Background:
Higher SPF claims in sunscreens are typically achieved by increasing the concentration of UV filters. This approach assumes UV filter performance is both additive and independent of formulation design. This is despite well-documented variation in SPF performance observed between formulations containing identical UV filters and levels.

Objectives:
In this work, we demonstrate that chassis design - including emulsifiers, waxes and film-forming agents - plays a critical and previously under-exploited role in determining photoprotection performance.

Methods:
A systematic formulation screening programme was conducted to evaluate the performance impact of diversified emulsifier architectures across a broad formulation space. More than 100 sunscreen emulsions were developed using fixed base compositions with deliberate variation of emulsifier systems (oil‑in‑water and water‑in‑oil), wax chemistries and complementary film formers to isolate structure–function relationships. Formulations were comprehensively characterised using an integrated analytical approach, including:
• Accelerated stability testing
• Rheology
• Microscopy
• Cryo SEM
• Raman Spectroscopy
• Both in-vitro (ISO 23675) and in-vivo (ISO 24444) SPF assessments
• Both in-vitro and in-vivo sensory assessments

Results:
Microstructural analysis under polarised light identified both spherical and needle shaped crystal morphologies formed via wax-emulsifier co-crystallization. Additionally, multivariate analysis revealed a strong correlation between high-shear viscosity and SPF efficacy, indicating that formulations resistant to deformation enable better UV-filter distribution and, as a result, deliver higher SPF. Advanced imaging demonstrated that film formers enhance UV-filter distribution within sunscreen films, delivering SPF increases of up to 16 units while preserving UVA:UVB balance for international compliance

Conclusion:
These insights allow the creation of completely optimised chassis systems. Combining emulsifiers, waxes, and film formers to deliver robust emulsion frameworks that facilitate the confident delivery of high SPF performance with reduced UV-filter loading. This work demonstrates how formulation science - integrating rheology, microstructure, and ingredient synergy - can transform sunscreen design, unlocking elegant, high-performance sun care solutions that meet consumer expectations for protection and sensory appeal.

Objective
Hair shine is one of the most desirable attributes for consumers, influencing the overall perception of hair health. The interaction of light with hair is complex, consisting of reflection, absorption and scattering all which contribute to its shine or lustre. The overall visual appearance of hair is a combination of lustre, colour and shape. Instrumental shine measurements commonly involve fixing hair tresses onto a cylinder in an aligned configuration, with lustre calculated based on the reflected specular and diffused light. Whilst these methods yield reproducible and robust measurements of technical shine, they are limited to aligned geometries. Hair shape is a principal factor in shine perception, as fibre alignment and hair curvature influence how light is reflected. To address this, we have developed an integrated image-based instrumental method which presents tresses in an unconstrained geometry and enables the measurement of shine across all hair types, textures and styles.

Method
This work presents the development of an Unconstrained Shine Index (USI), a physics-based optical metric. Spectral polarisation imaging is used to separate reflected light into specular, diffuse, chromatic and intensity components. Normalized reflectance components are combined with hair alignment data to generate a single shine parameter.

Results
Shine evaluations were conducted on different hair types with and without a shine enhancing formulation and styling aids. These datasets were explored to evaluate USI results under varying alignment states and natural configurations. The results showed a strong relationship between fibre alignment and high shine. The optical appearance of the hair was reconstructed from the diffuse, specular, chromatic, and intensity components.

Conclusion
This work presents a new unconstrained shine index measurement approach to evaluate shine across all hair types with relevance for textured and highly curled hair where traditional shine methods are limited.