What are exfoliants and why they enhance the action of cosmetics

Dermatology and aesthetic medicine have demonstrated that, by removing the keratinized cells of the stratum corneum, the skin activates a process of deep renewal and rapid improvement of the surface appearance. This method, commonly referred to as peeling, has evolved over the years thanks to the discovery and testing of new acids and their targeted vehiculation.

In fact, these practices are already described in very ancient treatises on traditional medicine that report recipes based on sulfur, pumice and other mineral or vegetable powders. But it is only at the end of the 1800s that begins the use of trichloroacetic acid, salicylic acid, and resorcinol, in skin topicals.

We know that the process of cell renewal slows down as the years go by, and so cells «dead» tend to «cement» on the skin surface and that their increased permanence results in increased opacity with reduced elasticity and overall skin hydration.
Promoting epidermal turnover not only means encouraging the elimination of these devitalized elements, but also stimulating the basal layer to synthesize new cells. In doing so, the skin understands that it needs to reproduce itself with speed… and it does!

The difference between scrub and peeling

Unlike scrubs and scrub, which involve a mechanical action through the rubbing of particles (granules, spherules, fine powders or salts), the cosmetic peeling promotes a deeper effect, homogeneous and can be targeted to certain areas or extended to the entire face, décolleté, hands and why not, even the forearms, to get even total body peeling.
Technically, we speak of keratolytic activity, that is, reduction of corneocyte cohesion through direct action on the junctions between cells (desmosomes). The acids favor the detachment and removal of corneocytes deposited on the surface and, at the same time, stimulate the renewal mechanisms.
Evidence of this process can be of the «dandruff» type, where the microlamels in the skin break off
such as dandruff, or unraveling, when thin flaps of skin peel off like the skins of a fruit, a process that is evident after sunburn.

Today, chemical peeling is one of the treatments of excellence to reduce the signs of aging and treat keratosis, acne scars, stretch marks, rosacea, dyschromia, hyperchromia, acne, seborrheic dermatitis and radiodermatitis.
The study of the different acids, their concentration and pH, not only offers the aesthetic doctor a range of options to act in a targeted manner on the individual diseases to be treated, but also extends to the use at home, either to prepare the skin for a professional peeling, or to replace it in the long term. Let’s take a brief look at these fantastic treatments to get a clear and precise overview.

The depth of action

The «professional» peels can be classified according to the depth they reach based on the type of problem to be treated. We therefore distinguish:

  • very superficial peelings: they reach only the stratum corneum;
  • superficial peelings: they reach the superficial epidermis;
  • medium to deep peeling: they reach the thorny layer of the epidermis;
  • deep peelings: they reach the basal layer.

The characteristics of acids

Alpha-hydroxy acids (AHA): the most common ones in cosmetics are lactic acid, glycolic acid and mandelic acid. Alpha-hydroxy acids (also known as fruit acids) are considered substances of natural origin, although they can be reproduced synthetically.

Glycolic acid is abundant, for example, in sugar cane, grapes and beet. Alpha hydroxy acids have aroused particular interest for the regenerating action they perform on the epidermis. In particular, the already mentioned glycolic acid, concentrated at 4-5%, has a predominantly moisturizing effect; at concentrations higher than 8-10% it starts to show, instead, a smoothing activity. Due to its chemical characteristics and higher molecular weight, mandelic acid penetrates more gradually and uniformly through the skin compared to other alpha hydroxy acids. This makes it less irritating than, for example, glycolic acid, and more suitable for sensitive or acne-prone skin.

Beta-hydroxy acids (BHA): these include salicylic acid at limited concentrations, an active ingredient used above all to carry out superficial peeling in the treatment of acne. Salicylic acid is characterized by strong keratoplastic (exfoliating) and smoothing properties. Applied to the skin, it causes exfoliation of the superficial layers of the skin and is very effective in eliminating keratin plugs and freeing comedones (white and blackheads) from sebaceous content. It also performs a bacteriostatic, drying and soothing action without causing irritation.

Fruit acids are also widely used in cosmetics for their antioxidant properties. The name of these particular types of acids derives from the fact that they are present in great quantities in fruits. Among these, we can mention: malic acid from apples, tartaric acid from grapes, glycolic acid from sugar cane, citric acid from citrus fruits, mandelic acid from almonds, etc.
Fruit acids are particularly suitable for oily skin, especially if it is asphyxial, because they allow sebum to escape from the follicle more easily, thus avoiding the formation of furuncles and comedones (white and blackheads). For this purpose, non-oily and delicate exfoliating products should be used; it is known, in fact, that the sebaceous glands react to similar insults by increasing the production of sebum.
Generally, with the use of products containing fruit acids in low concentrations, the results are appreciable after a couple of weeks of regular use. Generally they have a good moisturizing power.

The degree of acidity expressed in pH

As we know the neutral pH — neither acid nor basic — is equal to 7.5. Going down from that number we find the scale that also indicates the aggressiveness of the substance. For example, lemon has a pH between 2.3 and 2.5 and acetylsalicylic acid has a pH up to 4.
For strong skin exfoliation, acids with a pH no higher than 3 are used. For moderate exfoliation for home use, however, a pH of 4 can give excellent results.

We often talk about buffered formulas. What does this mean? It means that the normal pH of the ingredient, for example, of a pH 2 glycolic acid, is made less aggressive by adding salts to the formula that soften it and make it more manageable and safe. As I always explain in my courses, we have to distinguish the medical act, which controls the live skin reaction and allows the use of products that reach the dermis, from the home use of exfoliating formulas, which follow the «maximum yield-minimum expense» principle, where by expense I mean the induced skin reactivity.

The action time

How long should exfoliants be left on the skin? My recurring word is: it depends!
The factors that need to be considered are the type of skin, the result that is desired and the type of acid that is used. Without going into professional protocols, we can distinguish formulas that must be rinsed after 5/10/15 minutes to interrupt the action of keratolysis and formulas that can remain in contact with the skin because they alone complete the exfoliating action in due time.

What to do — and not to do — after a peel

In the post-peeling course, it is essential to protect oneself from sunlight and UVA-UVB lamps with products containing sun filters to prevent possible post-inflammatory hyper pigmentation. It goes without saying that one should not expose oneself directly to the sun or use tanning lamps. It may seem an obvious advice but it is not.

A good product that boasts an SPF 30 used regularly and reapplied throughout the day will offer excellent safety performance. Mineral or chemical filters are different options, but attention must be paid to the vehicle, especially in skin with acne tendencies: it must be thin and non-comedogenic.

The results

After exfoliation through home cosmetic peeling, the skin texture is visibly refined and regains its natural luminosity, as well as being more receptive to the functional substances present in the treatments that will be applied subsequently.

We can say without doubt that peelings enhance the action of all protocols, as they make the skin barrier sufficiently permeable to the passage of subsequent actives. They are considered true «pathfinders». The home peeling clinic shows that the weekly application of a good exfoliant:

  • qualitatively improves dermal tone;
  • stimulates the epidermis in depth;
  • exerts an anti-aging action by attenuating the visibility of signs associated with skin aging, such as fine lines, smoothing the epidermis;
  • helps minimize hyperchromia by eliminating hyper pigmented corneocytes;
  • softens scars and mild acne marks.

Fabio Callegari
Training Consultant