PROCESS IMPROVEMENT IN DENIM WASHING 
T WICKRAMASINGHE 
A dissertation submitted to the department of 
Textile & Clothing Technology of the University of Moratuwa 
In partial fulfillment of the requirements for the degree of 
MASTER OF SCIENCE IN TEXTILES STUDIES 
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Department of T e x t i l e * Clothing Technology UN Thesis 
University of Moratuwa 
Sri Lanka "7 9 S 
January 2004 
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The work presented in die thesis in part or whole, has not been submitted for 
any other academic qualification at any institution. 
f^-uX -^ 7) 
T.Wickremasinghe N4r. V.A. Nandasena 
(Candidate) (Supervisor) 
ABSTRACT 
This research study is primarily concerned with exploring the avenues for improving the 
denim washing process while minimizing environmental pollution and satisfying 
customer expectations. Since denim washing itself is involved with processing of dyes 
and chemicals that affect the environment, a total prevention of pollution cannot be 
expected. On the other hand denims are customer driven products and more fashionable 
out looks are always demanded and of which end result could also be producing a lot of 
impacts to the environment. So that it is necessary to control the washing processes and 
take every steps to minimize industry wastes and environmental pollution by employing 
alternative applications with learned limitations on the products and washing processes. 
This research attempts to examine process improvements in denim washing in three 
directions; product quality, process quality and environment pollution. In order to 
enhance customer satisfaction, garment quality is to be ensured against customer's stated 
and unstated needs while monitoring the washing process. The contributory factors in 
determining the quality of process are cost reduction, productivity improvement, waste 
minimization, optimum use of resources etc. In case of pollution prevention, water 
conservation, reuse of chemicals, waste minimization, waste recovery, effluent control, 
control of environmental hazards etc. are examined. 
This study shows the means of increasing the quality of garments and productivity of 
processes. It proposes the use of bio-degradable enzymes in place of harmful chemicals. 
In case of preventing environmental pollution, fully compliance to legal requirements and 
regulations draws high priority. Above all, creation of an awareness on customer trends 
and behaviour, denim washing, use of chemicals and enzymes, washing conditions etc. is 
essential. 
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LIST OF CONTENTS 
Page 
1 . I N T R O D U C T I O N 1 
2 . D E N I M W A S H I N G P R O C E S S 
2.1 Denims 3 
2.2 Washing Process 5 
2.3 Washing Process Stages 6 
2.4 General Procedures for Different Washes 16 
2.5 Process Improvement 20 
3 . M E T H O D O L O G Y 26 
4 . F I N D I N G S A N D A N A L Y S I S 
4.1 Wash Types and Recipes 28 
4.2 Water for Denim Washing 30 
4.3 Effects of Washing on Denims 32 
4.4 Process Modifications and Improvements 38 
4.5 Environmental Discharges 46 
4.6 Waste water Treatment Process 48 
4.7 Work Environment Hazards 50 
5. C O N C L U S I O N S A N D R E C O M M E N D A T I O N S 5 3 
R E F E R E N C E S 5 7 
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LIST OF FIGURES AND TABLES 
Page 
Figures 
2.1 Denim washing process stages 6 
2.2 Cellulase enzyme reaction on cellulosic fibre 9 
2.3 Oxidation of indigo through bleaching 13 
2.4 Oxidation pathway of Indigo through enzyme bleaching 14 
2.5 Quality Plan for washing of denims 21 
2.6 Pollution Prevention Model 24 
2.7 Waste flow diagram 27 
4.1 & 4.2 Wash comparisons 40 
4.3 Wastewater Treatment Process 49 
T a b l e s 
2.1 Desired colour effects 17 
2.2 Stone washing 18 
2.3 Enzyme washing 18 
2.4 Ice (Acid) washing 19 
4.1 Chemical Analysis of raw water 31 
4.2 Defects analysis of garments 33 
4.3 Washing defects, their causes and solutions 34 
4.4 Strength loss 37 
4.5 Resource Utilization 43 
4.6 Environmental discharges from denim washing 47 
4.7 Effluent discharges with limits 48 
4.8 Measurement of Noise, Heat and ventilation levels 52 
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4. 
ACKNOWLEDGEMENT 
At the outset I am very grateful to Mr V A Nandasena, Chairman/Managing Director, 
Vantex (Pvt) Limited, Dehiwela and Visiting Lecturer of the Department of Textile and 
Clothing Technology, University of Moratuwa, who is also the Project Supervisor for the 
invaluable guidance and the encouragement given to me with extreme patience and 
understanding. 
I acknowledge with a deep sense of gratitude the assistance extended by all the lecturers 
and the staff of the University, during my studies and preparation of this research paper. 
Finally I wish to extend my appreciation to my colleagues and close associates who 
guided and assisted me in numerous ways to end up this research study with success. 
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