Sunscreen performance depends on maintaining balanced UVA and UVB coverage within a uniform, stable film during use.
UVA and UVB are not the same
SPF mainly relates to protection against UVB-induced erythema, while UVA protection requires specific criteria and methods. A sound project defines the target market, protection level, format and claims from the briefing stage.
What photostability means
Photostability describes the system’s ability to maintain performance under radiation. It does not depend only on each filter in isolation: combinations, solvents, antioxidants, dispersants, oil phase and vehicle also matter. The architecture must comply with the rules of the destination market.
The film on skin is part of the system
Emulsion, rheology, film formers and application method affect product distribution. A formula that is difficult to spread or leaves discontinuous areas can impair uniformity. Sensory design therefore affects real-world application and reapplication.
From prediction to testing
Calculation tools and pre-screening can help compare prototypes and reduce iterations, but they do not replace validation of the final formula. SPF, UVA or water-resistance claims must be supported by the methods and evidence required in the target market.
Controls before manufacturing
- Physical and chemical stability.
- Filter distribution and homogeneity.
- Compatibility with packaging and dispensing system.
- Definition of the testing and claims plan.
- Pilot batch and confirmation of critical process parameters.
OKT GLOBAL coordinates formulation, quality, regulatory work, applicable external testing, pilot batches and manufacturing in Spain under ISO 22716.