We often talk about the pH of hair and the products we use to care for it. The pH or hydrogen potential is a measure that determines the degree of acidity or alkalinity of a substance. It is measured on a scale from 0 to 14, with 7 being neutral, less than 7 acidic and greater than 7 alkaline.

Hair, when it is in good condition, has a pH level around 5 or 5.5, so we can say that, like the skin, hair is acidic by nature. The hair shaft has a structure made up of 3 parts: the cuticle, the cortex and the medulla. The cuticle is the outer layer of the hair and protects the cortex. The cuticle is made up of scales that must be protected since they can be damaged by color treatments, perms... The cortex is the most elastic, resistant part of the hair and where melanin is found. The medulla is the innermost part and is made up of keratin.

When the pH of our hair is normalized to levels between 5 and 5.5, the scales that form the cuticle will be closed, so the hair will be healthy, shiny and have elasticity. On the other hand, if the pH increases, the cuticle scales will open and the hair will be dull, rough and with split ends.