What causes split ends in hair?

What Causes Split Ends in Hair

Split ends form primarily through mechanical stress from grooming procedures, with damage accumulating from repeated combing, brushing, and manipulation of the hair shaft, particularly when hair is already weakened by chemical treatments like bleaching. 1, 2

Primary Mechanical Causes

Grooming-Induced Damage

• Combing and brushing create the most significant mechanical stress, causing both short segment breakage (less than 2.54 cm from the tip) and longer segment breakage higher up the hair shaft 3
• Repeated elongation, torsion, and flexion actions during daily grooming progressively damage both the cuticle and cortex of the hair fiber 2
• Tangles and knots generate particularly severe stress, as hairs loop around other hairs or comb teeth, creating concentrated force points that initiate splitting 1, 3
• Dry combing produces more short segment breaks near the tips through "end wrapping" caused by inertia and static charge, while wet combing causes fewer tip breaks but more long segment breaks higher up due to increased friction and lower breaking load from water plasticization 3

Progressive Damage Mechanism

• The splitting process follows a predictable sequence: cuticle sliding → failure of the cuticle-cortex interface → nucleation of intercellular cracks at the cuticle-cortex junction → propagation of cracks toward the surface → final breakage when cracks merge 2
• In low-quality hair prone to splitting, cracks originate inside the hair strand and propagate longitudinally over considerable distances, whereas in healthy hair, splits originate at the surface and remain short 1
• Mechanical damage accumulates over time, creating internal cracks that eventually result in breakage at unpredictable sites along the hair shaft 2

Chemical Damage as Contributing Factor

Bleaching and Chemical Treatments

• Chemical bleaching significantly increases both short and long segment breakage during combing, making hair more susceptible to split ends 3
• Chemical hair straightening can damage the cuticle structure, though it may provide some temporary cosmetic improvement in appearance 4
• Bleaching changes the mechanical behavior of healthy hair, making it behave similarly to low-quality hair that naturally experiences splitting 1

Hair Type Considerations

Curly and Textured Hair

• Curly hair experiences higher breakage rates due to the combination of structural differences and grooming-induced stresses, with 96% of African-American women reporting breakage in one large study 2
• The repeated mechanical stresses from managing curly hair affect both cuticle and cortex components differently, leading to accelerated failure 2

Important Clinical Caveats

• Split ends cannot be permanently repaired - they can only be temporarily mended with specialized polyelectrolyte complexes that create a crosslinking structure, but these wash out with shampooing 5
• The only definitive solution is trimming the damaged ends, as once the cuticle-cortex interface fails and internal cracks form, the structural integrity cannot be restored 2
• Continuous preventive care throughout the hair's life cycle is essential, as damage accumulates progressively from the moment hair emerges from the scalp 2
• Hair conditioners can decrease both short and long segment breakage during combing, providing some protective benefit against split end formation 3