sewing thread is a flexible, small diameter yarn or strand usually treated with a surface coating, lubricant or both, intended to be used to stitch one or more pieces of material or an object to a material.

1. SEWING
THREADS
Dr. Pooja Singh
Faculty
Footwear Design and Development Institute
Ministry of Commerce and Industry, Government of India
An Institution of National Importance

2. Sewing Thread
• According to the definition given by ASTM, sewing thread is a flexible,
small diameter yarn or strand usually treated with a surface coating,
lubricant or both, intended to be used to stitch one or more pieces of
material or an object to a material.
• It may be defined as smooth, evenly spun, hard-twisted ply yarn, treated by
a special finishing process to make it resistant to stresses in its passage
through the eye of a needle and through material involved in seaming and
stitching operations.

4. • Sewing threads are used in garments, upholstery and geotextiles to
join different components by forming a seam.
• The primary function of a seam is to provide uniform stress transfer
from one piece of fabric to another, thus preserving the overall
integrity of the fabric assembly.

5. • Threads for the high temperature applications are required to withstand and
hold the seams secure in their position in extreme temperature conditions
between 260ºC-1100ºC.
• Threads are usually made from glass, carbon, polytetrafluoroethylene, steel
and aramid fibers.
• Polyesters, Polypropylene, Nylon 6, Nylon 66, are widely used for low
temperature applications such as car upholstery, leather industry, packing
like cement and fertilizer bags.
• Medical sutures are used for wound closure and are specially design and
sterilized to fulfill the end applications.

6. Essential Properties Required for
Sewing Threads:
• Industrial sewing techniques make specific and often very exacting
demands on the threads involved in the sewing process.
• The sewability of sewing threads is of major importance, having a very
profound effect on seam quality and production costs.
• The sewing and the seam performance of a sewing thread are largely
influenced by the material to be sewn, the sewing technique and the end-
use for which the sewn material is intended.

7. These requirements can be defined
as:
1.The ability of the sewing thread to meet the functional requirements of
producing the desired seam effectively.
2.The ability of the sewing thread to provide the desired aesthetics and
serviceability in the seam.
3.The cost of sewing thread and that associated with producing the
desired seam.

8. The different important properties required by a
sewing thread are discussed below:
1. Needle thread must pass freely through the small eye of the needle;
consequently they must be uniform, knot-free and fault free.
2. Tensile strength/breaking strength is one of the essential properties
of the thread. It must be capable of withstanding several kinetic/lateral
movements during sewing.
3. For good performance in a sewing machine moderate to low
extension-at-break of the thread is usually preferred.

9. 4. The elasticity of the sewing thread must be uniform along its length
in order to enable equal length stitches to be formed, and it must
closely match the elasticity of the fabric being sewn; otherwise either
seam thread fracture, or tearing of the adjacent fabric may arise during
garment use.
5. The quantity and quality of finishes are very important.
6. Good abrasion resistance is essential for good sewing performance.
7. Good resistance to heat is a very important requirement of a sewing
thread.

10. 8. The hairiness of sewing thread also affects the appearance of
the seam.
9. The final direction of twist insertion may be important to
enable the stitch forming mechanism of the sewing machine to
perform correctly; most sewing machine require Z twist, but there
are a few where performance is better with S twist.
10. Color fastness is a general requirement for sewing thread. It is
important that the selected shade retain its color throughout the
life of the garment.

11. 11. Low shrinkage during washing and ironing is required.
12. The sewing threads should possess better evenness and should
contain minimal number of knots, faults and neps, etc. Thread
should have very low level of imperfections and faults.
13. Good luster in the thread improves appearance of the seam.
14. Threads must be uniformly dyed in a good match to the
materials being sewn and also the dyed thread should have
properties like colorfastness to washing, light and perspiration.

12. 15. The ability of the thread to perform efficiently
in the sewing machine is defined sewability.
16. Seam puckering can be defined as a differential
shrinkage occurring along the line of a seam and is
mainly caused due to seam instability, due to high
tension imposed during sewing.

13. Geometry of Packages:
S
P
O
O
L

14. C
O
P

15. B
O
B
B
I
N

16. C
O
N
E

17. V
C
O
N
E

18. C
O
N
T
A
I
N
E
R

19. C
O
C
O
O
N

21. DIFFERENT TYPES OF SEWING THREADS
• PTFE coated fiberglass sewing threads
• Alumina-silica sewing threads
• Carbon fiber sewing threads
• Kevlar sewing threads
• Nomex sewing threads
• Stainless steel spun yarn with PTFE or cotton
• Poly propylene sewing thread
• Nylon 6 bonded sewing threads

22. •Nylon 6, 6 bonded filament threads
•Polyester bonded continuous filament thread
•Polished polyester / cotton core spun sewing
thread
•100% spun polyester sewing thread
•High tenacity lubricated polyester braids
•PTFE sewing threads
•Surgical sutures
•Fusible sewing threads