The ratio of VC to water starts from 5: 100, and can be increased to 10% after more than a week. It takes at least one month for the concentration of 10% to jump to 15%.

The following points should be noted:

First, the concentration of VC solution should not exceed 20%. If the concentration is too high, the skin's absorption of VC will decrease.

Second, the PH value of VC solution is low, so be careful when using it. Start with a low concentration, such as 5%.

Three: cream or propylene glycol can prolong the storage period of VC and help VC penetrate into the skin. If you can't buy propylene glycol, you can use the cream at home instead. Four: the prepared VC solution should be kept in a brown bottle. The formula with propylene glycol can be stored for one week, but it can only be stored for 24 hours after adding water.