Evaluation of Hair Fibers Properties Treated with Acid Straightener at Different pH Values
April 2019
in “
Digital Library of Theses and Dissertations (Universidade de São Paulo)
”
TLDR Hair straightening at pH 1.0 improves alignment but weakens hair more than pH 2.0.
The study evaluated the effects of an acid hair straightener, specifically glyoxylic acid combined with carbocysteine and amino acids, on hair fibers at pH values of 1.0 and 2.0. It was found that hair treated at pH 1.0 showed better cuticle alignment and straightening ability, with improved combability (59.4%) compared to virgin hair, while pH 2.0 achieved 33.0%. However, the tensile strength decreased by 16.0% at pH 1.0 and 9.0% at pH 2.0. Hair color change was more pronounced at pH 1.0, and tryptophan content was lower. Both pH treatments altered hair structure, and UV exposure caused more cuticle damage but offered some protein protection. Repeated applications improved fiber alignment and sealing but increased rigidity and breakage risk, highlighting the importance of pH in hair straightening and damage.