A yarn defect is any irregularity or abnormality in yarn structure, appearance or cleanliness that deviates from the required specification. Yarn defects directly affect fabric quality, appearance, strength, dyeing behavior and garment performance.
Yarn Defects
Major Types of Yarn Defects
1. Twist Variation
Twist variation occurs when yarn has inconsistent twist levels along its length.
Yarn Twist Variation
Over‑twist: Yarn is too tight
Under‑twist: Yarn is too loose
Causes
Improper ring frame or rotor settings
Fluctuating spindle speed
Drafting system instability
Poor maintenance of twisting elements
Effects on Fabric
Over‑twist:
Harsh handle
Reduced absorbency
Poor dye penetration
Under‑twist:
Weak yarn
Frequent yarn breakage
Excessive hairiness and pilling
Control Measures
Regular twist measurement (TPM/TPI)
Proper spindle speed control
Balanced drafting system
Routine machine calibration
2. Count Variation
Count variation refers to uneven yarn thickness along its length.
Yarn count Variation
a) Thick Places
Localized increase in yarn diameter
Causes fabric streaks and barre effect
b) Thin Places
Localized reduction in diameter
Causes yarn breakage and weak spots
c) Neps
Small entangled fiber knots
Appear as white or dark specks after dyeing
d) Slubs
Intentional or unintentional thick places
Uncontrolled slubs are defects
Causes
Poor carding and combing
Improper drafting
Contaminated raw cotton
Roller slippage
Effects on Fabric
Neps Yarn
Uneven dyeing
Barre or streak marks
Reduced fabric strength
Poor visual appearance
Control Measures
Proper carding and combing settings
Autoleveller usage
Uster evenness monitoring
Raw material quality control
3. Foreign Matter Contamination
Foreign matter refers to unwanted materials mixed into the yarn.
Common TypesForeign Matter Contamination yarn
Polypropylene (PP) fibers
Jute fibers
Colored fibers
Plastic pieces
Dust and seed coat fragments
Causes
Contaminated raw cotton
Poor housekeeping
Improper bale handling
Recycling waste contamination
Effects on Fabric
Visible specks after dyeing
Shade inconsistency
Fabric rejection by buyers
High claims in white or pastel shades
Control Measures
Manual cotton sorting
Optical yarn clearers
Foreign fiber detectors
Strict mill housekeeping
4. Stain in Yarn
Stains are localized discolorations on yarn surface.
Types of StainsStain in Yarn
Oil stains
Grease stains
Rust stains
Water or chemical stains
Causes
Machine oil leakage
Dirty transport surfaces
Improper storage
Water contamination
Effects on Fabric
Dyeing spots
Shade variation
Poor fabric appearance
Unacceptable for light shades
Control Measures
Oil‑free machine maintenance
Clean material handling
Proper storage conditions
Immediate removal of stained packages
5. Hairiness (Grade 5)
Hairiness refers to protruding fiber ends from the yarn surface.
Hairiness
Measurement
Measured using Uster Hairiness Index
Graded visually or instrumentally
Causes
Short fiber content
Low twist
Poor carding/combing
Worn machine parts
Effects on Fabric
Fuzziness
High pilling tendency
Poor print clarity
Reduced abrasion resistance
Control Measures
Increase twist within limits
Use compact spinning
Improve fiber selection
Singeing at fabric stage
6. Snarl (Grade 3)
Snarling is the tendency of yarn to form loops or coils due to excess twist and torque.
Snarl yarn
Causes
High twist insertion
Unbalanced twist direction
Improper winding tension
Effects on Fabric
Knitting defects (loops, dropped stitches)
Uneven fabric structure
Production stoppages
Control Measures
Proper twist balance
Use of anti‑snarling devices
Controlled winding tension
Steam relaxation where applicable
Yarn Defect Grading (Visual Standards)
Yarn defects are often graded using visual boards or reference standards (e.g., Grade 1–7), where:
