Torsional Method for Evaluating Hair Damage and Performance of Hair Care Ingredients

The study developed a torsional pendulum method to evaluate hair damage and the performance of hair care ingredients by examining the cuticle and cortex's roles in hair fiber properties. Results showed that fine diameter fibers with a high cuticle-to-cortex ratio exhibited significant torsional deformation and energy dissipation, especially when wet. Hair spray treatments masked the base fiber properties, imparting their own characteristics. Comparing torsional and tensile measurements on over-processed bleached hair treated with Polyquaternium-10 and CETAB, torsional measurements effectively distinguished products reinforcing the cuticle from those affecting the cortex, unlike tensile measurements.