Water resistance is a key performance attribute of sunscreen products, yet its assessment has historically relied on in vivo testing, raising ethical, practical and reproducibility challenges.

This presentation introduces a new physiologically relevant in vitro approach for the determination of sunscreen water resistance. The method was validated through a blinded multi‑laboratory ring test, demonstrating robustness, reproducibility and good alignment with in vivo outcomes.

Beyond the methodology itself, the work illustrates how scientifically sound in vitro approaches can support innovation, standardisation and ethical testing while maintaining meaningful prediction of real‑life sunscreen performance

Objectives:
Conventional in vitro methods for assessing cosmetic appearance benefits typically rely on contact-based measurements, capturing single parameters and generating fragmented datasets. To better characterise the complex visual appearance of surfaces, this study aims to develop a novel imaging instrument capable of integrating multiple appearance attributes within a single, unified measurement for product evaluation.

Methods:
The system utilises imaging-based, non-contact measurement technology combined with a novel LED illumination design incorporating both cross-polarised and non-polarised lighting. A bespoke mechanical framework ensures controlled viewing geometry. Diffuse and specular reflections are separated at the pixel level through digital control, enabling simultaneous extraction of colour and gloss/shine information. Image analysis (IA) algorithms and characterisation models were developed based on calibrated reference targets. The system was evaluated using various in vitro samples, including human hair swatches and Biody skin plates, measured before and after product application.

Results:
The integrated hardware and software system successfully extracted both colour (CIE XYZ and L*a*b*) and gloss-related parameters (e.g., gloss intensity, specular reflection distribution, and coverage percentage) from surfaces in a single measurement. Results of hair swatches showed a significant increase in shine following hair oil application. For Biody skin plates (plain), colour and shine changes after skin cream application were quantitatively detected. Progressive changes in shine for the Biody skin plates (pores) were also measured across treatment stages, from baseline, skin cream, foundation to setting powder.

Conclusion:
An integrated imaging system, encompassing both hardware and software, has been developed. In vitro proof-of-principle studies demonstrate its capability to deliver unified measurements that can be used to support quality control and quantitative product performance claims related to visual appearance. Pixel-level analysis can further enable future assessment of additional attributes, such as texture and translucency, offering a more comprehensive and realistic representation of the total perceived benefits of cosmetic products.

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.

We would like to present our research results connected to the implementation of ISO 23675 SPF in-vitro (“double plate method”) in an industrial research setting, sharing easy-to implement technical refinements, our learnings and potential extensions of the method. From our experience, ISO 23675 offers reproducible SPF in vitro testing with good correlation to in vivo SPF 24444, and empowers reliable screening of new sustainable sun care formulations and ingredients.
Current challenges remain, such as temperature control and potentially certain use cases like formulations with high loadings of water-soluble UV filters or mineral sun care.
We will present our findings to successfully introduce consistent temperature control during irradiation, the identification of certain polyglycerol esters as biodegradable “SPF boosters”, our study into high-PBSA formulations and our approach to mineral sun care. We will also discuss how potential additions to the method could further support the wider implementation of ISO 23675.
We believe that these first-hand results and learnings from an industrial research background will greatly support and inspire others to use ISO 23675 for the scientific advancement of sun care formulation and ingredient development.

Objective:
To quantify the effects of water temperature and tap-running behaviour during routine facial cleansing on skin barrier function, skin physiological parameters, cleansing efficacy, and associated water and energy consumption.

Methods:
In a 10-day, randomised, controlled clinical study, 52 healthy adult volunteers (46 female, 6 male; aged 19–72 years) cleansed their face daily using a Cleansing Balm under one of four conditions: cool or warm water, with the tap either turned off or left running. Volunteers were blinded to the study’s environmental objectives. Water usage was covertly measured using calibrated meters on hot and cold feed pipes, with a thermostatic blending valve for warm water delivery. Skin barrier function (transepidermal water loss (TEWL)), skin moisturisation (Corneometer®), skin pH, radiance and translucency (Diastron TLS-850®), and facial imaging (Canfield Visia-CR®) were assessed at baseline and on days 1, 2, 3, 5, and 10. Makeup removal efficacy was evaluated using colorimetric analysis following application of both light and heavy makeup regimes. Statistical analyses included non-parametric 2-way ANOVA and Wilcoxon rank sum testing.

Results
Warm water cleansing resulted in significantly higher water consumption compared with cool water (P<0.04), with additional increases when the tap was left running. Repeated warm water cleansing caused statistically significant increases in TEWL over time, indicating impairment of skin barrier function, whereas cool water cleansing resulted in minimal TEWL changes. Area-under-the-curve analysis over 10 days demonstrated a significant overall advantage for cool water cleansing compared with warm water for TEWL (P<0.04). Skin pH was significantly lower following cool water cleansing at day 10, while warm water showed no significant change. No statistically significant differences were observed in skin moisturisation, or makeup removal efficacy between warm and cool water conditions. Cool water cleansing resulted in significantly increased skin radiance (P=0.05), whereas warm water was not significant. Environmental modelling demonstrated substantial reductions in water use and associated carbon emissions when cool water was used, particularly with the tap turned off.

Conclusion
Routine facial cleansing with cool water preserves skin barrier integrity, supports a more favourable skin pH, increases skin radiance, delivers effective cleansing performance, and significantly reduces water and energy consumption compared with warm water cleansing. This study demonstrates that environmentally conscious choices can also support improved skin condition, rather than compromising product performance.

Objective:
There is a significant consumer demand for toothpastes that help whiten teeth. Teeth staining is mostly caused by dietary habits and respective extrinsic stains formation.
Comparing different toothpastes whitening claims can be challenging due to variability in test substrate types, dimensions, inter-substrate variability, staining models, etc.
A standardized methodology that quantifies extrinsic stain removal without abrading the surface was developed, by using in-vitro Hydroxyapatite surfaces, as it is human tooth enamel main component.
Stain removal was quantified by CIELab L colour factor (white / black axis) measurements.

Methods:
Different Hydroxyapatite surfaces were tested, using coffee and Yorkshire-tea based-solutions to stain the surfaces at 37 ± 1˚C.
The number of staining cycles needed and type of surface finish (polished or rough surface) were evaluated.
The stained surfaces were brushed with a toothpaste-based dilution and DI water alone, simulating a 3-week teeth-brushing period. The toothpaste prototype used had an abrasive system comprising hydrated silica and calcium carbonate.

Results:
To enable sufficient surface staining, a surface with roughness and a total of four staining cycles were performed. This allowed for the extrinsic stains to adhere to the surfaces. If the surfaces were polished the stains didn’t adhere to the surface.
Following brushing with the diluted toothpaste-medium there was a significant increase in stains removal, as shown by surface whiteness value increase A whiteness increase from 23-129% was noted, depending on the tested surface type.

Conclusions:
In vitro whitening assessment trials by extrinsic stain removal using synthetic substrates would allow sourcing of more homogeneous test surfaces with a bigger surface area.
This laboratory methodology based using in-vitro surfaces could be used for pre-clinical trials product benchmarking screening and claims support.
Keywords
Hydroxyapatite, toothpaste, teeth extrinsic stains, in-vitro test surfaces.