Synopsis

This study introduces a new method to evaluate how well sunscreen formulations spread on the skin and how this affects their Sun Protection Factor (SPF).

Over 100 formulations have been developed and tested using a novel in-vitro spreadability technique involving robotic application and image analysis. A strong correlation between poor spreading, uneven UV filter distribution (measured via Raman spectroscopy), and low SPF performance was found. Conversely, well-spread formulations showed higher SPF and better UV filter distribution.

The findings validate this new technique as a reliable tool for improving sunscreen formulation by enhancing spreadability, which in turn boosts UV protection.