detergents. The acid helps to
break down the fibers of the denim, creating a softer fabric with a unique texture. The result is
a garment that looks and feels like it has been washed for years, with a unique faded
appearance.

De-sizing - soaking stones with strong oxidizing agent - draining excess liquor - dry tumbling
(10-15 mint) - rinsing to remove stone dust - rinsing with oxalic acid (in case of potassium
permanganate) - optical brightening - softening

8.6 Monkey wash of denim:

PP spraying - washing - treating with oxalic acid or Hydrogen peroxide to remove brown
manganese oxide

8.7 Sustainable washing technology:

The most sustainable washing technology for denim is laser technology. Laser technology uses
less energy and water than traditional chemical treatments, as well as reducing the amount of
chemicals used in the process. Additionally, laser technology produces less waste and requires
fewer resources to clean denim. The laser process is also more precise, allowing for greater
control over the finished product.

CO2 laser treatment of denim is a process which uses the energy of a CO2 laser to create
unique and customized designs on the denim fabric. The laser beam produces heat which is
used to cut and engrave the fabric, creating patterns, textures, and designs. The laser also
causes the denim to fade and distress, giving it a distressed and worn look. The laser treatment
is used to customize denim products and create unique designs, making them stand out from
the crowd

9. What will type of washing and/or dry process be carried to obtain

this type of effect?
Dry process

Whisker

Scraping
Taping

Washing

Stone enzyme wash

Hypo bleach

Neutral

Dry

Pp spray

Destroy

Neutral

Tint

Softener silicon