Using a face wash or cleanser can sometimes leave your skin feeling tight, and now a study has revealed why.
Researchers say that although perception of our skin might seem subjective, there is an explanation for the sensation that usually goes away after moisturiser is applied.
The reason for the feeling is the outermost layer of the skin – the stratum corneum – acting as a barrier to keep out unwanted chemicals and bacteria and to keep in moisture, Stanford University scientists found.
Using a harsh cleanser can strip away some of the oils that hold in moisture, causing the skin to contract.
A good moisturiser increases the water content of the stratum corneum, causing it to swell, and provide a relief from that tightening sensation, the research suggests.
Reinhold Dauskardt, of Stanford’s Department of Materials Science and Engineering, said: “This work provides a new understanding of how products affect the physical properties of our skin, which includes not just skin health, but also skin sensorial perception.
“That’s a significant advance.
“It provides a whole new understanding of how to design those formulations.”
The researchers predicted that the mechanical forces created by the shrinking or swelling reach sensory receptors below the skin, which then fire off signals to the brain that we interpret as a feeling of skin tightness.
To test this theory, they studied the effects of nine different moisturising formulas and six different cleansers on donor skin samples from three locations on the human body – cheek, forehead, and abdomen.
Information about changes to the stratum corneum was fed into a model of human skin to predict the signals that the mechanoreceptors would send.
The study found that the predictions lined up almost perfectly with what people reported in human trials for each formula.
Collaborators at L’Oreal Research and Innovation, which funded the study, recruited 2,000 women in France to assess the nine moisturisers and 700 women in China to assess the six cleansers.
The women ranked their perceived feelings of skin tightness after using the formula they were given.
Experts suggest 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.
Professor Dauskardt said: “It provides a framework for the development of new products.
“If you’re doing anything to the outer layer of the skin that’s causing it to change its strain state and its stress state, then we can tell you how that information is transmitted and how it will be understood and reported by consumers.”
The researchers are now looking at the possibility of developing wearable devices to stimulate our senses in a way that allows us to communicate non-verbally.
In the same way that a person reading braille translates sensations on their fingertip into words, a device creating tiny mechanical changes on our skin might be able to convey information, they say.
Prof Dauskardt said: “So now, can we communicate through human skin?
“Can we build a device to provide information to someone non-verbally, non-visually, using our understanding of these mechanisms? That’s one of the areas we’re very interested in.”
The findings are published in the PNAS Nexus journal.
