The shampoos that have been messing with women's heads are shampoos with a neutral pH. This wave guarantees beauty and protection to the tresses, in addition to better conserving modern treatments, all because this shampoo has the property of not harming the hair, is it true? Is there a scientific explanation for this fact?
Before explaining how shampoos help in hair treatments, let's see what the hair structure consists of. A strand of hair contains molecules that bind in different ways, the structure of the hair changes with the binding.
There are basically three forms of molecular bonds present in hair: salt bridges, hydrogen bonds and disulfide bonds. The shampoo's secret is right here: changing the interactions that form the hair.
For example, let's see how to change the look just by wetting your hair. Have you ever noticed that wet hair tends to remain without volume? People with unruly hair use this property to create a more pleasant look, but the problem is that when dry, the hair returns to its initial position.
The scientific explanation for this fact is that when the hair strands are wet the hydrogen bonds present break, but when drying these bonds are formed again. It was based on this theory that shampoos with neutral pH emerged.
When hair is washed with an acid shampoo (pH ≈ 1.5), in addition to the hydrogen bonds, the salt bridges are also broken, resulting in unruly and dry hair. And it's no use looking for a shampoo with a high pH (pH ≥ 8), these are the worst, as they are responsible for the appearance of the famous double ends, due to the breakage of the disulfide bridges present at the ends of hair.
So what is the ideal shampoo to keep your hair strong and healthy? It is recommended to use shampoos with a pH between 4.0 and 5.0 (moderate pH). Based on this information it is possible to formulate an ideal shampoo for your hair, in addition to learning more about pH it will also gain a new look.
Do not stop now... There's more after the advertising ;)
By Líria Alves
Graduated in Chemistry
Brazil School Team
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Would you like to reference this text in a school or academic work? Look:
SOUZA, Líria Alves de. "Shampoo pH and hair chemistry"; Brazil School. Available in: https://brasilescola.uol.com.br/quimica/o-ph-xampu-quimica-cabelo.htm. Accessed on June 28, 2021.
