TLDR Cuticle damage doesn't affect hair's tensile strength; the cortex is responsible for it.
The study investigated the effects of diperisophthalic acid on human hair fibers, specifically focusing on cuticle damage and tensile properties. Microscopic analysis revealed significant cuticle damage, yet there were no detectable changes in the tensile properties of the hair, whether wet or dry. These findings supported the hypothesis that the tensile properties of human hair are primarily due to the cortex, with minimal or no involvement from the cuticle. Despite the cuticle constituting approximately 22% of the hair fiber's cross-sectional area, its damage did not affect the hair's tensile strength, indicating that tensile properties are mainly an index of cortical integrity.
20 citations,
January 2015 in “Journal of cosmetic dermatology” Older people's hair cuticles get more easily damaged and lose protective oils, especially in their 40s and 50s.
42 citations,
April 2008 in “Acta materialia” Different ethnicities and treatments affect human hair strength and structure.
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December 2007 in “Acta materialia” AFM helped show how hair changes under tension and the effects of damage and conditioner.
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March 2005 in “International Journal of Cosmetic Science” The torsional method effectively evaluates hair damage and the performance of hair care ingredients.
72 citations,
July 2003 in “Journal of cosmetic dermatology” Frequent hair coloring and styling can damage hair and cause breakage or loss.
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July 2001 in “Clinics in dermatology” Proper haircare and communication with doctors are key to managing hair loss and avoiding damage.
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March 2001 in “Clinics in dermatology” Bleaching damages hair, making it rougher and weaker.
86 citations,
January 1996 in “Clinics in dermatology” Hair can be damaged by daily routines, but protein-based products can protect and improve it.