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98738826 denim
This document summarizes the denim processing steps including desizing, abrasion, bleaching, and finishing. It defines key terms like denim fabric composition and dyeing methods. The processing involves both dry techniques like sandblasting and wet processes like enzyme washes using amylase, cellulase and other chemicals to break down starch, weaken fibers, and decolorize indigo for stonewashed effects. Proper chemicals, temperatures, pH and times are outlined for each wet processing step.
98738826 denim
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- 2. DEFINITIONS • DENIM :A Firm 2/1 or 3/1 cotton twill-weave fabric with dyed blue warp and raw white weft. ( similar to yarn dyed fabric ) • Warp is dyed with indigo dyes . • Various dyeing methods, recipes, concentrations, the reactions and oxidation time influences the effect and characteristics of the finishes
- 3. Basic Process line Stone washed Desized Fabric is converted into garments Sized Indigo-dye warp and raw white weft Woven in a 2/1 or 3/1 twill weave
- 4. Garment process DENIM PROCSSING DRY PROCESS WET PROCESS Scraping Sand blasting KMnO4 Spray Acid wash
- 5. Dry process • Sandblasting : to produce localized abrasion • Scraping : manual scraping using sand paper or grinding machine as per design • KMnO4 Spraying : an alternative blasting technique • Acid wash : use of thremocol ball and bleach in a single belly machine
- 6. Denim Wet processing •Desizing : a process intended to remove size finish constituents from fabric before enzyme wash or bleaching • Abrasion : a process which facilitates the indigo dye to be removed from the surface of the cotton fibre . • Bleaching : a process intended to decolorize indigo by using bleach liquor (NaOCl) • Softener wash : to improve the hand feel of the garment by cationic or silicone softener
- 7. Chemicals and theiruses • Non ionic wetting agent : to increase the absorbency of the garments • Lubricating agent : to avoid streak formation • Amylase : an enzyme used to break down insoluble starch to soluble glucose ( 90 % of sizing material contains insoluble starch ) • Pumice stone : used during denim washing to get the grain effect ( replaced by enzyme to large extent )
- 8. Continued … • Anti back staining agent : to avoid re deposition of the indigo dyes on the fabric surface • Cellulase : an enzyme used to weaken the cotton fiber and hence increase abrasion • NaOCl : Sodium hypochlorite used to lighten the shade of indigo • Laccase : enzyme used to decolorize indigo ( by converting indigo into colorless compound called Isatin ) • Softeners : to improve hand feel and protect the denim from Ozone
- 9. Benefits of usingenzymes • Maximized fabric strength retention • Stone free processing • Fast processing • Improved wash look • No or less Garment damage • No machine damage • Easy handling and cost effective
- 10. Desizing • MRL : 1: 5 to 1 : 10 • pH : 5 to 6.5 • Temp : 60 Deg C • Time : 20 min • Chemicals ad dosage : • non ionic wetting agent ( 1 gpl ) • Lubricating agent ( 0.5 gpl ) • Anti back staining agent ( 0.5 to 1 gpl ) • Amylase ( 0.5 to 1 gpl ) ( enzyme for breaking down starch into soluble glucose )
- 11. Abrasion • MRL : 1: 5 to 1 : 10 • pH : 6.5 • Temp : 55 Deg C • Time : 20 to 45 min • Chemicals : • Anti back staining agent ( 0.5 gpl to 1 gpl ) • Cellulase( 0.5 to 1 gpl )( enzyme for weakening cotton fiber by converting the cellulase into glucose )
- 12. Bleaching • MRL : 1: 5 to 1 : 10 • pH : neutral • Temp : Room Temp • Time : depends on the shade • Chemicals : • NaOCl
- 13. Bio bleach • MLR :1:5 to 1:10 • pH : 4 to 5.5 • Temp : 60 to 70 Deg C • Time :15 to 20 min • Chemical used : – Laccase :1 gpl to 2 gpl
- 14. Special finishes • Pigment spray • Direct and reactive dye tinting • Transfer printing • Rubber feel • Indigo retention • Permanent crease • Raw ( or undesized ) look