garment processing: The eco-friendly way
domestic readymade garment sector is booming, and garment processing
has emerged as one of the important production routes towards meeting
quick changing demands of the fashion market. In this article we
look at processing of denim garments.
of garment processing
Increases the opportunities available for differentiation of the
Offers option to retailer, which are not available in piece good
Gives opportunity to impart unique looks and finishes that cannot
be achieved in fabric form.
It allows to hold colour and finishes until the last minute and
enables you to shorten the time to market.
spread of denim culture, all over the world brought with it a trend
of fast changing fashions. One after another, several washes were
introduced such as stone wash, acid wash, moonwash, monkey wash,
show wash, frosted wash, white wash, mud wash, etc. Over the last
6-8 years, India has probably seen the most dramatic and exciting
changes in the washing of denim garments.
Traditional desizing is performed by using acid or oxidative desizing
agents which is associated with many drawbacks and limitations.
Due to uncontrolled and non-specific reaction, the cellulose material
gets damaged and looses strength. With the introduction of enzyme
based desizing process, the limitation and drawbacks of traditional
desizing process can be overcome. The enzymatic desizing process
is performed by using alphaamylase enzyme.
of enzymatic desizing over traditional desizing
Due to very specific reaction of enzyme, there is no adverse effect
on cellulose, therefore better strength retention.
Saving of water as multiple washing is not required to remove the
residual chemicals after desizing.
Process time of desizing can be reduced.
Neutralisation is not required because same processing conditions
are required in next process therefore zero salt formation in ETP.
Saving of energy as desizing takes place at moderate temperature.
Feel of fabric is much softer and less hairiness on the fabric.
No adverse effect on other bath auxiliaries due to mild process
No adverse effect on Lycra or polyester containing fabric.
Handling of chemical is safe and easy.
No adverse effect on machinery.
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.
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.
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.
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.
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 is classified into two classes:
Acid Cellulase: It works best in the pH range of 4.5-5.5
and exhibit optimum activity at 50.
Neutral cellulase: It works best at pH 6 however its activity
is not adversely affected in the range of ph 6-8 and show maximum
activity at 55 C.
of enzyme washing
Soft handle and attractive clean appearance is obtained without
severe damage to the surface of yarn.
Inexpensive, low-grade fabric quality can be finished to a top
quality product by the removal of hairiness fluff and pills, etc.
Simple process handling and minimum effluent problem.
Better feel to touch and increased gloss or luster.
Prevents tendency of pilling after relatively short period of
Can be applied on cellulose and its blend.
Due to mild condition of treatment process is less corrosive.
Fancy colour-flenced surface can be obtained without or a partial
use of stone.
More reproducible effect can be obtained.
It allows more loading of the garment into machines.
Environmental friendly treatment.
Less damage to seam edges and badges.
Wear and tear of equipment is minimum due to absence of stone.
Use of softener can be avoided or minimised.
Easy handling of floor and severs as messy sludge of stones does
Due to absence of stone, labour intensive operation of stone removal
is not required.
Homogenous abrasion of the garments.
Puckering effect can also be obtained.
Problem of pumice powder contamination on garment is not there.
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
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 they cause severe environmental
Bleaching concept for denim
research is underway for the development of sodium hypochlorite
bleaching alternative eg, glucose bleaching, bleaching with sulphinic
acid derivatives, and recently with laccase (enzyme).
enzyme belongs to the oxidoreductase group. Laccases oxidative
effect is complex, it does not work independently. A mediator is
necessary and a chemical mediator is employed between enzyme and
New Laccase based bleaching technique only affects the indigo
and natural raw white of weft yarn is retained, giving the woven
fabric a darker shade, which is not implicitly achieved with hypochlorite
The product is so specialised on indigo that it does not attack
any other dyes.
Laccases open up the door to bleach Lycra containing denim without
loosing the strength of the fabric. In case of hypochlorite bleaching
Lycra containing product affects adversely by loosing the tear
and tensile strength.
Finally the process is based on enzyme so no risk of environmental
pollution and harmful effluent discharge.
Expensive, compared to traditional process.
Heavy faded look is difficult to achieve.
use of an engineered oxidatively stable alkaline protease that can
tolerate a range of operating temperature and pH conditions offers
flexible and alternative processes for backstaining clean-up, improved
contrast of denim finishes, and reduced residual cellulase of fabric.
is claimed that significant reduction in backstaining can be achieved
at much lower temperature than conventional process by using small
amount of protease either at the end of the cellulase washing step
or during the rinsing step. By adding the protease at the end of
the cellulase wash step, one rinse step is eliminated offering savings
in time and energy. This process at lower temperature also claims
to achieve a significant reduction of residual cellulase.
of denim fabric
right selection of fabric can help minimise the cost of treatment
and to solve environment related issues.
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
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.
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.
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.
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.
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
developments towards economical and ecological denim processing
of laser technology
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.
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.
machine is very simple and compact, therefore requires very low
maintenance and cleaning, extremely safe and reliable.
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.
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.
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.
of these processes:
Control on the abrasion
Different look on the garment can be achieved.
All are dry process.
Economical, ecological and environmental friendly.
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
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
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.
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.
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
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.
bath stone washing and tinting technique
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
of pumice stone
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.
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.
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.
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.