DENIM WASHING

Abinash MohantyAnurag SinghAvinash KumarDFT-4

INTRODUCTION OF DENIM…

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

Types of Denim

1. BUBBLE GUM DENIM (Lycra containing denim that has between 35 to 50% stretch)

2. COLOURED DENIM (fabric is woven with dyed yarn either warp or weft, It can also be obtained by Piece dyeing process.)

3. CRUSHED DENIM (Textured effect achieved through a special fabric construction coupled with wet processing, Fabric is woven with an over twist weft yarn, The effect can also be improved by bleach and stone )

4. DENIM FROM FOX FIBRE (Denim fabric manufactured by coloured cotton fibre that grows naturally developed and patented by California cotton breeder Sally Fox. NITRA, India has also done work on this line.)

5. MARBEL DENIM (It is an another name for acid wash, Some crushed denims, if strongly bleached, are also called marble.)

6. ECRU DENIM (The denim, which is not having dyed yarn i.e. only grey yarn in warp & weft.)

7. REVERSE DENIM (Where the face side and reverse side look alike.)

8. VINTAGE DENIM (A denim treatment that applies heavy stone washing or a cellulose enzyme wash with or without bleach for an old and worn outlook.)

BUBBLE GUM DENIM REVERSE DENIM

COLOUR DENIM

DENIM WASHING

• In denims, garment washing is done to produce effects like color fading with or without patchiness, crinkles, seam puckering, hairiness, de-pilling, softened-hand feel, stabilized dimensions etc.

• Denim washing is the aesthetic finish given to the denim fabric to enhance the appeal and to provide strength.

• Denim washing is known as one of the finishing treatment that has vast usage because of creating special appearance and updating clothes.

• There is different methods of denim washing.

Types of Denim Washing…

Denim washing are of two types.1. Mechanical washes• Stone wash• Micro sanding2. Chemical washes• Denim bleaching• Enzyme wash• Acid wash

Other mechanical washes-LASER TECHNOLOGY

SUPER STONEWASH

Scrubbing

Grindings-

grinding

Laser technology

Scrubbing

Tagging on pockets

RINSE WASH

Ozone fading

Over dye- tinting

Sun washing

Quick wash denim

Water jet fading

Vintage etc.

OTHER CHEMICAL WASHES

Stone Washing• This method is most

common and is used to give denim an 'old-look'.

• Pumice stone is one of the most important components used to abrade the surface of the fabric to obtain a surface pattern effect with color contrast and soft - handle.

• In this process, the fibres on the surface of the fabric are broken and removed and the inner white fibres of the warp yarn are gradually exposed.

• Natural patterns can be formed as the degree of abrasions varies in various parts of the garment.

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Selection of Stone• According to the end product

& effect required.• 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

Recommended Specification for Stones- • Moisture content-less than

5%• Surface properties-less

than 5% fines• Apparent Density-0.5-

0.75gm/cm3• Abrasion loss-35%• Impurities –

when exceed 10% they increase apparent density 1 gm/cm3, the stone will not float in water during process.

Stone Wash Cycle

• Loading of denim garment and stones• Desizing for about 15 minutes- Detergent plus

enzymes.• Rinsing • Stone wash- 30 to 60 min• Rinsing• Softening• Extraction• Unloading and removal of stones from garment• Tumble drying

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Limitations• Outcome of a load of jeans is never uniform.• Damage to wash machineries and garment due to

stone to machine abrasion.• Increase in labor to remove stone particles from

finished garments.• Water pollution during disposal of used liquor.

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MICROSANDING There are 3 ways for this

technique:- • Sandblasting • Machine sanding • Hand sanding or hand

brushing

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- 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

Used in Various Ways

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SAND BLASTING

• This technique is based on blasting an abrasive material (mostly sand) in granular, powdered or other form through a nozzle.

• It is purely mechanical process.

• It is a water free process.• Variety of distressed or

abraded looks possible.

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MACHINE SANDING

• In this fabric treatment process, a series of cylindrical rolls in a horizontal arrangement, either wrapped with an abrasive paper or chemically coated with an abrasive.

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HAND SANDING or HAND BRUSHING

• Use of sandpaper to abrade surface.

• Variety of looks and designs can be created.

Denim bleaching

• 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 is usually more apparent depending on the strength of the bleach liquor quantity, temperature and treatment time.

• Proper after wash or anti-chloring (incase of sodium hypochlorite bleaching agent) of bleached denim to minimize subsequent yellowing and tendering of denim.

Process Cycle of Denim Bleaching

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Limitations

• Process is difficult to control • Problem of yellowing • Required antichlor treatment • Causes corrosion• Harmful to human health • Source of environmental

pollution

Enzyme Washing

• This is a bio-catalytic method where in an ultra-soft handle effect can be produced on denim.

• The hydrolytic effect of enzymes causes the loss of surface fibre, which improves surface smoothness and softness of the fabric.

• Cellulase enzymes are natural proteins, which are used in denim garment processing to get stone wash look on to the denim garments without using stones or by reducing the use of pumice stone.

• Cellulase attacks primarily on the surface of the cellulose fibre, leaving the interior of the fibre as it is, by removing the indigo present in the surface layer of fibre.

ENZYME WASH CYCLE

• Loading of denim Garments (addition of Stones is optional)• Desizing with- alpha-amylase Enzyme, or- Oxidative desize• Rinsing• Adjusting pH to 4.5 to 5.0 with- acetic acid, or- buffer system • Heating to 50 to 60 C• Addition of cellulose enzyme• Tumbling for 30 to 60 minutes• Hot rinsing at > 65 C• Cold washing• Softening• Dry tumbling

Advantages • Prevents tendency of pilling after relatively short

period of wear. • Can be applied on cellulose and its blend. • Fancy colour-flenced surface can be obtained

without or a partial use of stone.• Soft handle• More reproducible results• Increased luster• Less corrosive• Less damage to seams

• Less wear & tear of machinery• Most economical due to more water

saving• Reduction in pollution, waste, quality

variation• Enzymes can be recycled unlike pumice

stones or acids• Reduce labour engagement

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Limitations• Garment load size of the machine is limited.• Post treatment required.

Acid Wash

• Acid wash can be carried on Indigo & Sulphur base fabric garments.

• Acid wash is a chemical wash on denim which stripped the top layer of color and make a white surface while the color remained in the lower layers of the material, giving it a faded look

• This wash is being carried out by pre soaking stones in bleach and then followed by neutralization.

• Acid wash of denim garment normally carried out by tumbling the garments with pumice stones presoaked in a solution which contains sodium hypochlorite (5 to 10%) or potassium permanganate (3 to 6%).

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Contd…

• Non-uniform contrast.• This finish gives indigo jeans sharp

contrasts. • The process is achieved by soaking

pumice stones in chlorine and letting these stones create contrast.

In this wash addition of water is not required. The color contrast can be increased by optical brightening treatment.

Acid Wash Garments

ACID WASH CYCLE• Loading of garment With pumice tones• Desizing for about 10 to 15 minutes• Drying • Dry tumbling for 10 to 30 minutes• Cooling without Addition of water• Per-oxide wash• Optical Brightening• Softening Treatment

Limitations:• 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 ethelene-diamine-tetra-acetic acid as chelating agent.

• Acid washing jeans avoided some of problems of stone wash, but came with added dangers, expenses, and pollution.

Acid Wash – Limitations & Remedies

References

1. www.fibre2fashion.com2. Denim garment washing process-ATIRA3. Denim garment processing –Express Textile(march 2003)4. Garment washing & finishing- Pearl Academy of Fashion 5. www.textileworld.com6. www.textileschool.com

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