problems and remedies in wet processing of cotton 100% - p.shroff
DESCRIPTION
This presentation is based on problems & remedies in wet processing of cotton. starting from grey room to finishing.TRANSCRIPT
Problems & Remedies in Wet Processing of 100% Cotton (Woven)
- Pathik Shroff
PROCESS SEQUENCEGrey Room Shearing Cropping Singeing
Desizing
Scouring
Bleaching
Mercerization
Dyeing
Printing
Finishing
GREY ROOMSr .no. defects causes Remedies
01 Thick & thin place .
1.Immature fibre .2.Staple length.3.Neps.4.Drafting limitation
1.Selection of raw material.1a.Mature fibre.2.Good staple length.3.Maximum Neps should be removed (carding & combing).4.set Required draft.(no of doubling , speed of drafting roller.)
03 Weft bar Count variationDensity of pick more.
use Less variation of weft count.Required density of weft.
04 End & Pick missing
•Warp stop motion not working on loom at warp break.•Moving empty shuttle•Breakage of weft thread
•Use warp stop motion as per break .•New extra thread joining•Mending.
Weft barMissing Ends & Pick
SHEARING & CROPPING Sr .no. defects causes Remedies01 Cut or
holes damage to fabrics.
1.Presence of metallic particle on fabric.2.Due to abrading action.
1.Use magnetic metal detector in feeding device.1a.Removal of metal particle from grey fabric.2.Covering the emery roll with a piece of cloth which reduce abrading action.
02Rough & uneven surface of fabric.
Inefficient Sharpness of blade.
Grinding to blade & proper position & adjustment of blade
HOLES, CUT
SINGEINGSr .no. Defects Causes Remedies1 Incomplete
singeing1. low flame height2. fast fabric speed3. High Moisture content
1. flame height 4”- 6” 2. Fabric speed 90-120 m/min3. Ensure moisture content should be 6-8%
2 Uneven singeing [lengthways]
1. Change in fabric speed duringSingeing
1. Maintain Uniform fabric speed through outSingeing
3. Thermal damage orReduction in tear strength
1. Too slow fabric speed2. close distance between the fabric and the burner
1. Fabric speed must be set Above 60-70 m/min
2. From 6-8 mm upto 6-20 mm distance betweenthe fabric and the burner
FABRIC BEFORE SINGEING & AFTER SINGEING
DESIZINGSr. No. Defects Causes Remedies1. Incomplet
e desizing1. Inappropriate desizing bath pH
Set pH of bath depend on enzyme type of enzyme pH1. Malt extract 6-7.5 2. Pancreatic 6.5-7.53. Bacterial 5.5-7.5
2. Inappropriate desizing bath temperature
Temperature of bath must be 80-95◦ C .
3. Insufficient fabric pick-up
3. Use of wetting Agent
4. Deactivation of enzyme dueto presence of metals or othercontaminants
4a. Use of soft water4b. Use of appropriatesequestering agents
Sr. No. Defects Causes Remedies2 Uneven Desizing 1. Foaming in the bath 1. Use of appropriate
defoamers2. Inappropriate bathtemperature
2. Ensure bath temperature of bath 80-90◦ C
3. Non-uniform washing afterdesgizin
3. Ensure Hot wash at 95◦C for 10-15min Thorough and uniformwashing after desizing
4.Preferential drying of outerlayers of the batch
4a. Covering the batch withpolythene or other suitable sheet
4b. Keep the batch rolling
5.Temperature variationduring digestion
5. Covering the batch withpolythene or other suitable sheet
SCOURINGSr. No. Defects Causes Remedies1. Inadequate
absorbency orHigh residual impurities
Inadequate concentration ofscouring chemicals
Check recipeSodium carbonate - 2-3% owfAnionic detergent - 1-3 g/l
Incompatible or ineffectivesurfactant/wetting agent
Compatible and effectivesurfactant/wetting agent
Water hardness orineffective chelating agents
Use of soft water or effectivechelating agents
2 Tendering or damage orloss in strength
1. Presence of air in themachine, leading to theformation of oxycellulose
2. Contamination of iron
1a. Exclusion of air1b. Use of mild reducing agent2a. Water purification2b. Use of appropriatecomplexing agent
BLEACHINGSr. No. Defects Causes Remedies
1. Uneven whiteness 1. Use of inappropriatesurfactants2. Water hardness3. Irregular chemical feeding4. Condensation or water marks5. Foaming in the bath6. Inappropriate use ofdefoamer
1. Appropriate/ compatiblesurfactants2. Soft water or use ofsequestering agents3. Optimum chemical feeding4. Optimum steaming conditions5. Appropriate use of defoamer6. Appropriate use of defoamer
2 Resist marks 1. Deposits of insoluble salts ofsurfactants2. Redeposition of impurities
1. Use of soft water orappropriate chelating agents2a. Careful selection ofscouring auxiliaries2b. Thorough washing afterscouring
BLEACHINGSr. No. Defects Causes Remedies
3. Harsh handle 1. Silicate deposits 1a. Use of organic stabilisers1b. Optimum control of pH(low pH reduces silicatesolubility)1c. Thorough washing afterbleaching
4. Fibre degradation ORReduction in fibrestrength
1. Metal contaminants 1a. Treatment of water toremove metal contaminants1b. Use of appropriatecomplexing agents
Sr. No.
Defects Causes Remedies
5. Low degree of whiteness(Bleaching fabric by pad-Steam)
1.Residual sodium acetate afterNeutralization2.Too low bleaching pH3.. short steaming time4. low steamingtemperature
1.Thorough rinsing afterNeutralization
2. Ph 10-113. Steaming 60-90min4. Steaming at 90-95◦ CCheck no leakage of steam
MERCERIZATIONSr. No. Defects Causes Remedies
1. Low increase in lustre
1.Low concentration of Caustic2. Insufficient fabric stretchingwhile on the frame3. Dwell time
1.Caustic concentration must be 52◦ Tw or 26 Be2. Use of tensioner device3. dwell time should be 60 sec
2. Poor shrinkagecontrol
1. Insufficient fabric stretchingwhile on the frame2. Too much caustic on the fabricas it comes off the frame
1. Optimum fabric stretchingwhile on the frame2. Removal of excess causticfrom the fabric before it comesoff the frame
DYEINGSr. No.
Defects Causes Remedies
1. 1. Poor Washing Fastness in Direct Dyeing
1. Dye substantivity, too high
2. Inherent low fastnessproperties of the dyes
1a. Treatment with Copper salts Copper sulphate 0.5-2% owf, Acetic acid 0.5% temp- 80◦C time 30-45min
1b. Treatment with chromium compoundPotassium dichromate 2-3% owfAcetic acid 1-2% owf Temp- boil , time -30 min
2. Use of cationic dye fixing agents orother fastness improving aftertreatment
PROBLEMS IN REACTIVE Sr .no. defects causes Remedies
1.Shade change/inconsistent shade
Shade change/inconsistent shade
1. Residual peroxide, alkalinity or other contaminants in the substrate2. Water hardness3. Contamination of dyebath withcalcium, magnesium, chlorine orheavy metals4. Improper use of dyebathassistants, e.g. surfactants,sequestrants, fixatives, lubricatingagents
1. Substrate free fromcontamination before dyeing2. Use of soft water or appropriatesequestrants3. Use of appropriate sequestrants4. Use of compatible dyebathassistants
2. Poor colour yield Poor colour yield 1. Poor pre-treatment2. Residual peroxide in thesubstrate3. Dye hydrolysis (only in caseof reactive dyes)
1. Good pre-treatment2. No residual peroxide in thesubstrate3a. Careful storage of dyes3b. Use of freshly prepared dyesolution
PROBLEM IN VAT DYEINGdefects causes Remedies
Poor levelling/unevendyeing
1. Low dye diffusion2. High dye affinity3. Dyes of poor migration4. Over reduction of the dye
.5 Low liquor flow rate6. Poor rinsing beforeoxidation7. Uneven washing/soapingafter-treatments.
1. Use of dyes of good diffusion2. Use of dyes of optimumaffinity3. Use of dyes of goodmigration4. Use of sodium nitrite to avoid over reduction of the dye
5. Optimum liquor flow rate6. Thorough rinsing beforeoxidation7. Thorough and uniformwashing/soaping after treatments.
Premature oxidation 1. Presence of air inside theMachine.2. Insufficient amount of sodiumdithionite and/or alkali
1. Prevention of air inside theMachine.2. Optimum amount of sodiumdithionite and/or alkali
cause reason remedie
Oxidation patch in vat dyeing
Improper oxidation - Sodium bicarbonate rinsing after after dyeing & prior to oxidation
Poor rubbing fastness 1. Dyes of poor rubbing fastness2. Catalytic damage of thematerial3. Presence of polyvalent ions4. Too high moisture in the testmaterial5. Improper use of finishing agent
1. Use dyes of good rubbingfastness2. No catalytic damage of thematerial3. Use of appropriate complexingagents4. Proper conditioning of the testmaterial5. Proper use of finishing agents
Problem Cause remedie
Shade change/inconsistent shade
1. Residual peroxide, alkalinityor other contaminants in thesubstrate2. Water hardness3. Contamination of dyebath with calcium, magnesium, chlorine or heavy metals4. Improper use of dyebath assistants, e.g. surfactants,sequestrants, fixatives, lubricating agents
1. Substrate free fromcontamination before dyeing2. Use of soft water orappropriate sequestrants3. Use of appropriatesequestrants4. Use of compatible dyebath assistants
Other Dyeing Problem
Problem Cause remedieSpecky dyeing. Too much foaming during
padding.
water drop on fabric before or after padding.
Add defoamer if required depending on class of dyestuff.
take preventive measures.
maintain the temp. speed & time .
Patchy dyeing. Insufficient dip in padding trough
Selection of proper padding mangle.
Centre to selvedge variation. Uneven wearing out of rolls of padding mangle.
Temp.gradient from centre to side of steaming chamber
Check the uniform expression of padding mangle.
Ensure uniform temp.across width of steamer.
Tailing effect. Too large size of padding trough. Use narrow & deep trough of smaller capacity.
Patchy DyeingShade Variation Shade Bar
Problem in Jigger Dyeing
defects causes Remedies
Dark or light selvedge . Non-uniform batching on jigger .
Proper batching on jigger.
Streakiness. Improper function of tensioning device in jigger lead to too high tension to wet state.
Ensure proper functioning of tension rollers on jigger.
Face to face variation. Too high batching tension on jigger.
Ensure correct batching on jigger.
Problems in Jet & Winch DyeingSr .no.
defects causes Remedies
01Crow –feet mark (crush mark).
Improper jet diameter . Use suitable jet depending on fabric quality.
02 Oil stains . Use wrong type defoamer which are break in rapid jet dyeing cause staining problem.
Use self emulsifying type silicone defoamer.
Crush marks Oil Stains
Problems in Continuous Dyeingdefects Causes Remedies
Specky dyeing. Too much foaming during padding.
water drop on fabric before or after padding.
Add defoamer if required depending on class of dyestuff.
take preventive measures.
maintain the temp. speed & time .
Choke feeding lines. Inferior dye dispersion Improper selection of dyestuff.
Centre to selvedge variation. Uneven wearing out of rolls of padding mangle.
Check the uniform expression of padding mangle.
Tailing effect. Too large size of padding trough. Use narrow & deep trough of smaller capacity.
Use hydraulic controlled rollers Colour dosing system PLC
Dye stuff stain Due to improper handeling improper mixing of dyes
•Ensure proper housekeepingProper mixing of dyes
Dye Stain White Spots
PRINTING
Defect cause by Hanging Thread
Problem Cause remedies
A break in Pattern of Printed fabric caused by Hanging Thread
Loose thread not treammed well before Printing
Non mendable
MISPRINT
Problem Main Cause Remedies:
MISPRINT
-Design not set properly
-unequal pressure
-Screen Design not Properly Engraved
-cloth feed with uneven tension
-Check Proper Feeding of cloth & Speed of m/c
-Ensure proper engraving of Design
TINTING
Problem Cause Remedies
Tinting
-Uneven Printing roller & doctor blade pressure
-Printing Paste level not maintained
-- defective doctor blade
- Printing table not proper
-Check viscosity of Printing Paste
-Check doctor blade
-Check Screen
BLURERD PATCH
-
Problem Cause Remedies
Blurred patch Uncleaned Doctor blade & printing roller
-Doctor blade not properly aligned
cleaned Doctor blade & printing roller
-Doctor blade properly aligned
WATER MARK
Problem Cause remedies
Water maks-Contamination with water prior to tinting on padding mangle-Surface pressure of one layer over another
-Ensure proper cleaning of padding mangle-- ensure optimum pressure
MISFITS
Problem cause Remedies
Misfits
-Printing screen Not adjusted properly-Improper feed of fabric-Faulty engraving
-Proper adjustment of screen-- ensure proper feed of fabric use guiders, feed rollers-Ensure proper Engraving acc. To pattern
FLUSHING
Problem Cause remedies
Flushing
-Printed area bleed into unprinted Portion-Removal of unfixed print
Do curing at reqired temperature
SPOTTING
Problem Cause remedies
Spotting-Unclean Screen roller
-Spots due to handling
-Poor uptake of print paste
-Cleaning of screen
-Avoid marks in steaming
-- ensure proper squeegee pressure
PRINT COLOUR VARIATION
Problem Cause Remedies
Colour variation
-Uneven squeegee pressure
- Check even appliation of pressure through out application of print paste.
BLEEDING
Problem Cause Remedies
Bleeding-Too low viscosity of color paste-Too high dyestuff concentration
Ensure proper viscosity of Print paste - Ensure optimum concentration of dyestuff taken
STAINING DURING STEAMINGProblem Main cause Remedy:
Staining during steaming
-Poorly washed printing Table
-Irregular Steam & temperature
Ensure Optimum Temperature while Steaming for reactive 102-105ºC
SLIGHT TOUCHING
Problem Main Cause Remedies
SLIGHT TOUCHING -Uneven Squeegee Pressure
-A squeegee with improper Hardness
-Improper viscosity of paste
-Improper use of thickener
-Optimum squeegee pressure
-- check squeegee before use
-Ensure viscosity of paste
-Proper use of thickner
DOUBLE PRINTING
Problem Main Cause Remedy
Double printing
-Disfigured design-Poor engraving-Poor cloth adhesion
Ensure Proper engraving
PRESSING PASTE BY FRAMEProblem Cause Remedies
Pressing paste-Poor belt drive and frame installation
-Frame mark in printed area
-Proper frame installation over fabric
FINISHING
STARTING MARKSProblem Cause Remedies
Staring marks 1. Sudden start, stopped of machine
2. Squeezing roll not properly clean
3. At start fabric pass throgh finishing chemical & not squeeze properly
1. Avoid sudden start and stoppage
2.Squeezig roller clean 3. Ensure proper squeezing
action
BOWINGProblem Cause Remedies
Bowing 1. Uneven tension during processing
2. Guiders not present
1. Maintain even tension
Use of Weft straightner
2. Use of guiders
PILLINGProblem Cause Remedies
Pilling
1. Broken filament
2. Low twist
1. Shearing , singeing
2. Ensure optimum twit
PIN HOLESProblem Cause Remedies
Pin holes 1. Stenter pin 1. Go for clip
for holding fabric
Finishing (Stenter)Sr .no. defects Causes Remedies
01 Clips cuts and escape .
Inadequate grey width or reed space
Mechanical defect in clip bar & chain rails of the stenter.
Use provide adequate grey width & reed space with shrinkage expected.
Ensure proper maintenance of clips & chain rails of stenter.
02Yellow stains . Overheating & curing of the
finished especially when acid liberating are used in finish .
Optimum drying & curing condtion w.r.t time ,temp.
03Oil dropping & carbon soot .
Condensation of duct & water , oil particles
Ensure proper cleaning of stenter exhaust.
04 Uneven heat setting.
Variation in parameter Maintain parameter.
Calendering (Finishing)
Sr .no.
defects causes Remedies
01 creases & cut . non-alignment of guide rolls on calendering m/c giving rise to crease formation.Improper stitching of cloth.
Proper selvedge to selvedge stitching of material & proper feeding over well aligned guide rolls .
02 Dent mark & stains .
Dents in the calendering bow
Filling of dent.& proper brushing of the bowl .
Sanforiser (Finishing)
Sr .no. defects causes Remedies
01 Rubber blanket marks .
Dent or uneven surface of the rubber blanket .
Ensure proper and even grinding of rubber blanket .
REFRENCES• Towards zero Defect Amubhai patel
• www.textilelerner.com
• Major fabric defects during chemical processing • Quality and Process control S.M. Doshi & HA Shah • Chemical technology of fibrous materials - F. Sadov
• Technology of Dyeing – V. A. Shenai
• www.kyungin.co.kr/eng/sup/page1.htm#list1
• www.textileinfo.com
• www.alleycatscratch.com
• Critical Solutions In The Dyeing Of Cotton Textile Materials R. Shamey and T. Hussein
• Reduction of values in textile industry,(Bombay textile research ass.nov.14 1983) p-23-38.
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