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DENIM

Denim is a sturdy cotton warp-faced[1] textile in which the weft passes under two or more warp threads. This twill weaving produces a diagonal ribbing that distinguishes it from cotton duck. The most common denim is indigo denim, in which the warp thread is dyed, while the weft thread is left white. As a result of the warp-faced twill weaving, one side of the textile is dominated by the blue warp threads and the other side is dominated by the white weft threads. This causes blue jeans to be white on the inside. The indigo dyeing process, in which the core of the warp threads remains white, creates denim's signature fading characteristics. THE HISTORY OF DENIMS A popular conception of the etymology of the word denim is that it is a contraction or derivative of the French term, serge de Nmes. Denim was traditionally coloured blue with indigo dye to make blue “jeans,” though “jean” then denoted a different, lighter cotton textile; the contemporary use of jean comes from the French word for Genoa, Italy (Gnes), from which the first denim trousers were made. A similarly woven traditional American cotton textile is the diagonal warp-striped hickory cloth that was once associated with railroad men’s overalls, in which blue or black contrasting with undyed white threads form the woven pattern. Hickory cloth was characterized as being as rugged as hickory woodnote to mention the fact that it was deemed to be worn mainly by “hicks “although neither may be the origin of that term [from a nickname for “Richard”]. Records of a group of New Yorkers headed for the California gold fields in 1849 show that they took along four “hickory shirts” apiece. Hickory cloth would later furnish the material for some “fatigue” pantaloons and shirts in the American Civil War.

INTRODUCTION

Denim is a rugged cotton twill textile, in which the weft passes under two (twill- “double”) or more warp fibres, producing the familiar diagonal ribbing identifiable on the reverse of the fabric.

               The name "denim" derives from French serge de Nîmes, meaning 'serge from Nîmes'. Denim was traditionally colored blue with indigo dye to make blue jeans, although "jean" formerly denoted a different, lighter, cotton fabric. The contemporary use of the word "jeans" comes from the French word for Genoa, Italy (Gênes), where the first denim trousers were made.  Denim has been used in the United States since the mid 19th century. Denim initially gained popularity in 1873 when Jacob W. Davis, a tailor from Nevada, manufactured the first pair of rivet-reinforced denim pants. At this time, clothes for Western laborers, such as teamsters, surveyors, and miners, were not very durable. His concept for making reinforced jeans was inspired when a female customer requested a pair of durable and strong pants for her husband to chop wood. When Davis was about to finish making the denim jeans, he saw some copper rivets lying on a table and used the rivets to fasten the pockets. Soon, the popularity of denim jeans began to spread rapidly and Davis was overwhelmed with requests. He soon sold 200 pairs to workers in need of heavy work clothing. Nevertheless, because of the production capacity in his small shop, Davis was struggling to keep up with the demand. He then wrote a proposal to dry goods wholesaler Levi Strauss & Co. that had been supplying Davis with bolts of denim fabric. Davis's proposal was to patent the design of the rivet-reinforced denim pant, with Davis listed as inventor, in exchange for certain rights of manufacture. Levi Strauss & Co. was so impressed by the possibilities for profit in the manufacture of the garment that they then hired Davis to be in charge of the mass production in San Francisco. 

TYPES OF DENIM

=

Dry or raw denim

Selvedge

Dyeing

Coloured denim

Stretch denim ===

BoldDry or raw denim

Dry or raw denim (contrasted with "washed denim") is denim that is not washed after having been dyed during production. Dry denim will fade, considered fashionable in some circumstances. During the process of wear, fading will usually occur on those parts of the article that receive the most stress. On a pair of jeans, this includes the upper thighs, the ankles, and the areas behind the knees. After being made into an article of clothing, most denim articles are washed to make them softer and to reduce or eliminate shrinkage (which could cause the article to not fit properly after its owner washes it). In addition to being washed, "washed denim" is sometimes artificially distressed to produce a "worn" look. Much of the appeal of artificially distressed denim is that it resembles dry denim which has faded. In jeans made from dry denim, such fading is affected by the body of the person who wears them and by the activities of their daily life. This process creates what many enthusiasts feel to be a look more "natural" than artificially distressed denim. To facilitate the natural distressing process, some wearers of dry denim will abstain from washing their jeans for more than six months. Most dry denim is made with 100% cotton and comes from several different countries. In particular, the United States, Zimbabwe and Japan are popular sources of cotton for making raw denim. Dry denim also varies in weight, typically measured in by the weight of a yard of denim in ounces. 12 oz. or less is considered light denim, 12 oz. to 16 oz. is considered mid-weight and over 16 oz. is considered heavyweight. Heavier denim is much more rigid and resistant to wear, but can also take a larger number of wears to break in and feel comfortable. Patterns of fading in jeans caused by prolonged periods of wearing them without washing are a way of "personalizing" the garment. These patterns have specific names: • combs or honeycombs – meshes of faded line-segments that form behind the knees • whiskers – faded streaks that form radially from the crotch area • stacks – irregular bands of fading above the ankle caused by according of the fabric due to contact with the foot or shoe • train tracks – fading along the out-seams due to abrasion

Selvedge

• Denim jeans showing the selvedge of the fabric joined to make a seam • Selvedge (or selvage) is the edge of a fabric as it comes from the loom. Selvedge are woven or knit so that they will not fray, ravel, or curl. • Selvedge denim refers to a unique type of selvedge that is made by passing one continuous cross-yarn (the weft) back and forth through the vertical warp beams. This is traditionally finished at both edges with a contrasting warp (most commonly red); that is why this type of denim is sometimes referred to as "red selvedge." This method of weaving the selvage is possible only when using a shuttle loom. • Shuttle looms weave a narrower 30-inch fabric, which is on average half the width of modern shuttle less Sulzer looms. Consequently, a longer piece of fabric is required to make a pair of jeans from selvedge denim (approximately three yards). • To maximize yield, most jeans are made from wide denim and have a straight out seam that utilizes the full width of the fabric, including the edges. Selvedge denim has come to be associated with premium quality jeans, which show the finished edges from the loom rather than the over locked edges that are shown on other jeans.[10]

Dyeing

Denim was originally dyed with a dye produced from the plant Indigofera tinctoria, but most denim today is dyed with synthetic indigo dye. In both cases, the yarn undergoes a repeated sequence of dipping and oxidation — the more dips, the stronger the colour of the indigo. Rope dyeing is considered the best yarn-dyeing method, as it eliminates shading across the fabric width. The alternative "slasher process" is cheaper because only one beaming process is needed. In rope dyeing, beaming is done twice. Coloured denim Denim fabric dyeing is divided into two categories: indigo dyeing and sulphur dyeing. Indigo dyeing produces the traditional blue colour or shades similar to it. Sulphur dyeing produces speciality black colours and other colours, such as red, pink, purple, grey, rust, mustard, and green. Stretch denim Stretch denim incorporates an elastic component, such as spandex. This creates a certain amount of "give" in garments made from stretch denim. Only a small percentage (about 3%) of spandex is required within the fabric to create a significant stretching capacity of about 15%. However, this feature will shorten the wearing life of the garment.

Uses

Clothing • Boots and athletic shoes • Capri pants • Dresses • Hats • Jackets • Jeans • Overalls (dungarees) • Shirts • Shorts, including Daisy Dukes and cut-offs • Skirts • Sneakers (Kids, Converse Chuck Taylor All-Stars) • Suits Accessories • Belts • Handbags (purses) • Tote bags Furniture • Bean bag chairs • Lampshades • Upholstery

DENIM WASHING

Denim washing is the aesthetic finish given to the denim fabric to enhance the appeal and to provide strength. Dry denim, as opposed to washed denim, is a denim fabric that is not washed after being dyed during its production. 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.

DENIM WASHES:

Mechanical washes

Stone wash

Micro sanding

Chemical washes

Denim bleaching

Enzyme wash

Acid wash

CHEMICAL WASHES

Denim bleach: 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 anti-chloride or after washed with peroxide to minimize yellowing. Materials should be carefully sorted before processing for colour uniformity.

Process cycle:

Limitations: 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 are 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 colour 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 cellulose making the seams, hems, and pockets more noticeable

2. Salt pepper effect is colour contrast effect.

3. Faded garment with acid cellulose enzyme provides less colour contrast in proportion to garment washed with neutral cellulose enzymes.

Garment load size of the machine is 35-40 jeans per machine and it cannot be overloaded.

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 colour 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.

Remedy:

Manganese is effectively removed during laundering with addition of ethylene-die-amines-tetra-acetic acid as chelating agent. Acid washing jeans avoided some of problems of stone wash, but came with added dangers, expenses, and pollution. MECHANICAL WASHES

Stone wash:

            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

          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:

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 or Re-deposition:

The dye removed from denim material after the treatment with cellulose or by a conventional washing process may cause “back staining or “re-deposition. Re-coloration of blue threads and blue coloration of white threads, resulting in less is 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

Micro sanding

There are 3 ways for this technique:

1. Sandblasting

2. Machine sanding

3. Hand sanding or hand brushing

Used in various ways:

        Flat surfaces (tables, ironing boards)

On the dummy (inflatable dummies, sometimes standing, sometimes flat, sometimes ‘seated’) Various templates can be used to create a 3D effect.

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.

WHISKERING

Also known as Cat’s Whiskers 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)

Other chemical washes:

Rinse wash Cellulose wash Ozone fading Snow wash Salt water denim Flat finish Over dye Sun washing Super dark stone

RINSE WASH

        Chemically bleaching jeans so that the colour fades away.

Breaks down the fibres of jeans and creates white streaks or spots on denim Gives a unique rugged look, also called snow wash Earlier involved the use of pumice stone Presently process involves spraying chemical and removing it immediately Come in colours like blue, black, green, brown, grey etc.

CELLULOSE WASH

This is done to achieve a wash down appearance without the use of stones or with reduced quantities of stones. Cellulose enzymes are selective only to the cellulose and will not degrade starch. Under certain conditions, their ability to react with cellulose (cotton) will result in surface fibre removal (weight loss). This will give the garments a washed appearance and soft hand.

Factors influencing cellulose performance

pH Temperature Time Dose Mechanical action

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. In the presence of UV light, there is an interaction between the hydrocarbons, oxides of nitrogen and oxygen that causes release of ozone. Indigo dyestuff tends to fade or turn yellow due to ozone reaction.

The advantages associated with this process are:

Colour 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.

FLAT FINISH

It is a special process done to impart fabric with an even wash down effect and very clean surface. Originally liquid ammonia was used, but now uses mercerization plus calendaring processes to achieve the flat surface.

Mercerization swells up the cotton fibres and allows the calendaring to press flat the surface.

They consider this as an imitation process to the use of ammonia, which is toxic and not allowed in commercial use in most countries

OVERDYE

Dyeing over the fabric or jeans to add another tone of colour Most often used is a ‘yellowy’ over dye to create a ‘dirty’ look Also can be applied with spray gun or paintbrush for local colouring SUNWASHING

A very light shade by bleaching and stoning Looks as if the sun faded the fabric

SUPER DARK STONE

Commercial term for an extra dark indigo colour Results from a double-dyeing technique

SNOW WASH DENIM

          Denim treated with a variation of acid wash that imparts bright white highlights.

QUICK WASH DENIM

           Aims at minimizing wash cycle time

Results in more economical washes and solving many other washing problems faced by launderes during fashion wash cycles The yarns are ring dyed using indigo giving 25 to 30% less fixed dye to obtain a given shade During wash cycle, indigo dye can be removed quickly, giving washed look

Advantages of quick wash denim

          1. Streaks develop in garments after washing process due to differences in dye concentration of denim fabrics are avoided using a modified alkali-ph controlled system giving uniformity of shade.

2. Amount of indigo dye required is less thus making it an economical process

3. Time required for washing is 20-30% less than that required for conventional denim.

4. Lesser enzymes and oxidising agent used

5. Environment friendly process

6. Back staining is minimised due to less concentration of of indigo dye in the wash liqour.

Other Mechanical washing

Whickering

Shot gun denim

Water jet fading

Super stone wash

Ice wash

Thermo denim

Laser technology finish

WATERJET FADING

      Hydro jet treatment is used for enhancing the surface finish, texture, durability of denim garment.

Hydroject treatment involves exposing one or both surfaces of the garment through hydrojet 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. As this process is not involved with any chemical, it is pollution free.

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. It is water free fading of denim. Being an automatic system, chances of human error are slim. Also called spray painting in denims. This technique has relatively high cost.

SUPER STONEWASH

Prolonged stonewashing, Up to six hours or more.

ICE WASH

      Ice washing in denim fabrics is done to remove more than half the dye during washing

THERMO-DENIM

        Also called double denim. A lightweight fabric (either plain, fancy or coloured) is glued to the denim. The glue comes off after washing and the trousers look like they’ve been lined

VINTAGE

        Applies heavy stonewashing or a cellulose enzyme wash, with or without bleach

Gives an old and worn look

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. Indigo fix 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

CONCLUSION

Denim is unique in its singular connection with one colour. The warp yarn is traditionally dyed with the blue pigment obtained from indigo dye. Until the introduction of synthetic dyes, at the end of the 19th century, indigo was the most significant natural dye known to mankind, linked with practical fabrics and work clothing. The durability of indigo as a color and it’s darkness of tone made it a good choice, when frequent washing was not possible.

The old mass market has segmented, fragmented, shattered into a multitude of mini, micro and niche markets. The last generation has a vast quantity of brands to choose from, a different perception of the cult value of owning small insider labels and a fanatical loyalty only to what’s hot on a daily basis.

Freed of all social and creative restrictions, denim is assuming any number of disguises and contexts to be worn in and has broken through almost any limitation on price. It can also be found in home collections, appearing in cushions, bed spreads and furniture-coverings.