Cleansing to clean the skin without irritating it

Cleansing is something that we all do several times a day; indeed, it’s precisely because it is such a matter of routine that it often fails to receive due attention. In fact, it is important to remember that proper cleansing should clean the skin without irritating it. In a word, it has to be balanced: respecting the skin’s characteristics and parameters as much as possible.


The verb cleanse literally means “to rid of impurities”, and indeed cosmetic cleansers serve to remove the dead cells of the stratum corneum and secretions such as sebum and sweat from skin and hair, as well as dirt from the surrounding environment.

Cleansing is also a question of hygiene; after all, it is the first step in keeping our bodies clean and fresh. 

In general, dirt is lipophilic in nature, meaning that it has an affinity for fats and oils. This means that water alone, even when hot, is not sufficient to remove it effectively.

So, it is essential to use some special substances together with water to increase its affinity for such dirt, thereby increasing its effectiveness as a cleanser.

Depending on the action mechanism of these substances, the result may be cleansing by affinity or cleansing by contrast.

Cleansing by affinity: what does this mean?

Cleansing by affinity means cleansing with oily substances, in accordance with the “like dissolves like” principle. Such cleansers consist of lipid components which solubilise “oily dirt” — environmental impurities, sebum, sweat — by affinity, thus removing them from the surface of the skin. This type of cleanser does not form a lather when combined with water, but rather results in a milky emulsion.

This form of cleansing is the most delicate by far, because it leaves the hydrolipidic film unaltered. It also has an important soothing and protective effect on the skin and scalp. This makes it ideal for the delicate skin of newborns, children and the elderly, and in cases of irritation and inflammation caused by skin problems.

Cleansing by contrast: what does this mean?

Cleansing by contrast is based on substances called “surfactants”. These molecules have a dual affinity, consisting of one part with an affinity for fats and oils (lipophilic) and one part with an affinity for water (hydrophilic). The lipophilic part captures particles of dirt, sebum, sweat and impurities from the environment, which are “oily” in nature, while the hydrophilic part means they can be rinsed away.

As the name suggests, surfactants act on the surface, where they lower the tension — i.e. the repelling effect — between water and dirt so that the latter can be removed from the skin or hair and washed away.


The first surfactant used in history for cleansing skin is without doubt soap. In chemical terms, a soap is a sodium or potassium salt of fatty acids, also known as an anionic surfactant.

Soaps grew so popular that this became the name of the product itself. In other words, a soap is a substance which contains soaps as surfactants.

In modern times, not only is soap produced on an industrial scale, but other types of surfactants have begun to emerge. These are obtained through synthesis and are called “syndets” for short, an abbreviation of “synthetic detergent”.

One for all and all for one: Marseille soap

From the Arabs to the Mediterranean, the traditional recipe for soap made exclusively from vegetable oils is still considered ideal for cleansing all types of skin, even the most sensitive.

Soap is produced through a process called saponification. The process begins with fatty acids, such as those from coconuts and olives, which undergo a chemical reaction with a strong base, such as soda or potash, chosen to produce the desired final consistency.

By its very nature, soap has an alkaline pH value, i.e. a value greater than 7, and greater also than skin pH. So, why would a cleansing product like this be considered ideal for skin? Because the pH of a cleanser is not particularly relevant in determining its suitability; in fact, the degreasing power of the surfactants count for much more. Soap, particularly if enriched with substances such as glycerine, has a much lower tendency to degrease — and thus deplete — the skin than, for example, a cleanser which has a pH of 5 but is based on highly aggressive surfactants.     

Surfactants: friends or foes of your skin?

Surfactants are important ingredients in all types of cosmetics because, again due to their dual affinity for water and oil, they can perform different functions: some are solubilising agents, many are emulsifiers necessary for producing milks and creams, while others have wetting, foaming and cleansing properties.

In fact, the main system for classifying surfactants is based on the charge of the hydrophilic part. The classifications are: anionic surfactants, with a negative charge; cationic surfactants, with a positive charge; amphoteric surfactants, with a dual charge; and neutral nonionic surfactants. Cleansing products use anionic, amphoteric and nonionic surfactants in particular, while cationic surfactants are used in hair conditioners because of their conditioning effects.


Some anionic surfactants which produce a lot of lather, such as SLS (Sodium Lauryl Sulfate) and SLES (Sodium Lauryl Ether Sulfate), tend to be more aggressive. In fact, in addition to removing dirt, they also carry away the hydrolipidic film, depriving the skin of its natural defences and thus leaving it more vulnerable to external aggression and irritating substances.

But not all surfactants are the same!

In fact, some surfactants, even anionic ones with a similar structure to SLES, are much less aggressive and — another important factor — are never used alone in a cleanser. For balanced cleansing, a combination of surfactants must be used, producing a small amount of lather as well as a cleansing effect which respects the skin.

Cleansing the scalp

When we use shampoo, we're washing more than just our hair! Above all we are washing our scalp, a very special area of the skin which contains 100,000 hair follicles and, of course, the same number of hairs and sebum-producing glands.

Just like the skin on our body, our scalp also needs cleansing for hygienic reasons, but can suffer from dryness, irritation, itching and dermatitis. Therefore it is extremely important to take care of it on an everyday basis, using cleansing products which clean effectively without irritating the scalp.

When it comes to shampoo, the most common products are those which cleanse by contrast, based on surfactants; but oil-based shampoo formulas are also available, which cleanse by affinity and are recommended for cases of itchy or irritated scalps and as local treatment for cradle cap.