For the health skin, there’s a layer of invisible protective membrane that pH value indicates acidity on its surface.This membrane consists of aqua, olein, cuticle and surface fermentation, and contains vitamin and amino acid.The membrane can prevent skin moisture loss, defend bacterial invasion,and keep skin delicate and fresh.

The new medical research shows that the functions of membrane has important relation with its pH value.If its pH value beneath 4.5 or above 6.0, surface fermentation deviates normal operation and olein layer is damaged so as to weaken the function of moisture loss prevention and bacterial defenses.