Introduction


Jig dyeing is very common for woven fabrics due to the crease-free process. Many problems are associated with it, most commonly tailing problem (shade variation along the length of the fabric). In this paper, a practical approach has been presented for dyers to cope the tailing problem. Sometimes listing (shade variation from side-to-side i.e. centre to right/left of width of the fabric) is also a problem. A suitable dye dosing criteria is suggested to jig dyers that present a fault-free jig dyeing of woven fabrics.


Equipment


We have taken following jig machine for our observation. The specifications can vary from machine to machine, but the main theme is to solve the tailing and listing problems of jig dyeing machine. The technical specifications are given below:


Jigger Dyeing Machine Specifications


  • Roller Width = 122"

  • Centre Distance = 21"

  • Fabric Capacity = 1000-3000 meters

  • Main Roll Dia = 8.3"

  • Temperature = 135 oC

  • One side door, Pressure gauge 130 lbs (8.9 Bar), Temperature sensor, temperature automatic control

Symptoms, Diagnosis and cure concept in Jig dyeing



SYMPTOMS

DIAGNOSIS

CURE

Listing

1.      High speed & speed variation (150 m/min i.e. 20 mints per cycle)

2.      Temperature variation side to side

3.      Dosing criteria


1.      Constant speed & Medium speed (80-100 m/min i.e. 30-35 mints per cycle)

2.      Control of temperature & proper winding of fabric through jig main rollers

3.      Follow the Dosing Criteria heading (given in below)


Tailing

1.      High Dyes / Chemicals Concentration

2.      Unknown disperse/reactive dyes properties profile

3.      Different migration of different disperse and reactive dyes

4.      pH Variation

5.      Liquor level variation

6.      Levelling issues

7.      Temperature (8-10 oC) variation during running of lot

8.      High speed & speed variation (150 m/min i.e. 20 mints per cycle)

9.      Extra length of fabric meters (more than the specified capacity of jig machine)


1.      Dyes Dosing should be dosed in portions (400 to 400 meters fabrics )

2.      Need to use Medium sublimation disperse dyes & medium substantive reactive dyes

3.      Balance migration properties in trichromatic shades

4.      Use of acidic buffer

5.      Liquor level can be controlled by variable dosing

6.      Use of dispersing / levelling agents

7.      Speed should be lower (increment in dwell time)

8.      Increase the dwell time (35-40 min per cycle) with constant lower speed

9.      Shorten the length of fabric i.e. 20%


 

Dyeing Dwell Time

Dwell time is fabric-liquor contact time. For example, if it takes 5 hours to jigger-dye 1,000 meters of fabric, it means it takes only 18 seconds to dye one meter of the fabric. The diffusion process of a dye depends on time; more contact time with dye liquor will give full depth shades. The speed of the fabric (metres/minute), tension of jig main rollers and temperature of dye liquor should be consistent throughout the process to get even and uniform shade.


Jigger Data:


Details

Normal Dyeing

Suggested Dyeing

 

Fabric Meters

3000

2500

 

Total Dyeing Cycles

06 (2 Cold & 4 hot)

06 (2 Cold & 4 hot)

 

Speed (m/min)

135

75-80

 

Avg. Cycle Time (mints)

22

35

 

Total Time (mints)

6*22 = 132

6*35 = 210

 

Dyeing time/meter (sec)


132/3000 = 0.044*60 = 2.7

210/2500 = 0.08*60 = 5.1

 

 


Shade Variation

As it is an inherent problem with jig dyeing machine, it gives shade differences i.e. tailing and listing, if dye dosing and circulation of fabric through dye liquor are not controlled properly. There are some major reasons of shade variation, some of them are:

  • Temperature variation with width of the fabric or length of the fabric

  • Improper dye dosing

  • Uneven tension on fabric when end/cycle changes

  • Inconsistent speed of the fabric

Therefore, it is advisable to use closed jigger machine for consistent temperature throughout the dyeing process and standardized dye doing system.

1.     Dosing Criteria

NORMAL DOSING

SUGGESTED DOSING

     • 1st end 1/2 dosing

     • 2nd end 1/2 dosing

     • 1st end 1/6 dosing

     • 2nd end 1/6 dosing

     • 3rd end 1/6 dosing

     • 4th end 1/6 dosing

     • 5th end 1/6 dosing

     • 6th end 1/6 dosing

 

 



DYEING METHOD: ONE-BATH TWO STEPS DISPERSE DYEING


1st Cycle

2nd Cycle

1.     Fill the jigger bath 200 litres (or 50% of the total water level of machine) with water and add half quantity of buffer.

2.     Make stock solution of 200 litres in four drums or any suitable item with adding of disperse dyes.

3.     Add 17 litres solution from the stock solution in the bath and run the 400 meters fabric.

4.     Similarly repeat this procedure until the end of one cycle, so there will be six doses in single cycle after each 400 meters


1.     For 2nd cycle add another half quantity of buffer & repeat the same procedure as done in 1st cycle with remaining 100 litres stock solution.

2.     After completion of dosing and two cycles, now for initiating the 3rd cycle, first maintain the temperature up to 90 oC and then raise the temperature up to 130 oC Check the pH with suggested time & temperature.

3.     Run 4th cycle @ 130 oC , 35

4.     Repeat reaming cycles same as given above




REACTIVE DYEING


1st Cycle

2nd Cycle

1.     Fill the jigger bath 200 litres with water and add half quantity of salt

2.     Make stock solution of 200 litres in four drums with adding of reactive dyes

3.     Add 17 litres solution in the bath and run the 400 meters fabric

4.     Similarly, repeat this procedure until the end of one cycle, there will be six doses in each cycle after each 400 meters


1.     For 2nd cycle add another half quantity of salt & repeat the same procedure as done in 1st cycle with remaining 100 litres stock solution

2.     After completion of dosing and two cycles, now for initiation of 3rd cycle, first maintain the temperature up to 60 oC and then add soda ash via checking the pH (9-11)

3.     Run 4th cycle at the rate of 60 oC 35

4.     Repeat reaming cycles same as given above



References:

1.      Duckworth, C. (Ed.). (1983). Engineering in textile coloration. Dyers Company Publications Trust.

2.      Shamey, R., & Hussein, T. (2005). Critical solutions in the dyeing of cotton textile materials. Textile progress, 37(1-2), 1-84.

3.      Shore, J. (1995). Cellulosics dyeing. Society of Dyers and Colourists.


About the Author:

Muhammad Awais Imran and Muhammad Moosa Abdul Rehman are visiting faculty members of Department of Textile Science, Faculty of Engineering, Science & Technology, Indus University, Karachi, Pakistan.