What is the pH range of human hair?

The pH range of human hair is generally between 4.5 and 5.5. This slightly acidic pH is important for maintaining the health and integrity of the hair. At this level, the hair cuticle lies flat, which protects the inner structure of the hair and helps to retain moisture, thereby contributing to overall shine and manageability. Additionally, a slightly acidic pH can help inhibit the growth of harmful bacteria and fungi, further promoting hair health.

Understanding the pH of hair is crucial for hairstylists and cosmetologists, as the pH of hair care products can affect the hair's condition. Products with a pH close to this range are preferred because they align with the natural acidity of hair, preventing damage and ensuring that the cuticle remains sealed.