Declaration of the Candidate and Supervisor 
I A.L .K Amarasekara, hereby certify that the work described in this dissertation was 
carried out by me in the Department of Textile and Clothing Technology, University 
of Moratuwa and Hayleys mgt Knitting M i l l pic .This dissertation is the result of my 
own work and does not incorporate without acknowledgement any material 
previously submitted for any university or institution for any other academic 
qualification. 
Also I hereby grant to University of Moratuwa the non-exclusive right to reproduce 
and distribute my dissertation in whole or in part in print, electronic or other 
medium. I retain the right to use this content in whole or part in future works. 
The above candidate has carried out the research for the Master degree under my 
supervision. 
Date: 
Date: <5 - / - 2 - ^ 
Improving Colour Reproducibility in Bulk Production of Single 
Jersey Cotton knits using Reactive Dyeing 
LIBRARY 
UNIVERSITY OF MORATLWA, SRI LANKA 
UORATUIr/A 
Athapaththu Hewawasam Liyanage Kumarasiri Amarasekara 
(8/8704) 
Dissertation submitted in partial fulfillment of the requirements for the degree of Master of 
Science 
University of Moratuwa 
lllllllllllllll 
104514 
Department of Textile and Clothing Technology 
University of Moratuwa 
Sri Lanka 
en^i 5(04-3) 
March 2012 
104514 
Declaration of the Candidate and Supervisor 
I A.L .K Amarasekara, hereby certify that the work described in this dissertation was 
carried out by me in the Department of Textile and Clothing Technology, University 
of Moratuwa and Hayleys mgt Knitting M i l l pic .This dissertation is the result of my 
own work and does not incorporate without acknowledgement any material 
previously submitted for any university or institution for any other academic 
qualification. 
Also I hereby grant to University of Moratuwa the non-exclusive right to reproduce 
and distribute my dissertation in whole or in part in print, electronic or other 
medium. I retain the right to use this content in whole or part in future works. 
The above candidate has carried out the research for the Master degree imder my 
supervision. 
Date: c>'i--^7'fi~ 
Date: O^-^^^^ ^ 
Abstract 
Dyeing is a widely used operation in textile processing, and dyed textiles account for 
significant amount of the total textile production. Colour, particularly colour consistency, is 
a critical quality parameter in dyed textiles, on which is a high level of expectation is placed 
by apparel manufacturer, as it can lead to the mismatching of garment panels and non-
conformity with customer requirements in readymade garments. Reactive dyes are popularly 
applied to cotton knits due to the advantages of reactive dyes such as higher level of colour 
fastness properties, obtaining different shades, and the applicability of various methods. 
However, a lack of reproducibility in some cases has been observed in reactive dyeing on 
cotton knits. Hence reproducibility has to be enhanced in order to obtain a cost effective, 
competitive and environmental friendly reactive dyeing process. Therefore this research 
focuses on the improvement of reproducibility of reactive dyeing on cotton knits. 
I The reactive dyeing process depends on certain important factors such as the level of 
pretreatment, quality of dyes, dyeing auxiliaries and water used, and the dye bath variables. 
Therefore the bulk dyeing trials are performed on the level of pretreatment and the other 
^ factors are kept constant. Thus the number of bulk dyeing trials including light, medium and 
dark shades, are conducted on variables such as degree of whiteness, pH level and 
absorbency of the material which are achieved during the pretreatment process. The 
recommended degree of whiteness for this reproducibility was not exactly determined 
because it ultimately affected to the strength of the white material. Therefore it can be 
concluded that the degree of whiteness should be kept as high as possible without damaging 
the fabric. The recommended pH level for the improvement of reproducibility was pH = 7. 
At this pH level, maximum level of reproducibility can be achieved. The recommended 
absorbency level for the improvement of reproducibility was 3 sec. according to the test 
method of American Association of Textile Chemists and Colorists (AATCC) 79.By 
maintaining the above parameters within the recommended range acceptable level of 
reproducibility can be achieved in dyed cotton knits. 
ii 
Dedication 
/ lovingly dedicate this dissertation to my wife, 
who supported me 
each step of the way 
iii 
Acknowledgement 
I would like to take this opportunity to express my sincere thanks and gratitude to my 
research Supervisor Dr.(Mrs.) Samudrika Wijayapala, Senior Lecturer, Department 
of Textile and Clothing Technology of the University of Moratuwa. 
My heartfelt thanks to Mr V.A.Nandasena former Managing Director Vantex (Pvt) 
Ltd for providing me with guidance and encouragement. 
It is with sincere thanks that I would recall the helping hands offered by Head of 
Department Dr Gamini LanaroUe and all the staff members of the Department of 
Textile and Clothing Technology of the University of Moratuwa to complete this 
research study successfully. .^ 
I would like to thank Mr. S.N.Niles, Senior Lecturer, Department of Textile and 
Clothing Technology of the University of Moratuwa. 
I extend my sincere thanks to Mr. CP. Malalanayake and Ms. Dilum Dissanayaka, 
staff technical officers Department of Textile and Clothing Technology of the 
University of Moratuwa for supporting me in laboratory work. 
iv 
Table of Contents 
Page No 
Declaration of the candidate & Supervisor i 
Abstract i i 
Dedication - i i i 
Acknowledgement iv 
Table of content v 
List of figures ix 
List of table x 
List of abbreviations ' x i 
1. Introduction 1 
1.1 Scope of Study 1 
1.2 Statement of the Problem 2 
1.3 Objectives of the Study 3 
1.4 Significance of the Study i 3 
1.5 Problem Identification 4 
2. Literature Survey 5 
2.1 Reactive dyes for cotton knits 5 
2.2 Properties of sumifix supra dyes 7 
2.2.1 Effect of Metalic ions in water 9 
2.2.2 Compatibility of Combination dyeing 9 
2.3 Dyeing mechanism of sumifix supra dyes 10 
2.4 Contributing factors for reproducibility in bulk dyeing . 11 
2.4.1 Preparation of cotton material to be dyed 12 
2.4.2 Weight of the material to be dyed 12 
2.4.3 WeigMng of dyes/dyeing auxiliaries 12 
2.4.4 Dye bath variables 12 
2.4.5 Time and temperature profile 12 
2.4.6 Machine flow and sequence 12 
2.4.7 Combination of dyes 12 
V 
2.5 Theoretical solutions for RFT dyeing 13 
2.5.1 Study 1 13 
2.5.2 Study 2 13 
2.5.3 Study 3 • 14 
3. Experimental Procedure • 16 
3.1 Material used for experiments 16 
3.2 Dyes used for experiments 16 
3.2.1 Chemical used for experiments 16 
3.3 Preparation of samples for dyeing 17 
3.3.1 Scouring of cotton 17 
3.3.2 Bleaching of cotton " 17 
3.4 Dyeing machine used and evaluation of reactive dyeing 
reproducibility 18 
3.4.1 Spectrophotometer used for evaluation of reactive dyeing 
reproducibility 19 
3.4.2 Selecting of pass/fail criteria 20 
3.5 Experimental method 21 
3.5.1 Selections of variable and fixed factors 21 
3.5.1.IVariable factors 21 
3.5.1.2 Fixed factors 21 
3.5.2 Selection of shades for the experiment v 21 
3.5.3 Light sources used for measuring AE 22 
3.5.4 Experimental design 22 
3.5.4.1 Experiment on the effect of degree of whiteness 22 
3.5.4.2 Experiment on the effect of pH value 26 
3.5.4.3 Experiment on the effect of level of absorbency 30 
4. Results and discussion 34 
4.1 Effect of whiteness on colour reproducibility in bulk dyeing 34 
4.1.1 Bulk trial and colours on the effect of whiteness 35 
4.1.2 Comparison of AE values for each samples 35 
4.1.3 Effect of whiteness of the material to be dyed 39 
vi 
4.2 Effect of pH level on colour reproducibility in bulk dyeing 40 
4.2.1 Bulk trials and colours on the effect of pH level 40 
4.2.2 Comparison of AE values for each samples 41 
4.2.3 Effect of pH value of the material to be dyed 44 
4.3 Effect of absorbency level on colour reproducibility . 
in bulk dyeing 45 
4.3.1 Bulk trials and colours on the effect of absorbancy level 46 
4.3.2 Comparison of AE values for each samples 46 
4.3.3 Effect of absorbency of the material to be dyed 50 
Recommendation and Future work 51 
5.1 Conclusion 51 
5.2 Recommendations on RFT reactive dyeing on cotton knits 52 
5.3. Other dying conditions for colour reproducibility in bulk dying. 52 
5.3.1 Dye bath variables 52' 
5.3.1.1 Condition of steam supply 52 
5.3.1.2 Calibration of thermo meters and pH meters 53 
5.3.1.3 Condition of jet dyeing machine for bulk dyeing 53 
5.3.2 Quality of dyes/ dyeing auxiliaries 53 
5.3.2.1 Water Quality for the dyeing process 53 
5.4 Suggestions for future work. 54 
5.4.1 Correction factor for the pretreated material 54 
5.4.2 Bulk dyeing trials based on separate scouring 
and bleaching process 54 
5.4.3 Preparation of mini bulk -v 54 
Reference List 55 
vii 
List of Figures 
Page No 
Figure 2.1 A sumifix supra dye molecule 7 
Figure 2.2 Dye molecule link with metal ion (M) 9 
Figure 2.3 Compatibility of various types of reactive trichromatic 
dyes for exhaust dyeing 10 
Figure 2.4 The substitution reaction between dye molecule and cellulose 11 
Figure 3.1 Bulk dyeing machine (Ecosoft- serial Number 40940) 19 
; Figure 3.2 Spectrophotometer (DatacolourSF600X) 20 
Figure 3.3 Samples obtained from trail No.Ol 23 
Figure 3.4 Samples obtained from trail No.02 24 
Figure 3.5 Samples obtained from trail No.03 25 
Figure 3.6 Samples obtained from trail No.04 27 
Figure 3.7 Samples obtained from trail No.05 28 
Figure 3.8 Samples obtained from trail No.06 29 
Figure 3.9 Samples obtained from trail No.07 31 
Figure 3.10 Samples obtained from trail No.08 32 
Figure 3.11 Samples obtained from trail No.09 33 
Figure 4.1 Pretreatment process for the regular whiteness 34 
Figure 4.2 Comparison of AE values for trial NO.Ol (Light green) 36 
Figure 4.3 Comparison of AE values for trial NO.02 (Beige) 37 
Figure 4.4 Comparison of AE values for trial NO.03 (Orange) 38 
Figure 4.5 Pretreatment processes for the regular whiteness 40 
Figure 4.6 Comparison of AE values for trial N0.04 (Beige) 41 
Figure 4.7 Comparison of AE values for trial NO.05 (Violet) 42 
Figure 4.8 Comparison of AE values for trial NO.06 (Maroon) 43 
Figure 4.9 Pretreatment process for the regular whiteness 45 
Figure 4.10 Comparison of AE values for trial N0.07 (Light blue) 47 
yiii 
Figure 4.11 Comparison of AE values for trial NO.08 (pink) 48 
Figure 4.12 Comparison of AE values for trial NO.09 (Beige) 49 
^ ^ ^ ^ ^ 
ix 
List of Tables 
Page No 
Table 4.1 Test results for trial No.Ol (Light green) 36 
Table 4.2 Test results for trial No.02 (Beige) 37 
Table 4.3 Test results for trial No.03 (Orange) 38 
Table 4.4 Test results for trial No.04 (Beige) 41 
Table 4.5 Test results for trial No.05 (violet) 42 
Table 4.6 Test results for trial No.06 (maroon) 43 
Table 4.7 Test results for trial No.07 (light blue) 47 
Table 4.8 Test results for trial No.08 (pink) 48 
Table 4.9 Test results for trial No.09 (Beige) 49 
List of Abbreviations 
Abbreviation Description 
MLR Material to Liquor Ratio 
RFT Right First Time 
KPI Key Performance Indicator 
VS Vinyl sulphone 
MCT Mono Chloro Triazine 
AOX Aromatic Organo Halogen 
AATCC American Association of Textile Chemists and Colorists