Subject: Sunscreen Separation Issue

Regarding the separation issue you encountered with your SPF15 sunscreen formulation:

Separation in cosmetic emulsions, like sunscreen, can occur due to various factors, including the compatibility of ingredients, the ratio of oil/silicone phase to water phase, and the effectiveness of emulsifiers or dispersants used.

The staff has provided a revised formula which aims to improve the stability of the sunscreen. Key adjustments in the revised formula include:

• Removing Dimethicone and Cyclomethicone.
• Adjusting the percentages of Silicone Gel and SiliSolve.
• Significantly increasing the water content.
• Specifying the use of nano-sized Zinc Oxide and Titanium Dioxide.

These changes are intended to create a more stable emulsion by balancing the phases and using specific ingredients known to work well together in this type of formulation. The staff also noted that the source of Cyclomethicone could potentially affect stability.

Regarding the white cast issue:
Using nano-sized particles for mineral sunscreens like Zinc Oxide and Titanium Dioxide is a common method to reduce or eliminate the white cast often seen with larger particles. The revised formula provided by the staff includes Zinc Oxide 200nm EasyDisperse™ and Titanium Dioxide Nano EasyDisperse™, which are nano-sized versions designed to minimize white cast and improve dispersion. Switching your regular Zinc Oxide to a nano version, as suggested in the revised formula, should help address this problem.