What is Skin Acidification?

Skin acidification refers to the reduction of the skin's pH through application of acidic products in order to optimize skin health and physiological functions. pH stands for the ‘power of hydrogen’ which is a scale to determine the skin acidity or basicity. The skin has a pH gradient with the underlying layers of the skin around neutral or pH 7 and the upper layers or stratum corneum gradually reaching pH 4.5-5.0. Above the top layers of the skin resides a thin acidic film called the acid mantle created from sebaceous and sweat excretion. The acid mantle acts as a barrier to bacteria and other contaminants.

Importance of Skin Acidification

Skin surface pH differs with age, gender, race, anatomical position, circadian rhythm, the amount of sebum on the skin, skin moisture and sweating.1 A lot of factors can contribute to the change in pH such as environmental factors, diet, cosmetics, etc. The function of the stratum corneum is to form an effective barrier between the dry, external environment and the interior of the body. This barrier is pH dependant and an acidic pH is necessary to maintain its competency against various insults.2 The acidic surface pH is also an important determinant for the growth conditions of both resident microflora, i.e., normally found on the skin, as well as transient microflora, i.e., opportunistic, potentially pathogenic.3

Skin Acidification in Skincare

The pH of the skin surface increases with age and results in reduced epidermal barrier function. Aged skin needs appropriate skin care to counterbalance age‐related pH increase and improve barrier function.4 To prevent skin from a higher pH, cosmetic companies are formulating buffer products with an acidic pH to improve skin barrier and physiological function. A study in 2019 found that treatment with a pH 4.0 formulation significantly improved stratum corneum integrity in the elderly. The beneficial effects on the stratum corneum coincided with a significantly lowered skin pH and improved skin hydration.4 Reducing the skin’s pH has known therapeutic effects for atopic dermatitis and acne vulgaris as well. Common acids used in skincare are BHAs (beta hydroxy acids) and AHAs (alpha hydroxy acids). They are naturally occurring in plants and have exfoliating effects on the skin. AHAs are water soluble and typically affect the surface layers of the skin while BHAs are oil soluble and penetrate the hair follicles and deeper skin layers.

Skin Acidification in Natural Deodorant

Armpit skin has a higher pH making it a perfect environment for odor causing bacterial growth. A lot of the natural deodorants consist of baking soda which is an alkaline substance which may cause irritation to the skin. pH balance is essential in deodorants. Saltair formulates its skincare deodorants with two focus ingredients: salicylic acid and zinc ricinoleate. Salicylic acid (BHA) has antimicrobial properties and plays a role in reducing the skin pH, making it a difficult environment for bacteria to grow. It aids with the exfoliation of the upper skin layers and hydrates the skin. It also helps visually reduce hyperpigmentation, lightening darker armpit skin areas to help even skin tone. The exfoliating property helps prevent hair from getting trapped thus minimizing the potential for ingrown hairs. The other major ingredient, zinc ricinoleate, is a fatty acid found in castor seed oil that acts as an odor neutralizer. It traps and chemically absorbs odor volatile molecules that can cause malodor. Nourishing oils and algae are additionally added to contribute moisturizing elements. Saltair deodorant is formulated for all skin types including sensitive skin.