Open AccessEnhancing the sweat resistance of sunscreens
Author(s) -
Keshavarzi Fatemeh,
Knudsen Nina Østergaard,
Komjani Niloufarsadat Mirmahdi,
Ebbesen Morten F.,
Brewer Jonathan R.,
Jafarzadeh Shadi,
Thormann Esben
Publication year - 2022
Publication title -
skin research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.521
H-Index - 69
eISSN - 1600-0846
pISSN - 0909-752X
DOI - 10.1111/srt.13115
Subject(s) - ultraviolet , wetting , sun protection factor , materials science , redistribution (election) , uv filter , perspiration , chemistry , chemical engineering , optoelectronics , dermatology , optics , composite material , medicine , physics , politics , political science , law , engineering
Background While sunbathing of performing outdoor sport activities, sunscreens are important for protection of uncovered skin against ultraviolet (UV) radiation. However, perspiration negatively affects the performance of a sunscreen film by weakening its substantivity and uniformity through the activation of two mechanisms, namely sunscreen wash‐off and sunscreen redistribution. Material and methods We used a perspiring skin simulator to investigate the effect of sunscreen formulation on its efficiency upon sweating. Specifically, we modified the sunscreen formulation by incorporating a hydrophobic film former and adding water‐absorbing particles. Sunscreen performance before and after perspiration is assessed by in vitro sun protection factor measurements, direct detection of changes in the sunscreen distribution using UV reflectance imaging, and by coherent anti‐Stokes Raman scattering (CARS) microscopy for microscopic characterization of the UV filter relocation. Results The results show that incorporating a hydrophobic film former can decrease sunscreen wash‐off due to sweating, while an excessive amount of film former might negatively affect the sunscreen distribution. The addition of water‐absorbing particles, on the other hand, had either a negative or positive impact on the sunscreen substantivity, depending on the particle properties. While the addition of large water‐absorbing particles appeared to increase sunscreen redistribution, smaller particles that could form a gel‐like structure upon contact with water, appeared to change sunscreen wetting and sweat droplet spreading, thereby decreasing sunscreen wash‐off and sunscreen redistribution. Conclusions We find that using a combination of hydrophobic film formers, which increase water resistance, and small water‐absorbing particles, which change the wetting behavior, can make sunscreen formulations more sweat‐resistant and less runny.