“Dyeing Faults”

Abstract

Wet processing methods are included with dyeing, printing and finishing process. A grey end product is not desired to anyone who likes to use an attractive and comfortable product, for this reasons raw materials are treated in different stage of manufacturing to make it suitable. If we want so we should treated that’s raw materials by wet processing method. Dyeing is the first step of wet processing method. Dyeing is also called coloration process & an important process. In this paper we discussed about the faults that are related to dyeing and their remedies.

Key words

Dyeing, Dyeing faults, Fiber dyeing faults, Yarn dyeing faults, Fabric dyeing faults.

Introduction

Dyeing is a distribution process in which the dye or pigment is distributed at least two phase’s system i.e. the dye/pigment bath or solution and the substrate (textile material). In this process dyeing is done in a dye bath. Dye bath contain a solution of dyes, chemicals & auxiliaries. Dyes or pigments are the main coloring substance in the dyeing process. There are various types of dyes and pigments which are used for coloring textile materials.

Dyeing is generally done for fiber, yarn and fabric. Textile materials could be natural or man-made. Depending on the types of the textile material dyes, chemicals and dyeing process varies. During the dyeing of textile material a bonding is made between the fiber and textile materials or dye molecules are trapped within the molecular structure of the textile material. Performance of a textile material depends on dyeing performance. Several faults are occurred during dyeing & if we want a dyed textile material without faults we need to give deep concern on dyeing process.

Dyeing faults

Dyeing is a process of coloring fibers, yarns, or fabrics with either natural or synthetic dyes. Many known-unknown faults occur during dyeing operation Such as many faults appears during fiber dyeing, yarn dyeing & fabric dyeing. Reasons & Remedies of dyeing faults are given below:

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Fiber Dyeing faults

In fiber dyeing no severe problems/faults occurred only Uneven dyeing is occurred. The reasons/causes & remedies of uneven fiber dyeing are given below:

Reasons:

Uneven pre-treatment( Scouring & Bleaching). Due to excess loading. Due to improper flow rate. Due to rushing of fibers in the inlet of the fibers.

Figure: Uneven fiber dyeing.

Remedies:

Proper pretreatment. Material loading according to the machine capacity. Pump capacity should be high & time to time cleaning required. Ensure proper blocking the fibers after loading & the carrier bag should made from high

strength material.

Yarn Dyeing faults

In dyeing process different faults can be occurred for various factors. Among all the dyeing process package yarn dyeing is different. In package yarn dyeing different types of faults are occurs but followings are the most common:

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Color variation from the inside to the outside of the yarn package

Color variation from the inside to the outside of the yarn package means the variation of shade in different layers of a yarn package. A textile engineer must have knowledge about the shade of color because a small percentage of shade variation can move a textile material to rejection. Reasons/causes & Remedies of uneven yarn dyeing are given below:

Reasons:

Uneven pre-treatment( Scouring & Bleaching). Improper color dosing. Uneven heat setting in case of synthetic yarn. Lack of control on dyeing machine.

No uniformity of package.

Figure: Unlevel yarn dyeing.

Remedies:

By ensuring proper pretreatment. By ensuring even heat setting in case of synthetic yarn. Proper dosing of dyes & chemicals. By ensuring uniformity of package

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Damaged yarn

During yarn package dyeing yarn may be damaged due to high pressure & faulty processing. Reasons/causes & Remedies of damaged yarn during dyeing are given below:

Reasons:

Pump pressure too high Poorly wound package Manual handling errors Excessive processing

Remedies:

By ensuring standard pump pressure. By controlling manual errors. By ensuring properly wound package with standard tension.

Package to Package Shade variation

Package to Package shade variation means the appearance of different shade of same color in different package while dyeing in the same machine at the same time. Reasons/causes & Remedies of Package to Package Shade variation are given below:

Reasons:

Improper setting of yarn packages in the machine. Lot mixing of the package. Count variation of package.

Remedies:

By ensuring proper setting of yarn packages in the machine. By ensuring no lot mixing of the packages. By ensuring same count of the packages.

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Color Spot

Color spot means presence of spots different color on the yarn package. Reasons/causes & Remedies of color spot are given below:

Reasons:

Floating of dye particles in the air. Improper per-oxide killing. Improper mixing of dyestuffs

Figure: Color spot on yarn package

Remedies:

By ensuring proper per-oxide killing. By ensuring mixing of dyestuff. Make sure that no dye molecules are floating in the air.

Lighter areas of yarn

Reasons:

Air trapped in the package.

Remedies:

Complete air removal has to be ensured prior to pressure build up for uniform results. Optimum values of pH, Temp. & Time parameters have to be maintained during every

stage of processing. 

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Fabric dyeing faults

Fabric dyeing faults may appeared after dyeing of both knitted & woven fabric, And the faults occurred after dyeing are mostly similar both in woven& knit fabric. Common fabric dyeing faults their reasons & remedies are given below:

Uneven Dyeing

Reasons: 

Uneven pretreatment (uneven scouring & bleaching). Improper color dosing. Using dyes of high fixation property. Uneven heat-setting in case of synthetic fibers. Lack of control on dyeing m/c

Figure: Uneven fabric dyeing

Remedies: 

By ensuring even pretreatment. By ensuring even heat-setting in case of synthetic fibers. Proper dosing of dyes and chemicals. Proper controlling of dyeing m/c

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Batch to Batch Shade Variation 

Reasons: 

Fluctuation of Temperature. Improper dosing time of dyes & chemicals. Batch to batch weight variation of dyes and chemicals. Dyes lot variation. Improper reel speed, pump speed, liquor ratio. Improper pretreatment.

Figure: Batch to Batch shade variation

Remedies: 

Use standard dyes and chemicals. Maintain the same liquor ratio. Follow the standard pretreatment procedure. Maintain the same dyeing cycle. Identical dyeing procedure should be followed for the same depth of the Shade. Make sure that the operators add the right bulk chemicals at the same time and

temperature in the process. The pH, hardness and sodium carbonate content of supply water should check daily.

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Patchy Dyeing Effect

Reasons: 

Entanglement of fabric. Faulty injection of alkali. Improper addition of color. Due to hardness of water. Due to improper salt addition. Dye migration during intermediate dyeing. Uneven heat in the machine, etc.

Figure: Patchy Dyeing effect

Remedies: 

By ensuring proper pretreatment. Proper dosing of dyes and chemicals. Heat should be same throughout the dye liquor. Proper salt addition.

Roll to Roll Variation or Meter to Meter Variation

Reasons: 

Poor migration property of dyes. Improper dyes solubility. Hardness of water. Faulty m/c speed, etc

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Figure: Roll to Roll Variation

Remedies: 

Use standard dyes and chemicals. Proper m/c speed. Use of soft water.

Crease Mark

Reasons: 

Poor opening of the fabric rope. Shock cooling of synthetic material. If pump pressure & reel speed is not equal. Due to high speed m/c running.

Figure: Crease Mark

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Remedies:  

Maintaining proper reel sped & pump speed. Lower rate rising and cooling the temperature. Reducing the m/c load. Higher liquor ratio

Dye Spot

Reasons: 

Improper Dissolving of dye particle in bath. Improper Dissolving of caustic soda particle in bath.

Figure: Dye spot

Remedies: 

By proper dissolving of dyes & chemicals. By passing the dissolved dyestuff through a fine stainless steel mesh strainer, so that the

large un-dissolved particles are removed.

Wrinkle Mark

Reasons: 

Poor opening of the fabric rope. Shock cooling of synthetic material. High temperature entanglement of the fabric.

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Remedies: 

Maintaining proper reel sped & pump speed. Lower rate rising and cooling the temperature Higher liquor ratio

Softener Mark

Reasons: 

Improper mixing of the Softener. Improper running time of the fabric during application of softener. Entanglement of the fabric during application of softener

Figure: Softener markRemedies: 

Maintaining proper reel sped & pump speed. Proper Mixing of the softener before addition. Prevent the entanglement of the fabric during application of softener

Fabric Hole

Reasons:

Excessive amount of acid in the dye bath. Excessive temperature.

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Figure: Fabric hole

Remedies:

Proper dosing of acid in the machine. Standard temperature should be maintained.

Conclusion

Many faults that appear in fabrics and yarns after dyeing are not all related to dyeing. Many of these faults can be traced back to prior production processes. It is important therefore when assessing a fault to try to ascertain the root cause. Careful consideration of the possible cause of the fault will enable suitable corrective action to be taken to ensure that the same faults do not re-occur.

Reference

http://textilefashionstudy.com/

http://www.ifc.net.au/

http://www.fibre2fashion.com/

http://en.wikipedia.org/

http://textilelearner.blogspot.com/

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