Effects of Permanent Waving on Changes of Protein and Physicomorphological Properties in Human Head Hair

The study investigated the effects of two types of permanent waving (digital perm and croquignole winding perm) and two waving lotions (cysteamine-HCl and sodium thioglycolate) on human hair. It found that permanent waving generally decreased protein content, with the most significant reduction (58%) occurring in hair treated three times with digital perm using sodium thioglycolate lotion. SDS-PAGE analysis identified keratin polypeptides affected by the treatments. Physical properties such as tensile strength, diameter, swelling, and elongation were negatively impacted, particularly with repeated treatments and the use of sodium thioglycolate lotion. Scanning electron microscopy revealed significant morphological changes, especially with repeated treatments using sodium thioglycolate, while a single treatment showed no surface changes.