Why SPF testing methods matter: ISO 23675 and the future of in vitro sunscreen validation

SAES Getters | Black woman shielding her face from sunlight with a screen – symbolizing ethical SPF testing and in vitro sunscreen validation under ISO 23675

Why reliable SPF testing is a real challenge

For formulators and R&D teams, developing high-performance sunscreen formulations is about more than selecting active ingredients — it’s about proving effective, measurable protection under the strictest global standards, while balancing sensory profile, filter load, and sustainability.
Traditionally, the most recognized methods for measuring SPF and UVA-PF are in vivo protocols, such as ISO 24444:2019 (SPF) and ISO 24443:2021 (UVA-PF).

These methods rely on human volunteers — and in the case of SPF, involve controlled UV exposure to induce erythema (sunburn) as a means to assess protection.
While widely used, these protocols raise concerns about ethics, cost, and reproducibility — especially as the demand for cleaner, more sustainable SPF innovation grows across the industry.

How the new ISO standards change the game

In recent years, two new standards were approved: ISO 23698 and ISO 23675.
Both aim to offer an alternative to in vivo testing — but they work in different ways:

ISO 23698 still involves human volunteers but uses a more ethical approach: instead of inducing erythema, it measures the UV absorption method directly on treated skin.
ISO 23675, the standard SAES Chemicals has chosen to adopt, is fully in vitro SPF validation — it works entirely on PMMA plates, with no need for volunteers at any stage.

While technically more complex, ISO 23675 is the most ethical SPF testing method, offering high repeatability for validating next-generation suncare innovations. It improves consistency and reproducibility, supporting the development of hybrid SPF solutions that meet global demands.

SAES Getters | Solar Test Analyzer utilizzato per la validazione SPF in vitro secondo ISO 23675

What makes ZeoSAES® UV Booster different

ZeoSAES® UV Booster is an inorganic SPF booster based on engineered zeolites.
It delivers measurable improvements in UV protection (+75% SPF, +38% UVA-PF at just 3% dosage) and is tested following the ISO 23675 in vitro protocol — alongside classic in vivo standards.

This means:

Formulators get reliable, measurable SPF claims, validated across multiple recognized methods.
Brands can highlight ethical SPF testing, aligning with modern suncare innovation and clean beauty standards.
Your final non-nano sunscreen formula is more market-ready worldwide, featuring non-nano particles (<10 μm) and full global compliance (EU, US, Korea, Brazil, China).

Why this matters for your formulation

With ZeoSAES® UV Booster, it’s not just about the data — it’s about flexibility and collaboration.
Our lab team can run dedicated tests on your own base, helping you optimize SPF performance while reducing overall filter load, greasiness, and instability.
Whether you’re developing a daily sunscreen, hybrid SPF primer, baby care or sensitive skin SPF, the booster supports light textures and a satin-like, dry finish that both formulators and consumers expect.