Have you ever felt like your skin tightened or weathered after a swim in the ocean? According to a new study, exposure to salt water changes the mechanical properties of human skin and nearly doubles its stiffness compared to fresh water. Led by Guy K. German from Binghamton University, the research was published in the Journal of the Mechanical Behavior of Biomedical Materials.
Decoding the protective barrier of skin
The study aimed to understand why the skin, especially on the face, feels like 'leather' after a day at the beach. Researchers found that the stratum corneum, the outermost layer of the skin, acts like a biological raincoat. It prevents water from escaping the body and blocks harmful substances from entering.
When this thin barrier is damaged, human skin loses its ability to retain moisture. This ultimately leads to that uncomfortable, leathery feeling. The study suggests that salt water can be harsh on this protective layer, Study Finds reported. Guy K German said this should have been figured out in “the 1900s” and added that it’s good to uncover a “gap in knowledge.”
To understand the phenomenon, the research team examined skin samples donated by a 96-year-old woman. The samples were cut into small circles. Half were treated with regular deionized water, and the other half with a saltwater solution matching the average ocean salinity (3.5% salt).
{{/usCountry}}To understand the phenomenon, the research team examined skin samples donated by a 96-year-old woman. The samples were cut into small circles. Half were treated with regular deionized water, and the other half with a saltwater solution matching the average ocean salinity (3.5% salt).
{{/usCountry}}As the samples began to dry under controlled humidity conditions, the team used a specialized microscope setup to observe the changes. By watching tiny fluorescent beads attached to the tissue, researchers measured how much contraction occurred and whether any stress built up during the drying process.
As a result, they found that the skin treated with salt water was nearly twice as stiff as the skin treated with fresh water. Salt-treated skin reached an elastic modulus of 5.13 MPa, while the fresh water-treated skin stood at 2.75 MPa.
Additionally, drying stress was more than double in the salt-treated samples. This type of skin is more prone to cracking, which can allow bacteria to enter the body. According to scientists, sodium chloride has a deliquescence relative humidity of 76%.
FAQs:
1. What was found in the study?
The researchers found that skin treated with salt water was significantly stiffer and more stressed during drying than skin treated with fresh water.
2. How to avoid this?
Guy K. German said the best thing to do is take a shower, as salt water is soluble and can be washed off the skin.
3. Why does the study matter?
The research from Binghamton University confirms that salt water actually makes human skin feel tight and dry.