Latest Dry Washing Techniques in Denim Garments (Part-2)

Latest Dry Washing Techniques in Denim Garments (Part-2)
Asma Akhi
Md.Hasibur Rahman Sunny
Dept. of Textile Engineering
Bangladesh University of Business & Technology

Previous Part

Denim washing:
Denim washing is done to produce effects like color fading with or without patchiness, crinkles, seam puckering, hairiness, De-piling, softened-hand feel, stabilized dimensions etc.

Types of Denim Wash:
Denim washes are two types:

A. Mechanical washes
  1. Stone wash
  2. Micro-sanding
B. Chemical washes
  1. Denim bleaching
  2. Enzyme wash
  3. Acid wash 
Fig 02: Wash Type of Denim
Types of Garments Wash: 
  1. Normal wash/ garments wash/ rinse wash 
  2. Hand Brush/Hand Scraping
  3. Pigment wash 
  4. Whiskering
  5. Caustic wash 
  6. PP Spray/PP Sponge
  7. Silicon wash 
  8. Destroy
  9. Stone wash 
  10. Crinkle
  11. Enzyme wash 
  12. 3D
  13. Stone Enzyme wash 
  14. Tagging
  15. Acid wash 
  16. Sand Blasting
  17. Bleach wash
  18. Tinting wash Overall Whiskering
Dry Process:
Hand Scraping/Hand Brush:
  • Garments are wearing on a dummy or pattern board.
  • Hand scraping is done on specific area of garments by emery paper according to approve sample.
  • Different type of emery paper is used like 220, 320,400,600.
  • Most common used grade no of emery paper is 320.
  • Then sent for further processing.
  • This process is done manually by destroy machine.
  • Glass pencil/blade is used in this process.
  • Destroy is done on specific area of garments.
  • Destroying warp yarn by blade gives new outlook.
  • Garments sent for further processing.
  • Tagging is done on garments for fashion and value added fashion wear.
  • In this process tag pin is used.
  • At first garments are clipped with tag pin by tagging machine.
  • After wash upper portion of garment occurs crease marks & inside of tagging occurs dark shade.
  • At first design is produced on pattern board according to buyer requirement.
  • Then pattern board is placed inside the garments.
  • Then hand rubbing is done by emery paper on Specific area.
  • By using different types of emery paper (220,320,400,600) design is produced on surface of garments.
  • Most common used grade no emery paper is 320.
  • Then sent for further processing.
Potassium Permanganate (P.P) Spray:
  • At first a solution is made by potassium permanganate & water.
  • Sometimes CH3COOH (acetic acid) is used for solution preparation.
  • A spray gun machine is used for spraying the P.P solution.
  • Spray gun m/c spray the solution as per requirement.
  • A few minutes later reddish color is found on the surface of garments.
  • Then garments sent for further processing.
Permanent crinkle given on denim surface are known as crinkle effect. Resin application is done on denim to retain crinkle by using iron machine or pressing crinkle machine and even after wash.

First have to do spray resin on the specific area we want to create 3D effect. Without resin spray 3D effect is not possible. A garment is in metal plate. Crease is made in required place. Then two times pressing is done. The temperature is 1900c. Light temp is 1000 watt, it deep the resin and then it send to the curing to make wrinkle. Then it set to the dummy and makes 3D effect by the help of hand of workers manually.

Wet Process:

Desizing Wash:
  • This is very first & basic step but most important step of washing.
  • This process removes impurities, starch & stains during handling of fabric.
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 )
Enzyme wash:
To remove the size materials from the garments enzyme wash is applied. Enzyme wash is done on garments made from denim & jeans fabric, twill fabric garments. Sometimes knit items are also subjected for Enzyme wash. Garments made from indigo, vat, direct etc dyed fabric can be enzyme washed. Enzyme works chemically not mechanically for this reason it provide less damage/wastage then stone wash. It improves improve the color fastness & rubbing fastness. Enzyme improves the anti-pilling properties and decrease the hairiness hence it gives a very smooth surface of the garments.

Bleach wash:
Garments made from indigo, vat, reactive, direct etc dyed fabric can be bleach washed. It is a discoloration process by oxidation action. Color can be removed uniformly from the garment and removal of color done as per requirement. In general there are three categories such as light bleach (where maximum color is removed), medium bleach and bleach. All types of garment can be washed. Such as: woven knit garments. In case of woven fabric a pretreatment (Desizing) process is required. Dust, dirt, oil spot, impurities etc. are removed that may come from during process i.e. cut- ting, stitching and the back process.
  • Calcium hypo chlorite
  • Sodium hypo chlorite
  • Hydrogen peroxide
  • Potassium permanganate
Effect of Denim after Dry Process:

Hand Scraping/Hand Brush:
Scraping can be done on inflated rubber balloons for better effect (horizontal or vertical it’s up to operator’s convenience), even it can done plain wooden board of garment size & hand pressure should be uniform in order to get better results.

One of the most popular distressing effects currently, ‘Destruction’ is an art which make denim look unique & used.

This effect can be designed anywhere on the garment in different styles. Most favorite areas for tacking are on waistband, bottom hems, back pocket and front pocket corners etc. On front or back sides of garment, tacking can also designed horizontal of vertical patterns on full length panel.

Whiskers are one of the most important design of a used look garment. The idea of whiskers is taken from the worn out lines and impression patterns generated by natural wearing on hips and front thigh area.

Potassium Permanganate Spray:
PP Spray is being done on denim garments to achieve local abraded area to appear whiter than back ground indigo color shade.

Permanent wrinkles given on denim surface are known as crinkle effect. Resin application is done on denim to retain crinkle.

First have to do spray resin on the specific area we want to create 3D effect. Without resin spray 3D effect is not possible.

Function of Chemical Used in Washing:

  • It is used to remove mainly starches, waxes, fats, pectin’s, minerals & Indigo dye from denim, twills, poplin &canvass fabrics etc.
  • The action of enzyme during enzyme wash it hydrolysis the cellulose.
  • At first it attacks the having projecting fibers & hydrolyzed them.
  • Then it attacks the yarn portion & partly hydrolyzed them.
  • As a result color comes out from yarn portion & faded effect is produced.
Sodium Meta Bi-Sulphite (Na2S2O5):
  • It is used for neutralizing the activity of KMnO4 on fabric/solute.
Bleaching Powder (CaOCl2):
  • Bleaching agent is an oxidizing agent.
  • It is used for color out from denim garments.
  • We can achieve different shade (dark, medium, light) from garments by this agent.
Soda Ash (Na2CO3):
  • Soda ash create alkaline medium in wash bath.
  • It helps to uniform bleaching action in bleach bath.
  • It has cleaning power &help color fading affect of garments.
  • It is used for color fixing in dye bath.
  • It is also used for maintaining pH of wash bath.
Potassium Permanganate (KMnO4):
  • It is used for discolorations of fabric.
Softener (Cationic, nonionic):
  • It is used to make the garments soft.
  • It also provides excellent lubricating properties.
Sodium Chloride (NaCl):
  • It helps to exhaust dye in to the fiber.
Hydrogen Per Oxide (H2O₂):
  • H2O₂ creates the prime role in bleach wash technique.
  • In alkaline medium H2O2 breaks up and gives some perhydroxhyle ion.
  • Hydrogen per oxide is used in scouring, bleaching bath to occur bleaching action for white/ready for dyeing of gray fabric garments.
  • It is also used for neutralizing the garments from alkaline condition.
  • Resin is used for semi permanent creases in denim.
  • Binder is a film former consisting various polymer.
  • Polymer contains reactive group & it forms crosslink during curing.
Acetic Acid (CH3COOH):
  • To neutralize the alkaline condition of garment.
  • To control pH value in wash bath.
Next part will publish soon.....

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Mazharul Islam Kiron is a textile consultant and researcher on online business promotion. He is working with one European textile machinery company as a country agent. He is also a contributor of Wikipedia.

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