How to exfoliate your skin. Skin exfoliation and peeling.

We all know the importance of good cleansing, toning and moisturizing routines for our skin.

But exfoliating your face on a regular basis can improve the results and help to rejuvenate your skin.

The stratum corneum (Latin words for 'horny layer') is the outermost layer of the skin. This layer is composed of 15-20 layers of flattened cells and varies in thickness from approximately ten to several hundred micrometres, depending on the region of the body.  The purpose of this layer is to form a barrier to protect underlying tissue.  It is composed of layers of dead, flattened keratinocytes surrounded by a lipid matrix, which together act as a brick-and-mortar system.

But horny layer is also very important from an aesthetical point of view. The properties of this layer influence the skin appearance because they involve skin texture and light reflection.

The horny layer continually undergoes natural exfoliation, due to its cells (corneocytes) renewal. However, if the cell turnover is slowed down because of aging or environmental aggressions, skin texture is impaired resulting in roughness and thickening of the horny layer.

There are two ways to exfoliate skin: 1) mechanical and 2) chemical, depending on the exfoliant agent.

The first way is the mechanical exfoliation. This is achieved by using products (scrubs) or devices that are mildly abrasive to mechanically slough off dead skin cells, revealing a fresher dewy complexion.

Exfoliation by mechanical abrasion has been proven to deliver similar skin anti-aging effects to that of retinoic acid (Marks R, et al.)

SmithW.P. equally demonstrated that removal of the superficial layers of the stratum corneum (SC) by tape-stripping induced many of the skin anti-aging effects compared to lactic acid and retinyl palmitate.

There are a variety of exfoliant materials available for the bath and body industry.  And you can find all natural ingredients for exfoliation at your local supermarket (or on the shelves of your kitchen). 

- Sugar

- Oatmeal

- Baking soda

- Coffee

- Ground nuts

- Salt

For facial exfoliators, choose a milder exfoliant to avoid the risk of broken blood vessels. I do not encourage anyone to use an exfoliant that consists of larger particles, or more harsh on the skin, than fine dead sea salts.

The second way is the chemical exfoliation, i.e. chemical peeling.

Chemical exfoliation consists of application of certain substances on the skin, which attack the cell junctions in the horny layer through enzymatic mechanisms or acidic pH. 

The exfoliation effects of acids have been especially investigated for the treatment of xerosis but it was not until 1989 that the anti-wrinkle effects of cosmetic use levels were recognized and first commercialized in 1992. Inducing horny layer turnover was thought to be a major anti-aging action of these acids especially with concentration increase and a lowering of pH.

The level of penetration, destruction and inflammation determines the level of peeling in the dermatological clinics. Considering chemical structure, exfoliating substances that are most often used in cosmetology contain alpha-hydroxyacids (glycolic acid, lactic acid, mandelic acid and citric acid), beta-hydroxyacids (salicylic acid) and other organic acids, such as trichloroacetic acid and pyruvic acid.

At home chemical peeling products should be formulated within the usage range of 0.1 to 12%, with a pH between 4.0 and 4.5. Please be aware that when you use  Alpha-Hydroxy Acids on the skin you are exposing new skin, which is much more susceptible to UV damage. Always follow with an adequate sunscreen. 

Referance:

- R.Marks, S. Hill and S.P.Barton,  British Journal of Dermatology (1990) 123, 457-466.

- Smith W. Stratum corneum barrier integrity controls skin homeostasis. Int J Cosmet Sci 1999; 21(2): 99–106.

- van Scott EJ, Yu RJ. Cutis 1989; 43: 222–228.

- Smith WP. Epidermal and dermal effects of topical lactic acid. J Am Acad Dermatol 1996; 35(3): 388–91.