If you feel your skincare routine isn't working, don't rush to blame the product; it might simply be that its pH level isn't suitable for you. The skin's pH level affects the absorption and penetration of skincare products, and factors like UV rays, environmental pollution, climate change, and diet can all influence it.

How do we determine if our skin's pH level is normal? Normal skin pH is between 4.5 and 6.5, which is slightly acidic. Our skincare routine aims to maintain this naturally slightly acidic environment. You can use pH test strips to compare the pH of your skincare products with your own. Sebaceous glands, sweat glands, and the skin's normal flora form an acidic outer film on the skin's surface, providing a protective barrier composed of amino acids, lactic acid, etc., thus preventing bacteria and pollution from irritating the skin. Using products with a pH level that doesn't match your skin's will damage this protective layer, making the skin more vulnerable.

Using alkaline skincare products with a pH above 6.5 can impair the skin barrier function, reduce its ability to resist bacteria, and make the skin increasingly dry. In particular, using alkaline soap-based cleansers, even a single use, can cause cumulative damage to the stratum corneum. It can also strip away the skin's surface oils, causing tightness after washing. Those with dermatitis or sensitive skin should be especially cautious when using alkaline products.

Does that mean the more "acidic" the product, the better? Not necessarily. If a product's pH value is below 4.5, it will increase skin irritation. An overly acidic environment will break down physical sunscreens, rendering sun protection ineffective! When choosing sunscreen, the pH value should be between 4.5 and 6.5.

Besides the product's ingredients, what else affects the pH value of skincare products? Due to the principle of water evaporation, the longer skincare products remain on the face, the stronger their acidity becomes. While the skin itself has a buffering effect, makeup removers and cleansers are not suitable for leaving on the face for extended periods.