Selection of denim fabric
The right selection of fabric can help minimise the cost of treatment and to solve environment related issues.
Different colour depth fabric: To cut processing time, effluent load, minimum damage to fabric and minimum use of chemical, there are different depth of indigo on denim. For example, in case of ice wash where we remove more than half the dye during washing, one can use lighter shade fabric which will help to cut the process time, chemical consumption, effluent load. It will help garment processor to process garment more economically and with minimum faults.
Flat look denim: Different chemicals and processes are used to get flatter look on the denim garments. To meet this requirement special denim fabric has been developed which offers flat look after washing.
Quick wash denim: Quick wash denim fabric is dyed with modified technique of dyeing, so that during wash cycle, indigo dye can be removed quickly, giving washed look at shorter washing cycle. This results in more economical washes i.e. low water consumption, less usage of chemicals, less time and retaining fabric strength.
Tinted denim: With increase in demand of tinted/ overdyed look on garment, garment processor is using an additional process of tinting/ overdyeing, which is time consuming. It consumes large quantity of water and chemicals. It is also associated with the risk of patches and unevenness on garments. Now the denim fabric is also available in tinted form which saves processors time and risk.
Grainy look denim: Different chemicals and processes are used to get grain look on the denim garments. To meet this requirement special denim fabric has been developed which gives grainy look after processing of denim garment.
Soft feel denim: To meet such requirement, different varieties of denim fabric are available, which are having inherent softness. These fabrics require minimum application of softener at the garment stage.
New developments towards economical and ecological denim processing
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. In one version of this concept, a mask is used to give the desired shape that is to be applied on the fabric. The laser projects through a lens system, which expands the beam. This beam is passed through the shaped mask that comprises an aperture of the desired shape and is then deflected by a mirror to strike the textile substrate. The duration of exposure determines the final effect on the fabric.
The novelty of this system is that
- It is water free fading of denim.
- It is an ecological and economical process.
- It can create local abrasion and fabric breaks, used look effect, moustache with excellent reproducibility and higher productivity.
- Being an automatic system, chances of human error are slim.
- The design is electronically translated on the fabric, thus avoiding the need for photolites of serigraphy cleaning.
The machine is very simple and compact, therefore requires very low maintenance and cleaning, extremely safe and reliable.
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.
Advantages of sand blasting process
- 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.
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.
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. 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.
Waterjet fading
Hydrojet treatment has been developed for patterning and/or enhancing the surface finish, texture, durability, and other characteristics of denim garment. Hydroject treatment generally 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. Particularly good results are obtained with blue indigo dyed denim.
As this process is not involved with any chemical, it is pollution free. By using water recycling system, the technique can be used as economical and environmental friendly denim processing. Color washout of dye in the striped areas produces a faded effect without blurring, loss of fabric strength or durability, or excessive warp shrinkage.
Spray techniques
This technique is based on spraying the chemicals or pigments to get different effect on the garments. This can be done by using robotic spraying gun or by manual spray and followed by curing of the garment.
- It a water free process therefore zero effluent discharge.
- Less time consuming
- Different designs are possible
- Easy to use
- No adverse effect on fabric strength.
Single bath stone washing and tinting technique
Tinting of denim garment is usually done after the stone wash process. In this, garment has been lightly coloured in order to give the final denim appearance a slight shift. This is not true over dyeing but merely gives the impression of a change in overall colour of the fabric. This process consumes large quantity of water and chemical. To make this process economical and ecologically friendly, some novel colour based enzymes have been introduced in the market. By using this new technique, tinting and stone washing effect can be achieved in a single bath.
- Less process time to achieve tinted look.
- No extra chemical required therefore making process more economical.
- Less water consumption.
- Less energy consumption.
- Less chance of patches or unevenness
Alternate of pumice stone
To overcome the shortcoming of pumice stones, synthetic stones have been developed. These are made of abrasive material such as silicate, plastic, rubber or Portland cement.
The advantage of using such type of products are:
- All major problems associated with the use of volcanic grade pumice stone can be overcome.
- Durability of such product is much higher and can be used repeatedly from 50-300 cycle depending upon type of synthetic stone.
- Reproducibility of washing is manageable.
- As stone discharge of the process is very less, therefore making process is economical and ecological.
- Less damage of machine and garments.
Waste water solution
As the municipal discharge criteria are restrictive and cost of water high, producers will need to reuse the waste water. Many techniques are readily available for a processor to treat waste water. The basic limitation of a garment processor is the higher installation cost associated with such techniques.
Technocrats need to realise that they have to develop simple and cost-effective garment processing technologies,
that aim at conservation of energy, water, time, and are environment-friendly.
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