With bright blond hair colors becoming more fashionable in recent years, prevention or even repair of hair damage by lightening has become a strong consumer need. Leading edge research of structural changes in keratin caused by strong oxidative stress has led to several approaches how to counteract this oxidative damage by ingredients capable to form bonds between adjacent keratin chains. An overview presents several ingredients used already in market products acting via different mode-of-actions of keratin bonding. For the class of organic di-acids experimental evidence is given, showing protection of keratin during oxidative damage perceivable also by consumers. Results of tensile strength evaluations as well as multiple grooming tests and differential scanning calorimetry (DSC) and finally test salon evaluations support the hypothesis that certain di-acids like maleic acid or succinic acid are able to bridge adjacent keratin chains via ionic interactions and/or hydrogen bonds.