What is the ideal pH range for shampoo?

The ideal pH range for shampoo is between 4.5 to 5.5. This range is important because it closely matches the natural pH of human hair and scalp, which typically falls within this acidic spectrum. Maintaining a pH within this range helps to keep the hair cuticle closed and intact, thereby reducing frizz and enhancing shine. Additionally, a mildly acidic pH can help maintain the health of the scalp by preventing irritation and promoting a balanced environment for hair growth. Shampoos with a pH outside this range, particularly those that are too alkaline, can lead to damage by raising the hair cuticle, resulting in a rough texture and increased susceptibility to breakage.