PHYSICAL PROPERTIES OF SEWING THREADS 
AND THEIR PERFORMANCE 
IN RELATION TO SEAM CONSTRUCTION 
B Y 
C R L G e e g a n a g e 
A dissertation submitted to the Department of • 
Textile & Clothing Technology of the University of Moratuwa 
in partial fulfillment of the requirements of the degree of 
Master of Science 
in 
Textile Studies 
j 
January 2004 ^ 
Department of Textile & Clothing Technnology 
University of Moratuwa
 u m Coll 
Sri Lanka 
79598 
7 9 5 9 8 
The work presented in the thesis in part or whole, has not been submitted for 
any other academic qualification at any institution. 
C.R.L.Geeganage Mr.D.P.D.Dissanayake 
(Candidate) (Supervisor) 
Abstract 
Polyester spun sewing thread is commonly used in high-speed sewing machines 
in the garment manufacturing process. 
Recently core spun sewing threads produced with polyester filament core and 
polyester sheath fibres have been introduced to the local garment industry. 
Poly/ploy core spun thread is believed to give superior quality performance in 
seams. 
The spun polyester and core spun sewing threads are having different structures 
and as such, their properties will be significantly different. 
The behavior of these threads in different types of seams would provide an 
insight to the performance of core spun (poly/poly) and 100% polyester sewing 
threads. 
The results of this research project show that the core spun would give superior 
performance in seams and the thread consumption is less when the core spun 
thread is used. 
ACKNOWLEDGEMENT 
I have great pleasure in declaring my honour to Dr. (Mrs.) Nirmali de Silva, Head, 
Department of Textile and Clothing, University of Moratuwa for the privilege given 
to follow this valuable course. 
I offer my most sincere thanks to my project supervisor Mr. D P D Dissanayake, 
Senior Lecturer for his encouragement, guidance and advice generously given to me 
during the project period. 
I wish to express my gratitude to all the academics of the Department of Textile 
Clothing Technology of the University of Moratuwa for the assistance supporting 
me in various ways for the completion of this project. 
I am much thankful to the Technical officer Mr. H.M. Senevirathe and the other 
non- academic staff members for the assistance me in various ways for the 
completion of this project. 
Special thanks also goes to my friend Kumuduni, my husband and my two babies who 
helped me to complete this project successfully. 
CONTENTS 
C h a p t e r 1 
In t roduc t ion 
L i te ra tu re s u r v e y 
1.1 Seam Definition, Classification and Designation 
1.1.1 Seam Definition 
1.1.2 Seam Designation 
1.1.3 Seam Classification 
1.2 Joining Materials 
1.2.1 Stitching Materials 
1.2.1.1 Sewing Thread Definition 
1.2.1.2 Thread Structure 
1.2.1.2.1 Spun Yarn 
1.2.1.2.2 Mono Filament Thread 
1.2.1.2.3 Multifilament Threads 
1.2.1.2.4 Core Spun Thread 
1.2.1.3 Yarn Twist and its effect on sewing thread 
1.2.1.3.1 Physical Properties of Threads 
1.2.1.3.2 Physical Properties of Cotton Threads 
1.2.1.3.3 Physical Properties of Synthetic Threads 
1.2.1.4 Yarn Numbering and Yarn count systems 
1.2.1.5 Definition of Ticket Number 
1.2.1.5.1 Definition of Cotton Ticket Number 
1.2.1.5.2 Definition of Synthetic (Metric) Ticket Number 
1.3 Surface Characteristics and Appearance of Seams 
1.3.1 Fabric Finishing 
1.3.2 Seam Pucker 
1.3.3 Major factors contributing to pucker 
1.3.4 Performance of Seams 
1.3.4.1 Seam Strength, Extensibility and Elasticity 
1.3.4.2 Transverse Stress and Strain 
1.3.5 Material Failure at the Seam 
1.3.5.1 Seam Slippage 
1.3.6 Thread Failure in the Seam 
1.3.6.1 Linear Stitch Density 
1.3.6.2 Stitch Type 
1.3.6.3 Seam Type 
1.3.6.4 Thread Strength 
1.3.7 Seam Angle in relation to Fabric Structure 
1.3.8 Thread Extensibility 
1.3.9 Durability 
1.3.10 Security 
P a g e No. 
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P a g e No. 
C h a p t e r 2 
Mater ia l s a n d M e t h o d s 
2.1 Scope 
2.1.1 Sewing thread test method 24 
2.1.2 Irregularity (Unevenness )test method 24 
2.1.3 Seam test method 24 
2.2 Sewing Threads 25 
2.3 Conditioning and Testing Atmosphere 25 
2.4 Adjustment of Sewing Machine 25 
2.5 Preparation of Test Specimen 
2.5.1 Cutting 26 
2.5.2 Conditioning 27 
2.6 Test Procedure 27 
C h a p t e r 3 
R e s u l t s a n d Eva lua t ion 
3.1 Calico material 
3.1.1 Fabric specification 28 
3.1.2 Seam strength 28 
3.1.3 Graphical representation of seam strength 29 
3.2 Satin material 
3.2.1 Fabric specification 30 
3.2.2 Seam strength 30 
3.2.3 Graphical representation of seam strength 31 
3.2.4 Graphical representation of seam slippage 32 
3.3 Sewing Threads 
3.3.1 Load and Extension of threads 33 
3.3.2 Linear density and Tenacity of threads 33 
3.3.3 Irregularity of Threads 34 
3.3.4 Graphical representation of Relationship between Type of Sewing 34 
Thread and Breaking Load 
3.3.5 Graphical representation of Relationship between Type of Sewing 35 
Thread and Extension percentage 
3.3.6 Graphical representation of Relationship between Type of Sewing 35 
Thread and Tenacity 
3.3.7 Graphical representation of Relationship between Type of Sewing 35 
Thread and Irregularity of Threads 
P a g e No . 
C h a p t e r 4 
C o n c l u s i o n s 36 
R e f e r e n c e s 37 
APPENDIX 
T e s t R e s u l t s 
A. 1.Seam Strength of Calico material 
A. 1.1 Seam type; Plain seam 
A. 1.1.1 Spun Polyester-Ticket No.: 120 
A. 1.1.2 Spun Polyester-Ticket No.: 180 
A. 1.1.3 Core Spun Polyester-Ticket No.: 120 
A. 1.1.4 Core Spun Polyester-Ticket No.: 180 
A. 1.2 Seam type; French seam 
A. 1.2.1 Spun Polyester-Ticket No.: 120 iii 
A.1.2.2 Spun Polyester-Ticket No.: 180 iii 
A. 1.2.3 Core Spun Polyester-Ticket No.: 120 iv 
A.1.2.4 Core Spun Polyester-Ticket No.: 180 iv 
A. 1.3 Seam type; Lap felled Seam 
A. 1.3.1 Spun Polyester-Ticket No.: 120 v 
A. 1.3.2 Spun Polyester-Ticket No.: 180 v 
A. 1.3.3 Core Spun Polyester-Ticket No.: 120 vi 
A. 1.3.4 Core Spun Polyester-Ticket No.: 180 vi 
A. 1.4 Seam type; Bound seam 
A. 1.4.1 Spun Polyester-Ticket No.: 120 vii 
A. 1.4.2 Spun Polyester-Ticket No.: 180 vii 
A. 1.4.3 Core Spun Polyester-Ticket No.: 120 viii 
A. 1.4.4 Core Spun Polyester-Ticket No.: 180 viii 
A.2. Seam Strength of Satin material 
A.2.1 Seam type; Plain Seam 
A.2.1.1 Spun Polyester-Ticket No.: 120 ix 
A.2.1.2 Spun Polyester-Ticket No.. 180 ix 
A.2.1.3 Core Spun Polyester-Ticket No.: 120 x 
A.2.1.4 Core Spun Polyester-Ticket No.: 180 x 
A.2.2 Seam type; French seam 
A.2.2.1 Spun Polyester-Ticket No.: 120 
A.2.2.2 Spun Polyester-Ticket No.: 180 
A.2.2.3 Core Spun Polyester-Ticket No.: 120 
A.2.2.4 Core Spun Polyester-Ticket No.: 180 
A.2.3Seam type; Lap felled seam 
A.2.3.1 Spun Polyester-Ticket No.: 120 
A.2.3.2 Spun Polyester-Ticket No.: 180 
A.2.3.3 Core Spun Polyester-Ticket No.: 120 
A.2.3.4 Core Spun Polyester-Ticket No.: 180 
A.2.4 Seam type; Bound seam 
A.2.4.1 Spun Polyester-Ticket No.: 120 
A.2.4.2 Spun Polyester-Ticket No.: 180 
A.2.4.3 Core Spun Polyester-Ticket No.: 120 
A.2.4.4 Core Spun Polyester-Ticket No.: 180 
A 3 Thread Irregularity 
A.4 Breaking Strength and Extension of sewing threads 
Spun Polyester 
A.5 Breaking Strength and Extension of sewing threads 
-Core Spun Polyester 
A.6 Linear Density and Tenacity of sewing threads