The importance of pH for the scalp
The pH of the scalp is naturally slightly acidic, between 5.4 and 5.9 when it is healthy. Respecting this balance is one of the keys to healthy hair: that is why pH is a good indicator of the quality of a shampoo or a soap. Here is what you need to know about pH and hair to choose the right product.
What is pH?
pH is a measure of how acidic a substance is, on a scale that generally runs from 0 to 14:
- a pH of 7 is neutral;
- a pH below 7 is acidic;
- a pH above 7 is alkaline (or basic).
What is the pH of the scalp and hair?
A healthy scalp has a pH between 5.4 and 5.9. The hair fibre is even more acidic, with a pH of about 3.67.
By comparison, ordinary soaps have a pH of around 10. That is one of the reasons why it is best to avoid washing your hair with soap or shower gel.
Why does scalp pH matter?
To have healthy hair, it is important to maintain the right pH. The scalp is protected by a slightly acidic hydrolipidic film, and the cuticle scales that form the surface of the hair stay tightly closed in an acidic environment.
When a product that is too alkaline is applied, these scales lift: the hair becomes more porous and rougher, tangles more and loses its shine. The scalp, meanwhile, can dry out, feel tight or react by producing more sebum.
What damages the pH of hair?
Several factors can raise the pH of hair and damage it:
- chemical straightening;
- heat (hairdryers, straighteners, curling irons);
- mechanical stress, such as brushing too vigorously;
- using alkaline solutions, such as soap.
What pH should a shampoo have?
Using a slightly acidic shampoo, with a pH between 4 and 6, can help maintain the scalp's natural balance. Homnès solid shampoos have a pH between 5.5 and 6.5.
Dry or irritated scalp, damaged hair
A shampoo with a slightly acidic pH helps protect a dry or irritated scalp and damaged hair. The nourishing solid shampoo, designed for this purpose, has a pH of 6.25: it gently cleanses the scalp while respecting the hair.
Oily scalp or dandruff
If you have dandruff, the purifying solid shampoo, with a pH of around 5.9, helps relieve these problems, especially when the scalp is oily. For established dandruff, the anti-dandruff solid shampoo is the most suitable. If dandruff persists or comes with irritation, see a dermatologist.
To better understand what is happening on the surface of your head, also read our article on the scalp and how it works. And if you are passing through the Marais, we offer a free scalp diagnosis at the atelier.
In short
- A healthy scalp has a slightly acidic pH, between 5.4 and 5.9; the hair fibre is around 3.67.
- Ordinary soaps, at around pH 10, are too alkaline for hair.
- A shampoo with a pH between 4 and 6 helps preserve the natural balance.
- Homnès solid shampoos have a pH between 5.5 and 6.5.
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