Shampoos and conditioners that are pH-balanced have about the same pH level as hair, which is typically between 4.5 and 5.5. This indicates that the pH level of hair is acidic, which is true for any pH level less than 7.
The pH level is important in hair care. For instance, if a hair stylist colors a customer's hair, the hair's pH level often rises to 9 or higher so that the hair cuticle accepts the color well. After coloring, the stylist treats the hair again to return it to its normal pH; however, if the customer shampoos and conditions at home with products with pH levels too high for hair, the color washes out more easily.