Page 64 - Shawl Weaving Artisan - TT

Textile & Handloom Related Theory for Exercise 1.4.35
Shawl Weaving Artisan - Defects and Yarn Quality

Fabric defects, causes and remedies

Objectives: At the end of this lesson you shall be able to
• explain the importance of yarn
• describe testing of yarn
• list various defects and how it causes
• precautions taken for avoiding defects.

Importance of yarn: Yarn is crucial to the textile industry 3 Twist testing
as it forms the foundation for fabrics and plays a key role • Twist tester: Measures the number of turns (Twist
in the durability, comfort, and appearance of textiles. Per Inch or TPI) in a given length of yarn, either
Yarn quality directly impacts the finished product’s single or double yarns.
resilience, texture, and visual appeal, influencing its
performance and lifespan, Additionally, yarn is vital for • Untwist and retwist method: Used to determine
creating specialized textiles with specific functionalities twist direction and contraction in yarn.
like moisture-wicking or flame resistance. 4 Appearance testing

Tests of yarn • Visual inspection: Evaluates color, luster, surface
Common yarn tests: texture, and overall aesthetic appeal of the yarn.
1 Strength testing • Yarn color chart winder: Used to evaluate yarn
color and shade consistency.
• Breaking strength: Measures the force needed
to break the yarn, often determined using methods 5 Other important tests
like the ASTM D2256. • Linear density (Tex/denier): Measures the weight
• Elongation at break: Indicates how much the of yarn per unit length.
yarn stretches before breaking, measured as a • Moisture content: Determines the amount of
percentage of its original length. moisture present in the yarn, affecting its strength

• Tenacity: Calculated by dividing breaking strength and handling.
by linear density, providing a measure of strength • Yarn diameter: Measures the thickness of the
per unit mass. yarn.
2 Evenness testing • Shrinkage: Evaluates how much the yarn shrinks
• Uster quantum: Used to measure yarn evenness, under specific conditions, such as heat or water.
identifying faults like thick and thin sections, and • Yarn on yarn abrasion: Measures the resistance
neps (small knots). of yarn to abrasion when rubbing against other
• Evenness index: A numerical value representing yarns.
the consistency of yarn thickness throughout its
length.

1 Yarn defects
These defects occur due to poor fibre quality or improper spinning techniques.

S.No Defect Description Cause Precautions
1 Slub Thick or uneven lumps in Uneven fiber blending, Use high quality fibers,
the fabric improper roller setting. maintain roller pressure.
2 Neps Small knots of tangled fibers Poor carding process, Improve fiber opening &
appearing as bumps. fiber contamination blending process, maintain
carding machines.
3 Thick and thin places Uneven yarn thickness, Inconsistent spinning Regular tension checks,
causing variations in fabric tension, weak fibers. better quality control in
texture. spinning.
4 Foreign Yarn Stray yarns of different color Yarn mixing during Strict raw material sorting
contamination or type in the fabric. spinning, poor and segregation
handling.

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