Prevention and Repair of Damage during Hair Relaxing
Alkaline hair relaxers used to straighten excessively curly hair, usually African-American hair, often cause considerable hair amage. One of the effects of straighteningthe hair with relaxers is a loss in tensile strength due mainly to breakage of disulfide and hydrogen bonds. This loss in tensile strength leaves the hair more susceptible to breakageand cuticle erosion from subsequent grooming. The damaging effects of relaxer treatment are not limited to disulfide bond breakage alone. Another cause of hair damage during relaxing is swelling of hair fibers during the highly alkaline treatment. During a conventional hair relaxer treatment, the hair swells by 50% or higher, and another 20% upon rinsing. When hair swelling is not controlled, the hair develops radial and longitudinal cracks again rendering the hair susceptible to breakage from combing and brushing. This study presents results on the application of cationic polymers to strengthen hair during relaxing, and non-ionic polymers which control hair swelling.
Water-soluble and water-dispersible polymers are widely used in the cosmetics industry in general, and in hair-care products in particular. Natural water-soluble polymers such as starches and gums have been used in hairstyling products for thousands of years.
Early formulations used for setting and styling hair were generally aqueous solutions or hydroalcoholic gels of polymers such as Gum Arabic, Karaya gum, shellac, and alginates. These early mucilage-based concoctions were heavy and became tacky when exposed to humidity in the atmosphere.