The feeling of skin tightness after cleansing may come from mechanical changes at the outer surface of the skin that translate into sensations, according to new research in PNAS Nexus. The study team says understanding the dynamics of the sensation may provide a quantitative approach for determining how people will perceive their skin after using a moisturizer or cleanser.
Harsh cleaners strips away some of the lipids that hold in moisture, causing the stratum corneum to contract. A good moisturizer increases the water content of the stratum corneum, causing it to swell.
Mechanical forces created by this shrinking or swelling are hypothesized to propagate through the skin to reach mechanoreceptors – sensory receptors that turn mechanical force into neurological signals – below the epidermis. These then send signals to the brain that are interpreted as a feeling of skin tightness.
To test their theory, the researchers studied the effects of nine different moisturizing formulas and six different cleansers on donor skin samples from three locations on the human body – cheek, forehead, and abdomen. They measured changes in the stratum corneum in the lab and then fed that information into a sophisticated model of human skin to predict the signals that the mechanoreceptors would send.
The predictions from their analysis lined up almost perfectly with what people reported in human trials for each formula. Collaborators at L’Oréal Research and Innovation recruited 2,000 women in France to assess the nine moisturizers and 700 women in China to assess the six cleansers. The participants ranked their perceived feelings of skin tightness after using the formula they were given.
The ability to understand and predict how people will feel after using a skin treatment could help cosmetics companies improve their formulations before bringing in people to test them. Researchers say this detailed model of how mechanical stresses are transferred through skin layers could potentially be used to evaluate other aspects of product experience.