The Structural Implications of Water Hardness Metal Uptake by Human Hair

The study investigated the impact of water hardness metals, specifically calcium and magnesium, on human hair. It was found that hair can absorb significant levels of these metals from tap water, especially after chemical treatments. The uptake of these metals was shown to depend on the hair's condition, with chemically damaged hair absorbing more even from soft water. The metals primarily concentrated in the cuticle layers, affecting the hair's structural properties. The presence of these metals caused fibre stiffening in both virgin and bleached hair, reduced combing forces, and influenced style retention. Virgin hair showed improved style retention, while bleached hair experienced a slight reduction.