Connaître l'acidité de votre peau
- A pH of 7 is equivalent to a neutral pH
- below 7, the pH is acidic
- and greater than 7, basic or alkaline.
The pH of the skin is one of the skin's main protective mechanisms. It is normally slightly acidic, and most often lies between 5.0 and 5.5. It is this natural acidity that protects the skin from pathogenic bacteria. The skin's pH is constantly challenged by external aggressors such as pollution, temperature changes and aggressive products. This causes an imbalance in the skin's pH, leading to changes in skin type and an altered barrier function.
Did you know? Most soaps are alkaline, which over time alters the symbiotic protective flora and the skin's natural hydrolipidic film, making it dehydrated, fragile and more sensitive to external aggression - an obvious source of dermatoses such as allergies, irritations and eczema... It is therefore essential to choose soaps that are gentle on the skin and respect its pH.
Both hair and scalp have an acidic pH. Like the skin, the average pH of scalp is around 5.5 and that of hair around 3.5 when the hair is healthy. This acidity is due to the hydrolipidic film thatkeeps hair hydrated and protects it from moderate chemical and physicalaggression .
Did you know? Hair care products can influence hair pH. A product with an alkaline pH, such as ammonia, will soften the cuticle and open the scales to facilitate pigment penetration during coloring. By pulling the scales apart, products with an alkaline pH deeply damage the hair, making it rough, porous and brittle. They can also increase the hair's negative electrical charge, thereby increasing static electricity. In contrast, a product with an acidic pH will tend to tighten the scales, smooth the hair and leave it shiny.
So, to maintain a healthy scalp and healthy hair, it's best to use a sulfate-free shampoo with a pH of 5.5 followed by a treatment containing cationic agents (conditioning agents) with lower pH to close the scales and reduce static electricity and frizz.