When we think of the soaps we have at home, we can only think about the foam that produce. From the hands to the hands to shampoo, up to the detergents for the dishes, almost everyone produces a quantity of foam that seems to confirm the foam-pulicy relationship. Even the name “shower gel” suggests how an integral part of our daily cleaning experience are. It is difficult, in fact, to imagine a bath in the tank without soap bubbles. But what exactly does the formation of foam depend on when we use soap? The answer lies in its chemical composition, in particular in the surfactants. These molecules, responsible for the cleaning action of soaps, not only facilitate the removal of dirt, but are also involved in the formation of a stable and lasting foam. At this point, it could be said that all soaps, being composed of surfactants, form the same amount of foam. In reality it is not so. Some soaps make more foam than others. How is it possible? Depends on several factors, including the quantity and type of surfactorybut also the presence of further substances capable of drastically increase or decrease the amount of foam, or not by promoting the production of the characteristic soap bubbles depending on the use to which the product is intended.
How the soap foam is formed and why
The foam is formed when air is trapped in a liquid where they are present surfactantsgenerating the characteristic spherical shape of the bubbles. This phenomenon is easily observable: for example, just shake some water when we bathe in the pool and we will see bubbles appear. However, in the absence of particular molecules, the foam formed is not very long lasting, on the contrary, It vanishes practically immediately. This happens because in the liquid there are no i surfactantsthe characteristic molecules of soap.
The surfactants have a unique structure, consisting of two parts: one “head“Hydrophyla that gets along with water and a”tail“Hydrophobic that prefers everything that is not water, such as fat or air. When we wash our hands dirty with soap and water, the surfactive molecules are arranged with the hydrophilic head near the water and with the hydrophobic tail near the fat to take away, thus cleaning our skin. The same principle applies to the formation of foams.
When the air enters the water where there are surfactants, the hydrophobic queues will position again as far as possible from the waterthen towards the air entered the liquid, inside the bubble. The surfactants act as a sort of barrier which prevents the air trapped from escaping. The result is one longer lasting and resistant foamwith the bubbles that remain intact longer than those formed in a liquid without the help of surfactants.

Why are some soaps “more foamy” than others?
The presence of surfactants in all types of soap could suggest that the foam is always generated in abundance, regardless of the product. In reality, the level of foam and its duration depend not only on the presence of surfactants, but also on amount. A good number of these molecules makes the product more foamy, while a reduced quantity leads to the formation of less bubbles. Also the type of surfactant makes the difference. For example, dishes detergents, formulated mainly with anionic surfactants, produce abundant foam thanks to the highly foamogenic nature of this class of molecules. On the contrary, other products may contain surfactants with a Low foaming powergenerating a less abundant and more “fragile” foam.

Companies carefully monitor the level of foam generated by their products, adapting it to the specific needs of use. In the case of the washing machine detergent, for example, an excessive foam could hinder the effectiveness of washing, since the internal agitation of the appliance already produces abundant foam. For this, they are added anti -crusher agents To limit its production: they are often mixtures of silicones, silica gel or vegetable oils.
In body care and scalp products, the final consumer tends to perceive foam as a synonym for cleaning, despite some studies suggest that a greater amount of foam does not better the cleaning of the product, And a good amount of bubbles is therefore requested. To satisfy these expectations, they are added Agents who amplify the production of foam: These are non-ionic surfactive and surfactive mixtures such as SDS (for s-dodecil sodium sulphate friends) and dodecilbenzenesenexolfonate and other molecules with high-sounding names that are added for example in the shampoo, even if the bubbles are not so essential for cleansing.