Denim Jeans Manufacturing Process

Introduction:
Nowadays, without denim fashion is incomplete. No other fabric has received such a wide acceptance as denim in the history of textiles and it is the fabric of generations, worn by people of all classes and ages. It has an undisputed position in the fashion industry and its ability to adapt creatively to the fashion trends through its unique washing effects is incredible. It has been in use for over a century in the clothing industry, especially in the manufacture of overalls and trousers for hard labor, which has demonstrated its durability, which along with its comfort made denim jeans extremely popular for leisure wear, too. Denim is a hard wearing cotton twill fabric, traditionally woven with indigo dyed warp and white filling yarns. Denim jeans manufacturing involves the same classical principles which have been followed since its creation, but technological advances have transformed it into a highly fashionable material.

Originally, jeans were marketed and sold as workwear with primary emphasis on their durability and practicality. But when jeans were discovered and appreciated by consumers as general casual wear, they became fashionable and new techniques were developed to enhance denim garments and make them more unique. These techniques are popularly known as garment washing. Basically, all of these techniques involve the processing of garments in rotary drum machines.

The name ‘denim’ is thought to have its origins in the French word serge de Nimes, a fabric existed prior to the seventeenth century in the town of Nimes in France, while jeans seem to have their origin in a fabric made in the Italian city, Genoa. Later in the nineteenth century, the manufacture of copper riveted waist overalls out of denim by Levi Strauss in the US has laid the foundations of modern denim jeans. Ever since, denim has been in use in the clothing industry, initially in the manufacture of durable overalls and trousers for hard labor, which eventually identified itself as the hallmark of fashion wear. From the US, where it became the favorite of American cowboys, denim culture has now reached every corner of the world.

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The future of denim is secure as it has an ever growing fashion appeal internationally among all age groups. Somehow it remains eternally young in the hearts of generations and is now the fabric of choice for manufacturing anything that can be worn by anyone, anywhere, at anytime. It has also remarkable social and cultural influence and is considered as a symbol of teen rebellion, an expression of youth independence, an icon of heroism, and it reveals a different style and attitude towards life. This blue magic material has survived over a century and is an ever inspiring fabric for today and tomorrow. It still remains as the evergreen favorite of all and hence a future world without denim is unimaginable.

Maximum people think denim and jeans is same thing. Actually those are totally different things. Denim is the name of the fabric that is used to make jeans. We have also defined denim in above discussion. Jeans is one type of garment which is made by using denim fabric. Jeans is considered casual wear and worn by men and women outside workplaces. In this article I will explain denim and jeans manufacturing process in separately.

Manufacturing of Denim Fabric:
Denim, unlike many types of cloth (which are woven in one place and sent to another for dying), is woven and dyed at one location. As far as manufacturing process of denim is concerned, it is similar to that of Grey fabric up to the process of weaving with the only difference that in case of Denim Fabric, it is dyed at the stage of sizing where as in case of Grey Fabric, the decision regarding dyeing stage depends upon the finished product. Generally in denim fabric manufacturing cotton are used and in case of dye, indigo dyes are used for dyeing of denim fabric. In this article I will explain all process separately. Firstly is given manufacturing flow chart of denim fabric.

Flow Chart of Denim Production Process:

Yarn collection from spinning factory
↓
Warping
↓
Yarn dyeing
↓
Weaving
↓
Singeing
↓
Equalizing or Heat setting
↓
Finishing
↓
Inspection
↓
Folding & Packing
↓
Delivery

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Cotton Fiber:
Cotton is extensively used for denim jeans manufacturing, where the fiber quality and staple length are of crucial importance. Denim would not be denim without cotton, but the cultivation of cotton raises sustainability issues concerning the quantity of water and pesticides used. The use of organic or naturally colored cotton in denim manufacture can address the sustainability issues to some extent. Another possibility to reduce pesticide application is the use of genetically modified cotton. Cotton can also be blended with lycra, polyester, lyocell, wool, flax, hemp, etc. for developing special types of denim. Even though many such fibers are now entering the denim sector, it is highly improbable that they will ever replace cotton completely.

The cotton fiber needs to undergo a series of operations in order to be spun into yarns. Most of the cotton processing techniques for denim manufacture have not changed over the years. Unlike the weft, the production of warp yarn needs special attention, as it can influence the final quality of denim. Productivity and yarn quality are getting more importance in spinning, and in this respect, rotor spinning is becoming more prominent than the conventional ring spinning. Weaving a combination of ring spun and rotor spun yarns can help to reduce fabric costs while still maintaining some favorable ring spun fabric characteristics.

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Indigo Dye:
Indigo, which is otherwise a low quality dye, is widely used in denim dyeing, as it gives the characteristic blue color to denim. While the low fastness of the dye is a boon for achieving a distressed look, it leads to major effluent problems during the dyeing process and later in the washing of denim garments. Natural indigo has now been completely replaced by synthetic indigo, which seems to be more sustainable, but bio-synthesis of indigo would be really sustainable. A comparison of optimized natural indigo powder extracted from plants and optimized synthetic production shows that natural production of indigo may not be necessarily more environmentally friendly than the synthetic product.

At present, what raises concern is the reduction technique in indigo dyeing. The use of sodium hydrosulphite as a reducing agent is associated with several environmental issues. Commercially available pre-reduced indigo shows better fixation requires fewer chemicals and results in low effluent load. Alternate reducing systems have been explored, such as organic reducing agents, biological reduction, electrochemical reduction and catalytic hydrogenation of indigo.

Indigo Dyeing:
A unique feature of indigo dyed denim is the possibility of achieving wash down effects on repeated washing without losing the freshness of the color. Indigo dyeing is a vital step in the manufacturing of denim, and the warp yarns are dyed by either rope or slasher dyeing methods. The major issues in dyeing are the reducing agents and the huge volume of effluents, and quality control involves the monitoring of dye bath parameters like pH, sodium hydrosulphite and leuco indigo concentration, and the temperature of the dye bath. The pH is of crucial importance, as it controls the level of ring dyeing, and other important factors are the immersion time and number of dips.

Denim manufacturing is now faced with an eco-efficiency challenge with respect to sustainability. Several attempts have been undertaken in order to develop novel ‘green’ processes of denim dyeing, which should be more efficient, rapid, cheaper and easy to apply. One of the outcomes is the loop dyeing process, where the yarns are dyed in a single bath with one squeezing unit, after passing through the pretreatment boxes.

Non-indigo Dyes:
Non-indigo dyes, such as sulphur dyes, are now widely used in denim warp dyeing, and they offer vivid colors and a better ecological alternative to conventional indigo dyeing. Due to their better affinity for cotton, this dyeing is more efficient, and modern techniques can further reduce water usage considerably. Dyeing equipment, originally meant only for indigo, is undergoing transformation to provide the conditions required for the application of other dyes. Nowadays, the proportion of 100% indigo dyed denim warp is very small, as it is commonly combined with other types of dyes in the same application process, or overdyed with them. Sulphur dyes are widely used for bottoming and topping of indigo for reducing the overall cost.

Indigo will remain as the king of dyes and will stay associated with denim as its standard dye. But the demand from the fashion market could eventually activate much interest in non-indigo dyes, as they offer a full spectrum of colors. The permanent search for new effects and the flexibility that denim has for continuously reinventing itself will require exploring new application methods and developing new chemicals and dyes. A breakthrough dyeing process is Advanced Denim, which operates completely without indigo. It offers a great variety of colors, needs much less water and energy, and produces no effluents.

Denim Weaving:
Weaving is the final process in the manufacturing of denim and is very important in determining the quality of the final garment. Denim fabric is woven as 3/1 twill by the interlacement of indigo dyed warp and grey weft, and the yarn counts influence the fabric properties such as weight, fabric tightness, cover, drape, tensile strength and other properties. The weaving looms often used for denim are projectile, rapier and air jet loom.

Denim jeans manufacturing — Fig: Denim manufacturing

In general, the denim market is highly competitive and is driven by volume and not necessarily by the niches. So the success of denim weaving companies depends on aspects like process optimization and marketing profile. The possibilities include the use of engineered yarns, weaving denim efficiently in intelligent machines and using online quality control systems. All these could reduce energy consumption in weaving and also optimize material and resource efficiency. The industrial implementation of these technologies represents the future of denim weaving, which should be economically viable and will produce high quality denim.

Jeans Manufacturing Process and Finishing:
Denim jeans can be considered as the most widely used garment in the fashion business. It is well known that denim and jeans have had a major influence on the lives of consumers since their inception. Jeans have become symbols for cowboys, women, youth and economic status. Through the ages, jeans have evolved from workwear to casual wear and then to premium wear and functional wear.

stylish jeans pant — Fig: Stylish jeans pant (Photo: Shutterstock)

Consumers evaluate jeans based on style, brand, country of origin and company ethics. As with any other apparel, denim garment companies target specific market segments, however, no other garment can claim the social culture that denim has already set. Designer jeans as well as premium jeans first influenced a small group of luxury consumers, but now consumers from all social and economic classes embrace them. Challenges faced by denim apparel manufacturers and fashion designers include the need for reinventing products for niche markets, and meeting consumer demands for better apparel sizing.

We have already discus that denim is the fabric whereas jeans is the trouser that is made of denim cloth. Denim is used to make not just jeans but also shirts and skirts apart from many other accessories. Finally we can say all jeans are denim, but not all denims are jeans. Now I will discuss about denim jeans manufacturing process and firstly flow chart is given below.

Flow Chart of Jeans Manufacturing Process:

Denim fabric from batch
↓
Marker making with pattern
↓
Spreading
↓
Cutting
↓
Sewing or joining parts
↓
Washing (Enzyme wash, stone washing, bleaching wash etc)
↓
Finishing process
↓
Inspection
↓
Folding & Packing
↓
Delivery

Major segments of jeans manufacturing are discussed below:

Joining Techniques:
The stitching process gives birth to denim jeans, and the joining techniques are crucial in determining shape, fitting and style. The conversion of denim fabric into garments requires machines that are able to cope with the density of the fabric and the thickness of the seams. Therefore, heavy duty machines need to be used and specialized components have been developed to feed the material effectively through the machine. Other components such as heavy duty needles, sewing threads that have high strength for securing the seams, and buttons and studs for securing the pockets have been specially developed for this garment.

The challenges in joining include stress on the operators when stitching the material, due to its heavy weight and dense construction. This can create greater operator fatigue, and therefore sophisticated equipments to automate certain processes have been developed to reduce some of this fatigue and at the same time increase productivity.

Future trends in the joining of denim will be dictated by the developments in the material itself, environmental drivers and, of course, economic factors. The possible use of laser welding or soluble sewing threads that can be easily removed from a garment will allow for easier reconstruction of jeans into a new product.

Denim Garment Dyeing:
Denim garments, especially jeans, are manufactured from either indigo dyed denim or ecru denim. Ecru refers to undyed denim, and has the natural hue of cotton. Once the garment is manufactured, it can be dyed in different colors and shades as per the market need. It has some advantages over fabric dyeing, such as rapid manufacturing, quick delivery and reduced environmental impacts. There are basically two types of garment dyeing machines: paddle machines and rotary machines.

Garment dyeing has continuously evolved and adapted to changes in fashion, market needs and technological advances, and it seems to be moving towards implementing sustainable industrial practices. It can be considered sustainable since only the fabric used in manufacturing the garment is dyed and therefore there is no wastage of fabric or dyes. Further, the effluent load could be reduced by reusing indigo dye baths for shade development instead of using fresh dye baths. Natural dyes and environmentally friendlier reduction and oxidation systems for vat and sulphur dyes are also becoming important in denim garment dyeing.

Digital Printing of Denim:
Digital printing can be considered as an environmentally friendly technique for denim coloration, mainly because of the low quantity of colorant applied on the fabric, with less use of water and energy. It can also be applied in small lots, and a variety of designs can be created digitally on jeans. Similarly, laser engraving methods have several environmental advantages over chemical or mechanical washing techniques. So it is clear that digital printing and engraving present ecological and cost effective alternatives to conventional coloration and washing techniques.

More interestingly, digital printing provides the designers with more artistic freedom to creatively broaden their ideas. An unlimited variety of motifs and patterns can be developed and printed onto denim fabrics. This technology also enables creative designers and producers to work closely with retail distribution networks in real time, as a quick response model. The addition of electronic data interchange capabilities can materialize a concept known as fast fashion, and it can simultaneously boost the competitiveness of the company.

Denim Garment Washing Techniques:
Denim is actually a stiff and dull blue fabric without any fashion appeal, and washing is the revolutionary process that has changed this mundane image of denim. Denim garment washing is now an indispensable process for producing fashion items for leisure wear. Stone washing is the most important process, and it has innumerable variants now. Industrial washing machines play an important role, and depending on the market requirements, these machines can develop uniform color fading or appearance effects.

It is well known that denim garment washing depends greatly on the use of chemicals and stones for achieving the softening and color fading effects. As all these processes provide new looks by deliberately removing the dyes, they create an effluent problem, which brings into question the sustainability of the whole process. In this context, the denim washing industry is striving to develop environmentally friendly washing techniques that can result in zero effluent discharge. Dry treatments or nearly water free treatments are slowly becoming a sustainable trend for replacing traditional wet treatments in denim garment washing.

Enzyme Washing:
Enzyme washing can be used industrially for replacing or complementing the stone washing process. Ecological aspects are now becoming increasingly important in denim garment washing, and enzymes have contributed to improve the environmental profile of this process. The application of cellulase enzymes is well known to the majority of industrial laundries and the big brands and retailers are also very much aware of their sustainability aspects.

Effects of cellulase enzymes on denim:

In fading the desired effect is wash down look on the garment making the seams, hems, and pockets more prominent.
Other than look color contrast commonly known, as salt pepper effect is also one of the effects produced by fading. Faded garment with acid cellulase enzymes gives less color contrast as compared to garment washed with neutral cellulase enzymes.

The continuous research on new enzymes and formulations is going hand in hand with the innovation and sustainability strategies of leading fashion brands and laundries. Laccase enzymes can be used as an alternative to chemical bleaching where the enzyme oxidizes indigo to soluble degradation products. Thus there will be more and more applications for enzymes in denim garment processing, and the further optimization of existing enzymatic formulations or combining different processes will hold the key for efficient and sustainable washing.

The popular washed-down or worn look of denim jeans has usually been obtained by the use of pumice stones that are soaked in sodium hypochlorite or potassium permanganate (oxidizing agents). When jeans are tumbled with these stones, the dye is eliminated when the stones are rubbed against the fabric. Pumice stone washing has caused several problems, including rapid wear and tear of washing machines, a large number of second-class garments, unsafe working conditions, environmental pollution and the need for manual removal of pumice from pockets and folds of garments.

One of the best known applications of enzymes today is the bio-stoning or bio-stone washing, an alternative to stone washing on denim and other garments to give fading or vintage look. Cellulace enzymes can be used in place of pumice stones and achieve less damage to fabric, machinery and environment.

Reduced Water Washing:
It is high time for the denim garment washing industry to show that it cares for the environment and its operators. Thus there is a radical transformation taking place in this industry from an artisanal, labor intensive industry towards a knowledge based industry, caring for both the operators and the environment. New techniques like laser, ozone, etc., which use a much smaller quantity of water, are now changing the environmental profile of the whole washing process.

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These reduced water techniques are those that can obtain a washed look and excellent handle using a minimum quantity of water. The integration of such technologies into the conventional washing lines will ensure that vintage looks and other fashion effects can be created on jeans with much less water. In such cases, the effluent output is reduced to a negligible quantity, thus transforming denim washing to an environmentally friendly process.

Jeans Finishing Process:
Finishing of denim fabrics and jeans can provide aesthetic as well as functional properties. There are countless dry and wet processes in denim garment production to achieve fading, excellent handle and unique looks. Apart from such processes for achieving special fashion effects, several functional finishes can also be applied on denim garments for providing technical and functional properties. Microencapsulation, plasma techniques and nanotechnology are offering different possibilities that were not possible to achieve with normal finishing chemicals.

The functional finishes can create anti cellulite, odor resistant, wrinkle free, water/ oil repellent, mosquito repellent, antimicrobial, UV protection and flame retardant properties on denim garments. Thus denim, which is well recognized in the casual wear sector, is now finding new markets in technical textiles and non-apparel applications. More interestingly, many fashionable and multifunctional effects can be simultaneously created on denim garments.

Comfort Aspects of Jeans:
Cotton denim shows some sponginess, and in a highly humid atmosphere, it can assimilate a lot of moisture, causing discomfort to the wearers. This is because of the inherent character of cotton fabrics to wick well and to absorb moisture very easily. Apart from the fashion appeal, thermo-physiological and skin sensorial comfort properties are now becoming more important for denim garment users. The fabric structure and the types of fibers are the main contributors to thermo-physiological comfort.

The most established way to develop denim garments with better thermophysiological comfort is to manufacture denim with different fiber contents. As these blended fabrics are lighter in weight, they can dry rapidly, providing a warm feeling to wearers under highly humid conditions. The comfort can be further improved by applying moisture management finishes, which can transfer moisture away from the body by reducing the absorbent capacity and allowing faster drying. Cotton itself can be thus engineered to transfer moisture away from the skin to the outside of the denim, providing the wearer with a dry and comfortable feel.

References:

Denim : Manufacture, Finishing and Applications. Edited by Roshan Paul
Sustainability in Denim. Editors: Subramanian Muthu
Handbook of Value Addition Processes for Fabrics by B. Purushothama
Pretreatment of Textile Substrates by Mathews Kolanjikombil
https://textilelearner.net/denim-fabric-types-and-manufacturing-process/
https://www.denimsandjeans.com
http://www.fibre2fashion.com

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.