I am using this now. It really works, and it will make the skin delicate. It can also fade spots. No need to add salt, just add a little white vinegar to the clean water after washing your face, soak your face or wash your face with water. It has no side effects and is suitable for long-term use, but the concentration should not be too strong, especially for sensitive skin.

PS: It won't be very sour, it's good and cheap.