Film-forming agents: what are they?

Frequently used in cosmetic formulation, film-forming agents are ingredients added to skincare products to enhance their protective effect. They work by creating a film on the skin, nails or hair, helping to slow down water evaporation and restore the hydrolipidic film naturally present on the surface of biological structures. Composed of a mix of water and sebum, this film serves as a barrier; it restricts the entry of pathogens and impurities into the skin, hair or nails while retaining water in the stratum corneum, the cuticle or the nail plate.

Film-forming agents are surface-active substances whose protective and moisturising action takes place outside of biological structures.

The barrier formed by film-forming agents thus allows hair to better resist breakage and be less prone to split ends. At the skin level, the skin gains in elasticity, while the nails remain strong and shiny. In addition to their moisturising virtues, film-forming agents leave a feeling of softness on the epidermis, without a greasy or sticky effect. They also allow for the hydration of hair without weighing it down and the strengthening of nails without softening them.

The incorporation of film-forming ingredients in cosmetic formulation also aids in extending the action of products on the skin, hair, eyelashes, or even nails. Indeed, by providing an adhesive base, they allow balms, lotions, sun creams, or even makeup products to have a better hold throughout the day and to better resist rubbing, humidity, and perspiration. This adhesive action of the film-forming agents also provides more effective control of the release of active ingredients, ensuring uniform distribution and gradual absorption.

Sometimes referred to as texture agents, film-forming agents can be hydrophilic, meaning they have an affinity with water, or hydrophobic, meaning they repel water. Hydrophilic agents, such as carbohydrates, capture water molecules to create a hydrogel and form a hydrated film on the skin's surface. Hydrophobic film-forming agents, such as silicones, mineral or vegetable oils, and waxes, have a more occlusive effect and block transepidermal water loss (TEWL) by opposing water molecules. Some examples of film-forming agents commonly found in cosmetics are presented in the table below.