Impact of Acid Straightener's pH Value on Hair Fiber Properties

The study analyzed the impact of acid straightener products with pH values of 1.0 and 2.0 on hair shaft properties. Tresses treated at pH 1.0 showed a 59.4% improvement in combing tests compared to 33.0% at pH 2.0, but also experienced a greater decrease in tensile strength (16.0% vs. 9.0%) and lower tryptophan content. Differential scanning calorimetry indicated impairment in straightened tresses, and environmental scanning electron microscope images suggested a film formation around the fiber. The study concluded that lower pH values caused more significant modifications to the hair shaft.