TLDR Internal lipids in keratin fibers, like wool and hair, reduce water absorption and release.
The study evaluated the water adsorption and desorption behavior of keratin fibers, specifically wool and human hair, with and without internal lipids. It was found that the isotherms for these fibers exhibited a characteristic hysteresis between uptake and desorption. Wool fibers had lower diffusion coefficients compared to hair fibers, which was attributed to the higher proportion of ceramides in wool lipids, leading to reduced water penetration. Lipid extraction increased diffusion coefficients, highlighting the role of lipids in maintaining water permeability. The study used the GAB model to analyze variations in monolayer sorption capacity, emphasizing the importance of internal lipids in the water sorption properties of keratin fibers.
254 citations
,
January 2007 in “Chemical Society Reviews” Hair is a complex protein fiber with unique properties useful for developing hair products.
50 citations
,
March 2001 in “Clinics in dermatology” Human hair is complex and grows in cycles starting from embryonic life.
10 citations
,
January 1994 in “Cosmetics and toiletries” Ceramide treatment can strengthen and protect hair from damage.
75 citations
,
November 1965 in “Textile research journal” Papain and bisulfite break down human hair by dissolving parts of it.
2 citations
,
July 2023 in “Cosmetics” Surfactants in shampoos and conditioners remove some but not all lipids from hair, and more research is needed to understand their full impact.
21 citations
,
March 2017 in “Skin research and technology” Removing external lipids from hair reduces moisture and increases strength, while removing internal lipids decreases water permeability.
September 2025 in “Cosmetics” Lipid content and structure affect water absorption in different hair types.
7 citations
,
March 2019 in “Journal of cosmetic dermatology” African hair has the most lipids, while Caucasian hair is more hydrated and stronger.
10 citations
,
November 2016 in “International Journal of Cosmetic Science” A tough membrane between the outer and inner layers of human hair protects it from damage.
