Mineral SunCaps™: Overcoming Formulation Challenges

Mineral UV filters have become more popular these days mainly thanks to their natural mineral sources, excellent safety profile, high SPF efficacy, broad spectrum protection and photostability. Yet developing a mineral sunscreen product is a challenging task and not always straightforward, mainly due to the poorly perceived aesthetics, i.e. skin feel and whitening, associated with them.

Tagra's mineral SunCaps™, Cellu TitanCap™ and Cellu ZinoCap™, are transparent and unbreakable micron-size microcapsules in a powder form with 70% payload. They are more attractive to both manufacturers and consumers due to their enhanced transparency on skin, improved skin feel, ease of use and compatibility with other ingredients while maintaining their efficacy.

A W/O formulation containing 20% of Cellu TitanCap™ (equivalent to 14% free TiO2) was developed by Tagra's R&D team and tested for its in-vitro SPF and transparency.

In-Vitro SPF Results

The formulation was tested by the Solarlight SPF290AS equipment at a wavelength range of 290-400nm using a PMMA plate as a substrate.

The incorporation of 20% Cellu TitanCap™ resulted in an in-vitro SPF value of 25; therefore Cellu TitanCap™ is claimed to typically deliver 1.3 SPF units per 1% of capsules.

Whitening/Transparency Test Results

The whitening/transparency of the formulation was evaluated by visual observation on a human hand and confirmed by analytical measurement using an X-Rite VS450 device (% reflection).

Two formulations, one made with free TiO2 and another made with Cellu TitanCap™, were applied on human skin and tested by physical observation for their transparency/whitening.

• Figure 1: Formulating with Cellu TitanCap™ (A) results in a less whitening appearance than free TiO₂ (B).

• Figure 2: X-Rite analysis for % transparency. An empty plate without formulation (C) served as a reference and was analyzed for transparency after being covered with a formulation containing either Cellu TitanCap™ (A) or free TiO₂ (B).

Conclusion

Thanks to Tagra's mineral SunCaps™, developing an efficient mineral sunscreen product is now accessible for all formulators. The microcapsule powder format offers easy incorporation in all stages of formulation. Less white cast effect, and improved aesthetic formulas with great look and feel, can easily be achieved.

For more information on the formulation, please contact info@tagra.com.

Request a sample of the Tagra ingredients in this formula at tagra.com/engine.