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1. Mechanical washes - Stone wash

- Microsanding 2. Chemical washes - Denim bleaching - Enzyme wash - Acid wash

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.

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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.

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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 and re deposition.

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 "redeposition”. 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

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STONEWASH EFFECT:

In traditional washing process, volcanic rocks or pumice stones are added to the garments during washing as abradant. Due to ring dyeing and heavy abrasion fading is more apparent but less uniform.

The degree of colour fading depends on the garment to stone ratio, washing time, size of stones, material to liquor ratio and load of garments. Normally after desizing, stone wash process starts with pumice stone addition in rotary drum type garment washer. Process time varies from 60-120 mins.

Stone wash effect is one of the oldest but highly demanded washing effects. Stone wash process gives “used” look or “vintage” on the garments, because of varying degree of abrasion in the area such as waistband, pocket, seam and body.

There are many limitations and drawbacks associated with stone washing process, which can be overcome by using new enzyme based washing technology. This technology also helps to conserve water, time, energy and environment.

MICROSANDING

There are 3 ways for this technique:

• Sandblasting

• Machine sanding

• Hand sanding or hand brushing

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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.

MECHANICAL ABRASION

To give worn out effect, abraded look or used look, some mechanical processes have been developed. These are based on mechanical abrasion by which the indigo can be removed. Some of these processes are sueding, raising, emeresing, peaching and brushing.

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Advantages of these processes:

- Control on the abrasion

- Different look on the garment can be achieved.

- All are dry process.

- Economical, ecological and environmental friendly.

Other Mechanical washing

 Whiskering

 Shot gun denim

 Water jet fading

 Super stone wash

 Ice wash

 Thermo denim

 Laser technology finish 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)

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WATERJET FADING

- Hydrojet 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.

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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 colored) 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

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