The pH of hair is important for its overall health and appearance. Understanding this chemical balance helps in maintaining strong, shiny, and manageable hair. This understanding helps in recognizing how products and environmental factors impact hair and scalp.
Understanding the pH Scale
The pH scale measures how acidic or alkaline a substance is, ranging from 0 to 14. A pH of 7 is considered neutral, like pure water. Values below 7 indicate increasing acidity, while values above 7 signify increasing alkalinity, also known as basicity. For instance, lemon juice is acidic (around pH 2), while bleach is highly alkaline (between pH 11 and 13). Each whole number on the pH scale represents a tenfold change in acidity or alkalinity, meaning even small pH shifts can have substantial effects.
The Natural pH of Hair and Scalp
Healthy hair is naturally slightly acidic, falling within a pH range of 4.5 to 5.5. This acidity helps keep the hair’s outermost layer, the cuticle, smooth and closed, protecting the inner hair shaft and preventing moisture loss and damage. The scalp also maintains a slightly acidic environment (around pH 5.5), forming an “acid mantle” that inhibits bacteria and fungi, safeguarding follicles and preventing irritation or dandruff.
How pH Influences Hair Health
Deviations from hair’s natural, slightly acidic pH can impact its health. When hair products are too alkaline (high pH), they cause the hair cuticle to swell and lift. This compromises the hair’s protective barrier, making it porous and susceptible to damage. Hair can become dry, frizzy, dull, and prone to breakage and split ends as it struggles to retain moisture and proteins. Chemical treatments like coloring, bleaching, perms, and relaxers are highly alkaline to open the cuticle for processing, leaving hair vulnerable if not rebalanced.
An overly alkaline environment also disrupts the scalp’s acid mantle, leading to issues such as dryness, itchiness, and irritation. This imbalance can affect the scalp microbiome, contributing to conditions like dandruff.
Conversely, excessively acidic conditions (low pH) can also be damaging. A pH that is too low can cause the hair cuticle to contract too tightly, leading to stiffness and brittleness. Such conditions can also irritate the scalp and, for color-treated hair, may alter the color or accelerate fading.
Tips for Balanced Hair pH
Maintaining balanced hair pH involves thoughtful product selection and care practices. Choosing shampoos and conditioners specifically formulated as “pH-balanced” (within the 4.5 to 5.5 range) helps align with hair’s natural acidity. These products help keep the hair cuticle smooth and intact, preventing moisture loss and frizz. Thorough rinsing after washing is also beneficial to remove product residue. Avoiding harsh chemicals and overly alkaline hair products, such as some strong dyes or relaxers, can minimize pH disruption.
If chemical treatments are used, follow-up care aimed at restoring hair’s pH can help reseal the cuticle and reduce damage. Diluted acidic rinses, such as apple cider vinegar, can be used occasionally to help close the cuticle and restore pH after cleansing. Applying aloe vera gel can also help bring down hair’s pH and fight frizz. These practices support overall hair integrity, leading to smoother, shinier, and more resilient strands.