Most beauty care products and treatments primarily affect the cuticle layers of hair fibers. The resulting damage has an adverse
effect on hair water absorption. Water changes a wide variety of properties of human hair and is therefore of fundamental
interest. Wool proteins are mild, natural, biodegradable, and sustainably produced with multiple functionalities and potential
for use in the personal care and detergent market. In this study, the effect on hair water sorption of two types of keratin
samples obtained from wool is investigated. Modifications of hair water sorption due to a bleaching treatment have been demonstrated,
with lower values of water sorption capacity and an increase of the fibers permeability. Applications of keratin peptides
and proteins to bleached hair improved the water sorption properties of the fibers and reduced their permeability.