1. Denim Washing Process
An overview of Denim washing process
The article is written by Saurabh Rai .
He is a Textile Chemist by Profession & a Denim Finishing
Expert .He is working in one of the most well known denim
brand in Middle East as their denim washing head
Pdf making by Hasan Chowdhury ,BUTex 37th Batch
2. BASIC DENIM WASHING PRINCIPLES
Below is the brief introduction to common steps done & followed in denim garments washing in
Laundries across the world. Different kind & make of machines being used across the globe to hit similar
Every small step in denim washing makes a big difference because indigo dye has very poor wet & dry
rubbing fastness. All parameters are critical to maintain for repetitive results. Eg Many laundries across
the Globe ignore the importance of pH M:L:R & R P M of machine.
Some important steps in the process of Denim Washing
1. Pre treatment ( Desizing, Rinsing, Scouring etc)
2. Enzyme or Stone wash
3. Clean up to adjust the desire effect
5. Tinting / Dyeing
6. Softening & Much more…..
This is very first & basic step but most important step of washing. Here the fate of denim garment is
decided that its going to appear good or bad. Good Pre treatments avoid streaking, stiffness & color
loss. This process removes impurities, starch & stains during handling of fabric.
This step is also called desizing ( Removal of Size applied during denim fabric making in weft yarn ). All
the woven fabric contains size on them due to reasons to strengthen the yarn for weaving.There are
many types of sizes available in the market but they can be divided in two major groups.
1. Water Soluble (CMC or PVA based sizes ) and
2. Dissolvable sizes in water ( Starch based ). Starch based sizes are most commonly used due to
cheap prices & readily availability.
Methods of Removing Sizes from Denim Jeans……
· Washing with High Alkaline agents ( i.e. Soda ash )
· Washing with High Acidic agents (i.e. Acetic acid )
3. · Washing with Oxidative chemicals ( i.e. Hydrogen Peroxide )
· Enzymatic desizing with Alfa amylase .. This is eco friendly & convenient .
2.Enzyme & Stone Washing Process Of Denim Garments
There are four kind of Enzymes available in market for Denim Laundry business..
• Amylase …. Desizing
• Cellulase …. For Salt & pepper effect , contrast
• Laccase…. … bio bleaching
• Catalase …… Peroxide killer
Enzyme is kind of protein that is obtained from fermentations method from naturally existing bacteria &
fungi. The structure of Enzyme is a biological polymer and it can be found in every cell. Generally called
as Cellulase & it works on cotton( Cellulosic fiber ) only. Enzyme are living organisms which will attack a
specific molecular group.
There are mainly three kind of Cellulase being used for Denim washing , Neutral, Acid and Bio polishing
Enzyme. Enzyme are very sensitive with parameters in washing cycle i.e, pH , Temperature & time. If any
of these parameters are not up to the mark, result will not be accurate.
The reaction of enzyme can be easily controlled, its biodegradable products, so they eco friendly.
Bio Polishing Cellulase are being used to have protruded fiber removal from denim & oven fabric. This is
also widely known as Anti pilling enzyme.
Any Cellulase used in process must be cleaned/killed after the process completion by simply disturbing
the parameters ie. By raising high temp. or raising pH to alkaline where no Cellulase withstand.
Cellulase are available in 3 categories
Neutral enzyme gives better salt & pepper effect with very less back staining & its generally come sin
powder form & also retains better strength of fabric than acidic Cellulase. Where as acidic cellulase give
faster results but with too heavy back staining & cuts down the indigo color, also affects the strength of
4. Now a days laundry people needs faster results in less time & money hence chemical suppliers
combined Neutral & acid cellulase in such way that it works faster & with better results than acid
cellulase with cost effectiveness & known as Hybrid enzyme.
Laccase is bio bleaching agent & alternative for conventional bleaching agents. This impart greyer cast to
blue denim & enhances salt & pepper effect. But due to high cost & low self life, laundries do not prefer
After finishing Enzyme wash it is must to add clean up process for better results & garments appearance
& that can be done in various ways & methods. As clean up is a must process to be carried out after
every chemicals steps done for any garments which allows next process to happen smoothly. All
processes mentioned below kill/ deactivate the active enzymes process which is necessary in order to
protect/retain garment strength……
• a.Hydrogen peroxide in alkaline pH clean up enhances the brightness & rich blue tone of indigo.
• b.By using non ionic detergents in medium to high temperature
• c.By doing two good hot water rinse etc….
This in one an important step in washing denim & can be done by various bleaching agents …..
• a.Calcium hypo chlorite
• b.Sodium hypo chlorite
• c.Hydrogen peroxide
• d.Potassium permanganate
First two chemicals are commonly being used for every medium to vintage denim but when it comes to
super vintage & light shade its advisable to use potassium permanganate bleach to cut the color faster
till half way & then neutralize it & go with Liquid ( Hypo ) bleach to adjust the desired shade.This
process helps to get Greyer cast & also protects the lycra/spandex , retain elasticity.
Hydrogen Peroxide is rarely used as bleaching agent when very less color loss required or if fabric
issulphur top. As it takes longer time to give desired effect.
5. Potassium Permanganate is also being used on 100% sulphur black denim fabric for bleaching/reducing
agent to get unique effects. As its not production friendly till laundry have very expertise team to handle
this program, otherwise it will result in many shades & cast.
Proper Neutralizations of bleaching process is very essential in order to get rid of fabric strength , bad
smell from garment, yellowing & skin irritation etc…
4.Tinting & Dyeing
Tinting is a process where very less amount of tint is involved & mainly direct dye is being used to do this
process. This is being done to change hue/cast/tone of indigo. As soon as quantity of tint color increases
& it cover up indigo, reaches the level of dyeing.
Tinting being used to give garments a used / vintage & muddy look. This process takes from 5 minutes
to 15 minutes time for better results followed by dye fixing & clean up of superficial dye.
Dyeing is being done on very light shade of Indigo, Ecru/ grey denim & Ready for dyeing denim.
• There are various Types Of Dye . THe comparison of these dyes is given in the chart herebelow:
Softening process of Denim is very critical. As denim is very heavy in compare with other fabrics hence
its needs softening. During this process there is a big problem -the discoloration of denim i.e change in
shade or loss of whiteness, giving a yellow tint is commonly known as yellowing. By using normal
softener will lead to ozone problem. Indigo dyed fabric are even more prone to yellowing.
As it’s a widespread problem & there in no single reason for its cause. Instead a number of condition can
singly or in combination lead to the problem. Yellowing in not specific to certain fibers, finishes or
washing processes. It is not specific to chemicals or chemical treatment but certainly some of the factors
among these can lead to the yellowing. As cotton & all organic polymers develop yellowing in time.
Light , acids, impurities, detergents & chemical contribute to yellowing problems.
Temperature of drying & curing can impart yellowing due to scorching of the cotton. Therefore good
control must be used to minimize this type of damage.
Hence its advisable to use Antiozonate softener which prolong ozone reaction of Indigo & keep garment
in good condition.
6. MINIMISATION OF YELLOWING RISK:
Its Impossible to eliminate yellowing but it is possible to prolong & reduce the conditions which causes
· Ensure bleaching neutralization & rinsing is proper
· Minimize back staining
· Avoid use of chemicals which cause yellowing
· Avoid leaving garment in open air for longer time
· Control drying & curing temperatures
· Using right Antiozonate softener with right pH
7. Denim Dry Processing For Creating Vintage Jeans
The distressed jeans that we see around everywhere undergo a wide variety of wet as well as dry
treatments to get the desired effects. Here I shall try to explain some basic Denim Dry Processing
techniques. In the creation of vintage denim jeans, dry processes play a very important role and hence
important to understand.
Denim Dry Processing – Basic know how
Destroying denims is as much an art as it is a technique. Details are added using a fine abrasive paper on
a scraping tool. And extra whiskering can be added with sand paper. Sometimes a bit of local tint
staining is being done into the local areas to emphasize the lighter parts. The jeans then go for a washing
with pumice stone to blend in the whiskering and tinting / over dyeing. Where the folds and wrinkles go
is where the art part comes in, it’s often through observation of where wear patterns are typically
found. For some of mine I have several pairs of old well worn thrift store jeans that I use as a
template to guide where I want the wear patterns. I chalk in where I want the details and then they are
finished off site by me in my finish workshop. Some of what is done to customize jeans are patented
secrets, no one other than those who work for these companies knows the exact techniques or the
abrasives and chemicals used to achieve certain special effects. Here I am revealing some basic facts to
the denimsandjeans.com readers……………..
Below is list of operations being carried out on denim garment to achieve VINTAGE (used/worn out)
• Hand Sand / Hand Scraping
• Sand blasting
• Knee Star / knee whiskers
• Hot Spot
• Damages / Destruction
• PP Spray
• PP Brush / towel
8. • Patch / repair
• Bleach spots
• Resin application
• Pigments & Local tint application etc…..
1.Denim Hand Sand / Scraping
Hand sand is step which is generally being done in rigid form of garments to get distress look. Locations
can be front thigh & back seat or its can be overall / global application as per Standard. Emery paper is
being used to scrape the garments in particular placement & design. Emery paper comes in different
number generally start from 40 till 600 and above , higher the number finer the emery paper, lower the
coarseness of the paper. In garment industry from 220 , 320 & 400 number papers are most popular &
Purpose of doing this process is make used worn out look to the garments.
The most important factor is to select right number of paper according to the fabric strength & intensity
need. Feathering / merging white sanded part to dark blue area in such way that it should look natural &
Scraping can be done on inflated rubber balloons for better effect ( horizontal or vertical its up to
operators convenience ) , even it can done plain wooden board of garment size & hand pressure should
be uniform in order to get better results.
Hand sanding must be started from intense part & feathering out on less intense part gradually. One
garment must by done by one operator only to have balance intensity on both the legs.
This process is isolated now a days due to health hazards & buyers do not like the results of sandblast
because its covers the characteristics of fabric. This process being done by using different kin d of sand
blown to garments with air pressure to rub out the color.
3.Whiskers/ Moustaches , Chevron , Knee Star, Hot Spot
On Denim, whiskers / Mustaches , Chevrons are nothing but the worn out lines / impression generated
by natural wearing on hip & thigh area. There are many designs & pattern available.
This is being done manually with help of sharp edge Emery paper rolled on fine wood stick or pasted on
plastic material. Before starting execution placements & pattern must be marked on garments, this will
help operator to execute the pattern right to match the aesthetics of garment.
Hot spots are heavy/intense area on thigh or knee which is made purposely to create used look & on
knee area if any whiskers line are there, called knee star.
9. All above operations are carried out in width direction hence its appears intense than hand sand with
less strokes, because hand sand is carried out in length direction.
4.Tacking & Grinding
Tacking: is a process which is being done by swift tag machine with the help of plastic or nylon tag pins
in rigid form of garment to get very heavy contrast ( rigid & washed ) on waistband, bottom hems, back
pocket & front pocket corners etc.. after completing wash cycle, it must be removed from garment
before making softening.
Grinding: is being done on pocket edges & bottom hems edges by running against abrasion surface or
stone to achieve worn out effect. Many different make of machines & pen grinding tools are available in
the market which runs with pneumatic system.
One of the most popular distressing effects currently , ‘Destruction’ is an art which make denim look
unique & used. To make destruction pen type of stone tools being used in mid of wash process to apply
on desired area. It can also be achieved by cutting it thru knife the warp yarns & keep the weft yarn as
is to show white thread. Holes also can be made by cutting weft & warp yarns. These are all manual
processes & every garment will look unique & different than others.
6.POTASSIUM PERMANGNATE SPRAY/RUB & BLEACH SPRAY
PP Spray is being done on denim garments to achieve local abraded area to appear whiter than back
ground indigo color shade. This can be applied by spray gun or by towel dipped in to PP Solution &
rubbed on desired area followed by neutralization in wet process. This process can be done in rigid after
doing hand scrape or in the middle of the wash. Doing after enzyme or bleach cycle will give more
natural & white effect that doing in rigid. There are many additives can be added in order to achieve
desired intensity and look.
The same way bleach solution also can be spray or rubbed on the garments on desired area. But this
process is very complicated & needs highly skilled operators to execute it followed by immediate
There are many parameters needs to be taken into control for doing PP or Bleach spray…. Spray gun
pressure, width of spray, flow & way of spraying.
Note:Safety of operators must be taken in to consideration and it must be ensured that he should wear
mask, gloves & eye glasses etc…
10. 7.Patch & Repairs along with Bleach Spots
These are totally manual processes to give uniqueness to Denim and to make it look VINTAGE.
First cut or damage the units intestinally to desired area & then make hand repairs or machine repair to
look natural. Diluted bleach can be used to spot the desired area followed by neutralization in wet
These process are time consuming hence productivity is low & reproducibility is very difficult but similar
aesthetics can be achieved.
When we talk about Vintage denim, every garment should look unique & not a photocopy !. These
garments are sold at very high prices so customer should have a feeling of uniqueness & feeling
different from others. Vintage denim are signature/ autograph of a brand & its image.
8.Resin Application( 3D Effect )
Resin ( Formaldehyde free ) being used for achieving 3D effect ( 3 Dimensional ), Rigid Look etc. This
process can be done by spraying or dipping the garments in to Resin, Catalyst, Silicone & PU solutionin
right combination according to the fabric strength & desired effect needed.
After application of resin solution in right proportion, make manual designing as needed on the thigh,
hip & back knee area to get 3Dimentional effect. After making it , it should be manually dried with hot
press or hair dryer & then must be cured in oven at right temperature, time as mentioned in resin
If resin not cured properly , 3 D effect will not be permanent & can cause skin irritation/rashes to the
wearer. Highly skilled operators needs to execute this process in order to get consistency & uniformity.
Whole garment can have crushed look by resin dip & crushed manually followed by oven curing.
Silicone plays an important role in getting softer hand after oven.
Special streaky effect & Crackles also being done by applying resin on desired area followed by scraping
& pp spray then neutralization.
9.Pigments & Local Tint ( Staining) Application
Need to choose right color of pigment or tint with binder or fixer to apply locally on denim to get
vintage look. This process also needs an artist to execute it nicely to merge the tint with ground indigo
color & should not look too artificial. Pigments & Local tint also can be applied through spray gun or
rubbing on desired area of denim garment. After application its must be cured in order to have
permanent effect on jean.
11. As we can see from all the dry denim processes mentioned above, they are mainly manual processes.
The quality of the worker can make or break the garment. Hence , great care has to be given to select
the right personnel for these jobs.
Compiled by : Hasan chowdhury
Butex 37 th ,Dept of Yme.