Quantifying the Effects of Repeated Dyeing: Morphological, Mechanical, and Chemical Changes in Human Hair Fibers

This study examined the effects of repeated hair dyeing on the morphology, mechanical properties, and chemical composition of human hair fibers using techniques like atomic force microscopy, Fourier transform infrared spectroscopy, and tensile strength measurements. The research found that even a single dyeing session caused noticeable damage, with significant detrimental effects observed after three or more dye treatments. While mechanical properties and protein composition showed non-linear changes, nanoscale damage to the cuticle surface increased proportionally with the number of dyeing sessions. The findings emphasize the importance of considering the health and structural integrity of hair when engaging in dyeing practices.