Denim Washing – Basic Steps and Guide..

October 12th, 2009 by Saurabh | Filed under Manufacturing Process.

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Fashion is today incomplete without denim. Denim comes in all forms, looks and washes to match with every dress . It would be difficult to believe that the same denim was originally employed in clothing for the pants and overalls worn by miners on the west coast(US). A number of technological factors have contributed to making denim the fashion icon that it is today – including vast improvements in spinning, weaving, finishing etc. One of the most important part of creation of the beautiful denim jeans is the washing . Washing plays such an important part in the denim chain because of the umpteen effects that the consumers are looking for on their jeans . Lets talk a bit about denim washing …

 

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 results.

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
  4. Bleaching
  5. Tinting / Dyeing
  6. Softening & Much more…..

1.PRE TREATEMENT

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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 )

· 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

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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

Acidic &

Hybrid enzymes.

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 fabrics.

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 it.

3.CLEAN UP

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….

 

4.BLEACHING

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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 is sulphur top. As it takes longer time to give desired effect.

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:

1-Direct Dyes

2-Reactive Dyes

3-Pigment Dyes

4-Sulphur Dyes

Direct Dyes Reactive Dyes Pigment Dyes Sulphur Dyes

Economical

Costly

Cost Efficient

Economical

Wide range of shades

Wide range of shades

Styling ( limited to dull shades)

Shades are dull

Short Cycles

Long Cycle

Short to long Cycle

Short to long Cycle, depends upon shade

Ease of application

Water Consumption High

Machine contamination, but hard to obtain consistency, harsh hand feel

Sulphur Odour & harsh hand feel

Smooth Appearance

Smooth Appearance

Smooth Appearance

Smooth Appearance

 

5.SOFTENING PROCESS

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.

MINIMISATION OF YELLOWING RISK:

Its Impossible to eliminate yellowing but it is possible to prolong & reduce the conditions which causes classical yellowing:

· 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

 

Saurabh Pic (1) About the Author : Saurabh Rai  is a  Textile Chemist by Profession & Denim Finishing Expert .He is working in one of the most well known denim brand in Middle East as their denim washing head. Contact him on email here. Want to write guest articles ? Check here

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37 Responses to “Denim Washing – Basic Steps and Guide..”

  1. Bob Paluzi | 15/10/09

    Nicely done!

  2. Saurabh | 21/10/09

    @Bob Paluzi
    Hello Bob,

    Thanks for your feedback.

    Keep reading!

  3. Anand | 30/11/09

    Hi Saurabh,
    This is quite informative,would love to see dry process column as well. Cheers !!! Anand

  4. Saurabh | 6/12/09

    @Anand

    Hi Anand,

    Thanks for your valuable feedback, Here is the Link for Dry process Column, visit & let me know your feedback.
    http://www.denimsandjeans.com/denim/manufacturing-process/denim-dry-processing-for-creating-vintage-jeans/

    Cheers!!!
    Saurabh

  5. deepak. sharma | 25/02/10

    Hi Saurabh,
    This is very informative. thanks. Would also need to understand the role of the water (hard /soft) in the proccess of washing. Why is it that we are unable to create the finishes that we see in international brands which get the denims washed in Turkey, tunisia or romania.
    rgds
    Deepak.

  6. Reaz | 14/03/10

    Hi , Saurabh thanks for the nice and very helpful information about Denim washing. Would u please tell me that, how can i identify a denim fabric wheather it is acid , stone , or enzyme wash?

  7. Abinesh | 17/03/10

    Hi Saurabh Raj,
    Its a gd & useful artcl abt dnm wsh’g..txs..
    may i know the silicon sof & change in paramtrs, that can b usd w’out affect’g the hue/cast..
    abinesh.

  8. Abinesh | 17/03/10

    @Reaz
    Hi Reaz,
    i think i can share here..
    U NEED TO LOOK CLOSER ON THE WSHD GOODS..
    Stn Wshd – only raised warp gets abraded – surface abrasion..
    Enz Wshd – enzyme gets into the fibre as well – can see internal abrasion (white on) across the twill lines..
    Abinesh.

  9. muhit | 9/04/10

    Thank u for your work.It is helpful for me.Carry on good works.

  10. Raghu | 28/05/10

    hi Saurabh Raj,
    its was very interesting to read the article above it would be nice if u do the same on dry process as well
    nice work
    rags

  11. nurul islam | 9/06/10

    I want know special dry process chemicals & their
    application,could you pls write regarding this process?

    Tks

    nurul islam

  12. Pradeep Tanwar | 9/08/10

    hi sir it is very nice to see ur valuable advice on internet .
    want learn about it in my own city please guide me .

  13. krishna | 4/09/10

    what reaction in beetwin KMno4,cotton,and indigo and sulpher day/also i want to know about avery chemical which is use in textyle as oxidigingagent ?i hope,will you help me ?

  14. nobel | 9/09/10

    Dear Saurabh,
    I have been into denim designing since last seven years. Have spent so much time in laundries to achieve specific look. But the knowledge i have gained here is really helpful. Is there anyway i can get recipies for specific wash treatments.
    I am thinking of starting a small lab at home where i can experiment with different washes. Will be great if you can advice what kind of machine should i go for.

  15. shahid | 16/09/10

    Thanks for provide too/important information about denim.

  16. Nilesh Topiwala | 24/09/10

    Hi,

    I have a problem. I have denim being tinted to a light yellow. Its looks fab. Put it for washing at 30C the tint comes of 75% in one wash and completely on the second wash. My take is that the dyestuff has not be fixed properly and that direct dye has been used irrespective of the factory teling me its reactive they have used.

    Further they are trying to say

    The yellow tint is not coming off but is suppressed by the OBA in the detergent.

    I find this explanation totally unacceptable.Customer wouldnt buy a yellow tinted jeans if its going to be coming off in two washes. I have seen similar tinted jeans in the shops from other suppliers and i have washed them 9 times before it starts to fades.

    Any ideas. I believe the factory is trying to pull a fastone here.

  17. mahadevan | 30/09/10

    good one saurabh it was quite informative but s turned old but it will remain gold , v need to know some different process where all this process should be avoided means cut short process to save water, power, labours and time .

    ur this chapter should involve DRY process, wet process with coating ,printing of pu, etc

    I am sure u got what extra is required too.

    denim today is one off the creative segment and day by day u will find some or the other changes

    need to know the latest process

  18. Mamun -or- rasheed | 3/10/10

    Thanks for provide too
    important information about denim.

  19. duru | 24/10/10

    merhaba saurabh
    ben Türkiyede yıkama kimyasalları üretimi yapıyorum sizden oradaki yıkama fabrikaları hakkında bilgi almak istiyorum ürettiğim ürünlerle ilgili orada nasıl satış bağlantısı kurabilirim bilgilendirirseniz sevinirim
    iyi çalışmalar..

  20. duru | 24/10/10

    Hi Saurabh, I am doing in Turkey, the production of washing chemicals washing factories there, you would like to receive information about the link that I produced sales of products out there how can I how can I communicate with you

  21. Michael | 4/11/10

    Nicely explained!

  22. surya prakash sharma | 1/01/11

    I also want know that what are effects of water on denim? What type of water should be used while washing a denim after stitching? It should be soft water or hard water .Please explain.

  23. kazim | 26/01/11

    hi Rai
    hope u will b fine. i am also washing R&D expert working in Pakistan. i am textile engineer as well. i would appreciate you that u have taken up yur key time for sharing your knowledge and practical experience. this will really b helpful for students of textile engineering who have nt been to washing plants yet.

    good job

  24. raghu | 12/02/11

    Hi Saurabh, this was very informative article. I would like know detail step to follow the tint to get best results. plz help on this process

  25. Saurabh | 15/02/11

    Hi Raghu,
    If you are talking about direct dye tints, pls prepare a bath of tint , add tint ( Pr Diluted) in the bath run the garments & water for 2 to 5 min then raise temperature up to 60 degree celcius & run from Minimum 10 to 15 or 20 min by adding SALT to get exhaust the dyes. it depends on the type of Tint depth you needed.

  26. ahmed | 2/04/11

    sir i am a textile student and interested in denim washing so kindley send me the process and detailed information about denim washing as soon as possible you can thanks.

  27. Selvamani | 4/05/11

    Hi saurabh, very informative and useful.
    Can anything be done to correct the Denims that have yellow patches due to exposure.Have tried out treatment with Sod Meta Bisulfite, Peroxide.Although it is looking better still the patches persist.

  28. Rajib | 30/07/11

    Nice……………
    Dry Process pls…………

  29. Riaaz | 15/09/11

    I would like the feedback on the following fabric;
    Denim with spandex. please clarify what should be the ideal water temperature and Oven temperature so that elasticity is not lost

  30. Riaaz | 15/09/11

    Originally Posted By RiaazI would like the feedback on the following fabric;
    Denim with spandex. please clarify what should be the ideal water temperature and Oven temperature so that elasticity is not lost

  31. Tuhin | 13/05/12

    Really…amazing. I am also a wash technician …i cal learn more thing from here.

  32. Mustafa Naqvi | 22/05/12

    Very useful information

    Thanks

  33. Mustafa Naqvi | 23/05/12

    Nicely explained!
    Useful information, thanks for sharing this info

  34. Niranjan. | 23/05/12

    wants to know how to avoid STREAK MARKS,on denim while on
    washing.please foeword the process.

  35. Afif | 2/10/12

    Hi Sandeep, very informative, thank you. One question, Im washing a top sulphur dye garment and the metals(button, zipper, rivets) are getting a dark stain and making them dull. It is a simple wash process, just a normal desize, 20min neutral enzyme with a dosage of antiredep chemicals and a regular softening step at the end. Drying at low temperature has helped, but I need another option. What do you suggest to avoid the staining of the metals?

  36. Abdullah | 7/10/12

    Thanks for creating this outstanding website.
    it will help not only new learners but also experienced person in denim sector who is going to face far an interview!

  37. Denim Washing | 15/12/13

    Hi,

    I have a query for back staining in case of tinting. If we use any lining with denim shell fabric how will we protect them from tint or reduce able dyes from the shell, please give some instructions.

    For anti-bleaching agent to protect lining, can we use luccase bleach? please advise

    thanks
    http://textileaid.blogspot.com

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