Cosmetic peeling is a famous mechanism of action intended for improving the quality of the skin surface. It relies on a well-known skin feature: the continuous renewal of the epidermis and its consequence, flaking. The most superficial cells of the stratum corneum are regularly removed and replaced with other cells newly formed in the underlying layers
If this phenomenon is hindered or curbed, horny cells can accumulate, which contributes to creating more or less discreet hyperkeratosis, which in turn leads to a skin disorder, like dry or rough skin. This is called retentional skin. Several factors like aging or environmental conditions can interfere with this cycle, leading to the same type of symptoms, which makes it worth trying to regulate it. And this is what products called “scrubs” or “cosmetic peelings” are aimed at. Peelings are carried out according to different methods, none of which is significantly better than the others. Here are more details.
The oldest method is most probably “scrubbing”: it consists in delaminating the skin’s upper layers with abrasive substances. This action almost automatically triggers a natural renewal process and helps improve the epidermal turnover, leading to horny parts being removed. Products called scrubs or exfoliating creams belong to this category. And the substances used include plant-based powders, fruit pips or seeds, but also often kernels, like the “renowned apricot kernels”, clays, and ingredients like salt crystals, sugar, and sodium bicarbonate. Recycled coffee beans derived from coffee pods were recently awarded a prize.
This technique dates back to the ancient Egyptians for the practice of exfoliation. In the Middle Ages, wine was used as a chemical exfoliant, with tartaric acid as the active agent. The Greeks used sand as an exfoliant. In Asia, the practice of exfoliation began hundreds of years ago. The etymology of the word “exfoliate” comes from the Latin “exfoliare” to strip the leaves.
In the modern time, one milestone in this field was the well-known apricot scrub by Aapri (Gillette group) launched in the late 1980s (1988), soon rivalled by Saint Yves (by Unilever). Despite – or because of – quite huge a commercial success, their safety was soon questioned, in particular following misuses.
Then, the search for alternatives led to a new approach: scrubbing grains used as exfoliating agents were replaced with synthetic agents, like polyethylene beads, which were soon widely used in cosmetics.
Many products followed this formulation model in the 1990s and later on. But it is all over! Following criticisms on their environmental impact, these substances were gradually banned. In France, the Biodiversité law validated on July 20, 2016 provides for the ban on polyethylene beads in cosmetic products starting from January 2018. Now, in 2020, plastic microbeads have almost all been replaced by plant-derived powders. Ingredient suppliers have developed a rich offering, and a simulator even helps choose the best quality!
This scrubbing action can also be carried out with accessories, like exfoliating gloves: simple cotton washcloths or the renowned massage glove. The latter needs to be moistened before scrubbing the body – preferably – or facial skin (but then it should be used most gently). The kessa glove is another possibility: in the Middle East, this rough glove is traditionally used for exfoliation treatments in association with black soap. It was originally made of animal hairs, but it is now usually composed of viscose derived from plant-based fibres. Green exfoliation also exists, thanks to the Konjac sponge
based on the roots of the eponymous plant: it is 100% natural and biodegradable. One can also mention the Luffa sponges: Luffa is an exotic cucumber which gently and deeply cleanses the skin.
As far as products are concerned, skin-softening preparations have almost always existed. It has been reported that during the Ancient times, the Greek rubbed their skins with a mixture of oils and sand which they then removed with a curved metal scraper called strigil. Now, if exfoliation used to be associated with foaming body products (black soap in traditional practices), preparations became more specific in the second part of the 20th century. The following were once successful – some of them are still pretty well-known, though: Pâte Grise from Payot in 1947, 7 Day Scrub Cream Clinique in 1968, Doux peeling from Clarins , and more recently, Crème Exfoliante by Embryoliss. This list is far from exhaustive.
Skin exfoliation can also be obtained with a chemical and/or enzymatic action. Peelings described as “superficial” involve chemical exfoliating agents which interfere with dead cells sticking both to the skin and to one another. They are usually used on the face. But peelings can also have a deeper action, depending on the exfoliating agent used and on the dose. When they involve a very well-known dermatological technique called “deep peeling”, they remove most calluses. This technique requires a mixture of acid substances, like lactic acid or glycolic acid at high concentrations combined with phenol. At first, it was only used in medical centres. Then, starting from the late 1980s, it was transposed to cosmetics: but in this field, it is carried out more gently and moderately, by strongly reducing the concentration of agents or removing some of them (phenol). The substances used are known as alpha hydroxy acids, or AHAs, or beta hydroxy acids (BHAs), as a consequence of their chemical structures – the carboxylic group being either in the alpha or beta position. The main acids are glycolic (or hydroxyacetic acid), lactic, malic, and sometimes citric acids. It is worth mentioning that they are all water-soluble substances. If limited to concentrations lower than 10%, and if the pH value is adjusted, these products do provide an action on the epidermal turnover. Their presence in certain natural formulas led to their being called “fruit acids” or “flower acids” – it sounds more poetic, but it does describe the same substances. One of their main characteristics is that they leave the skin stinging when the product is applied. This sensation is not associated with irritation, but with a sensorial, perfectly well-tolerated and harmless phenomenon. Several products were initially developed on this segment, like Millenium, by Élisabeth Arden.
Launched in 1980, this product was clearly claimed to help accelerate epidermal renewal. And it featured an original test to visualize the effect created thanks to a fluorescent marker, Dansyle chloride, which measured the renewal time by impregnating the stratum corneum. Later, tests based on DHA method (Dihydroxyacetone) were developed. Also in the US, “Doctor brands” took over the concept with the Obagi range – a first based on this approach. In Europe, brands waited, as the potentially irritant effects of AHAs compelled them to remain cautious. European products were placed on the market in 1992. With Day Lift, Chanel was one of the very first brands to offer something on this segment. And soon, new, gentler AHAs were developed. By fixing the acids onto a fatty chain, the acid function was transitorily blocked, reducing the penetration, while maintaining a sufficient exfoliating activity.
The enzymatic pathway consists in using proteolytic enzymes that interfere with the adherence of horny cells to one another for easier removal. The main substances used are papain or bromelain, but the enzymes should still be properly stabilized in the vehicles used.
Lastly, this process can also be triggered through the biological pathway, which involves substances that help trigger the epidermal renewal process. Most biological activators or biostimulants offer this property, and several substances were proven to improve the epidermal turnover, like Gatuline® Renew by Gattefossé. This anti-aging active is extracted from an Asian plant, Cryptomeria japonica. Its terminal parts, the buds, are where the plant’s metabolism is the highest, and it is also where primary metabolites can be found (sugars, amino acids…) – this high source of energy and nutrients revitalize the epidermis. Plus, these buds contain many secondary metabolites, in particular a guaranteed content in polyphenols and isopimaric acid.
This concept was also adopted about twenty years ago by Sanofi, using extracts from specific yeast to trigger skin renewal. They created a product called Stimulogic, but it was not much successful. These products already foreshadowed the wave of what is now called postbiotics.
A few plant-based substances can also produce the same effect: for example, a LVMH’s recent publication deals with an ingredient offering an original mechanism of action to this aim.
More recently, instruments making it possible to more or less completely exfoliate the face skin have emerged. These techniques are described in a book coordinated by Vincent Faivre, entitled Conception des produits cosmétiques – Formulations innovantes.
Starting from page 248, you can find details about new techniques, from cleansing brushes to microdermabrasion, and even ultrasonic cleansing.
Conclusions (to date!!!)
Products involving these techniques have long existed in different forms: anhydrous products, in particular for enzyme-based formulas, powders, creams, emulsions, and lotions, like the base product in the original Clinique range. Over the past few years, Clinique have sold enough of their Lotion Clarifiante to reach eleven times the Eiffel Tower’s height if the products were piled up. Plus, we should not forget about a few products that have almost disappeared, like exfoliating creams (Doux Peeling by Clarins…), or a few exfoliating lotions which have unfortunately vanished from the market.
No doubt new specialties based on this process will soon emerge. As usual, it is never too late to do the right thing or improve what already exists, maybe reinventing old product.
Jean Claude LE JOLIFF
To know more : Références biblio Peeling
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