A novel UV-fluorescence approach to assess the long wear efficacy of foundations.

Background: The long wear properties of foundations are regarded as a must-have in terms of claims. Here, we propose an instrumental approach based on UV-fluorescence imaging as an alternative to clinical grading methods.

Methods: A method was developed, with UV-fluorescence images captured with the Visia CR as a first step, followed by images analysis using Image-Pro plus. Repeated-measures correlation was used to assess the degree of association between the UV-fluorescence method and a grading method when removing the foundation incrementally from the skin using wipes. Thresholds to ascertain whether a foundation pass or fail long-wearing using the newly developed method were established using a mixed linear model and cross-validated using two subsets of a panel of 20 women.

Results: The method could measure incremental removal of foundation using wipes, in a similar fashion to a grading method, as outlined with repeated measures correlation (r = -.86). Pass/fail thresholds established with the mixed linear model were tested versus the grading method when assessing a foundation under real conditions for a duration over 24 hours, with minimal discrepancies between the two methods.

Conclusion: By capitalising on foundation physical/chemical properties, the proposed method allows to assess their long wear properties, irrespective of basal skin tone or foundation shade. It offers the advantage of appealing visuals for efficacy and to be less resource intensive than a clinical grading approach.