Layering sunscreen with facial makeup enhances its sun protection factor under real-use conditions

Benefits of incorporating plant extracts into a commercially available foundation for daily skin use

PURPOSE

This study examined a plant extract (PE) foundation's safety, antioxidant and protective properties. To offer a scientific foundation for the viability of creating 'skincare makeup' and improve the comprehension of cosmetic compositions' efficacy evaluations.

METHODS

Cellular assays tested six different concentrations (up to 5%) of the PE for cell viability levels and reactive oxygen species (ROS) levels of human immortalised epidermal cells (HaCaTs). The identified non-cytotoxic concentration (0.5% PE) was then tested by gene assays. A commercial foundation containing 0.5% PE (PEF0.5) was tested for safety, skin protective effectiveness, and user satisfaction.

RESULTS

Compared to the control groups, 0.5% PE had a significant inhibitory effect on the expression level of MMP-1 but promoted the expression of COL1A1, COL3A1, ELN, and AQP3. PEF0.5 significantly (p < 0.05) reduced wrinkles and transepidermal water loss (TEWL) while improving hydration, glossiness, and elasticity for 14 and 28 days. Interestingly, sebum was reduced by PEF0.5 at 28 days without any negative consequences for 28 days. No significant (p > 0.05) differences were detected in the foundation's effectiveness and usability.

CONCLUSION

Applying PEF0.5 for 28 days may improve the skin barrier function, as indicated by skin TEWL, hydration, wrinkle, elasticity, and sebum content, without any adverse effects.

Visualization of reflectance, transmittance, and application amount distribution of the cosmetic foundation layer on skin

We developed a method for visualization of makeup finishing with structured lighting. By analyzing images with a sequence of projection patterns, reflectance and transmittance of the cosmetic foundation (FD) layer were extracted as spatial maps using the difference between the light spread of bare skin and made-up skin. The spatial maps reflect conditions and distribution of applied FD under real situations. By calibrating the relationship between optical properties and the amount of FD applied, the application amount distribution was also estimated. Additionally, we proposed approximation formulae to estimate the above values without images of bare skin. These formulae provide good agreement with the original formula for reflectance.

Estimation of reflectance, transmittance, and absorbance of cosmetic foundation layer on skin using translucency of skin

We developed a method to estimate the reflectance, transmittance, and absorbance of a layer of cosmetic foundation (FD) applied to skin from the reflectance of bare skin and FD applied to skin under two measurement conditions using the translucency of skin. Conversely, using the relationship between the applied amount of FD and the reflectance of the FD layer, the applied amount could be estimated. These values could be measured stably regardless of the similarity of reflectance and color between bare skin and made-up skin. The measured values were taken from actual skin, which satisfies the condition of actual usage.