The hair itself does not have a pH value. What we call pH value of hair refers to the pH value of the secretions around the hair.
pH value is the indication of acidity and alkalinity, which refers to how much acidity and alkalinity there are in the aqueous solution. It is expressed as numbers at 25℃. From 0 to 14, 7 is neutral, above 7 is alkaline, below 7 is acidic, and the pH value of hair between 4.5 and 5.5 is the best health state.
Because the hair will open and split when it encounters the alkaline cuticle layer, the hair becomes rough and porous, and the effect of hot dyeing cannot be achieved. The cuticle layer is closed when encountering acid, and maintains a natural pH value of hair of 4.5 to 5.5. The hair has good texture and luster, and it is easy to achieve the effect of hot dyeing.
pH value of hair is 4.5 ~ 5.5
pH of shampoo is 6.5 ~ 6.5
pH of hair conditioner is 2.8 ~ 3.5
pH of perm agent is 8.8 ~ 9.5
pH of hair dye is 9.0 ~ 10.0
pH of seawater is 7.9 ~ 8.5
pH of hair straightener is 11.5 ~ 14.0
In general, the higher the pH value of hair, the worse the hair quality. More than 8 is damaged hair.