Every time I see someone posting about mixing baking soda in their face wash or applying lemon juice on their face, I feel like holding them by their shoulders and telling them, "Stop! You are destroying your skin's barrier."
What exactly is a skin barrier, you may ask?
The skin barrier, also known as lipid barrier, protects us from harmful substances in the air. The acid mantle is key to the skin's protective barrier. It neutralizes the alkaline-based aggressors (such as harsh surfactants), inhibits the growth of bacteria and restores and maintains the optimal acid environment - in which skin's natural flora can grow - but we destroy it by using things that are actually harmful for us by being extremely high or low in PH. PH stands for "potential hydrogen" and is used to describe the acid-alkaline ratio of a substance, which ranges from 0 (the most acidic) to 14 (the most alkaline). Skin is more acidic than alkaline and the ideal PH varies around 4.6 to 6.

Most of us do not realize that the PH of our skin has a lot of relevance in its overall health. The outermost layers of our stratum carenum/moisture barrier have an acidic PH that can range from 4.0-6.0. This is also known as the "acid mantle", which plays an important role in the condition of our skin. The acid mantle's low PH serves to stop the growth of harmful bacteria, fungi, parasites, and other pathogens, as well as maintain the durability and structural integrity of the keratin proteins in our keratinocytes: dead skin cells comprising, primarily, of a structural protein called keratin. These cells contain water-soluble compounds, known as natural moisturizing factor (NMF), that maintain hydration. With harsh treatments, we start depleting this NMF and destroy our lipid barrier.
When we use products with a high/alkaline PH, we are disrupting our skin barrier or acid mantle. Alkaline products cause the keratin proteins to soften, and as they lose their structure, they also lose their protective qualities. When our acid mantle is disrupted, our skin becomes prone to infection, acne, roughness, flaking, irritation and dehydration.

8 Signs that prove your skin's pH is too high
1. After using a regular (not very harsh) cleanser, your skin feels tight and dry.
2. You need to moisturize your skin at least once a day.
3. You have suddenly developed sensitivity to products you regularly use, including makeup and creams.
4. You sometimes notice your skin has dry, flaky, rough patches.
5. You usually notice your skin is looking duller and has more lines in the mornings.
6. Your skin has become excessively oily and is more prone to breakouts, whereas it wasn't in the past.
7. Your skin stings often and turns red after applying products.
8. Your skin does not look plump, moist and dewy anymore.

Remedy:
Take a close look at how much (and how often) you're cleansing, scrubbing and hydrating. You need to make sure that your skin can ward off the damaging factors that are making it look older than it should.

8 Signs that prove your skin's pH is too low
1. After using a regular (not very harsh) cleanser, your face feels slightly oily or not clean.
2. You never moisturize.
3. Your skin has become sensitive and reacts to everything, including makeup and creams.
4. You usually notice your skin has dry, flaky, rough patches.
5. On rare occasions, your skin looks duller and has more lines in the morning.
6. Your skin is excessively oily and prone to breakouts whereas it wasn't in the past.
7. Your skin stings often, turns red and also gets irritated.
8. Your skin looks plump, but it is greasier rather than dewy.

Remedy:
Simply stop OD-ing on chemical peels and harsh scrubs.

6 Signs that prove your skin's pH is just right
Those with a PH on the lower end of the 4.0-6.0 scale have greater overall skin health.
1. After using a regular (not very harsh) cleanser, your skin feels soft and smooth.
2. You are moisturizing at least once in the morning as well as evening.
3. Your skin is never dry, flaky and there are no rough patches.
4. Your skin has never looked dull or had lines in the morning.
5. Your skin feels normal to products you regularly use, including makeup and cream.
6. Your skin is not excessively oily or prone to breakouts.