Anhydrous Sunscreen Formulation with Vitamin C: Solubility and Stability Issues

Based on your proposed formula and the feedback provided, here's an assessment:

1. Can this formula be produced and used? What adjustments are needed?

   • Vitamin C Solubility: The primary challenge is that L-Ascorbic acid ultra-fine is not soluble in your proposed anhydrous silicone/oil base. It will remain as solid particles, leading to a gritty or powdery texture on the skin and potentially poor absorption compared to dissolved Vitamin C.
   • Formula Stability & Texture: Achieving a stable, homogenous, and pleasant texture with a high percentage of dispersed powder (Vitamin C) in a silicone/oil/glycol base is difficult due to compatibility issues between the phases.
   • SPF/PPD Estimation: Ingredients like Bisabolol, Tocopheryl acetate, and Ubiquinone are antioxidants and skin beneficials, but they are not UV filters. They will not significantly boost the SPF or PPD values, which are determined by the actual UV filters and require testing.
   • Adjustments: To incorporate L-Ascorbic acid effectively in an anhydrous formula, you would typically need a solvent compatible with the base, or use a different form of Vitamin C. This requires a fundamental change in the formulation approach.

2. Is the mixing procedure correct?

   • Given the potential incompatibility and solubility issues mentioned above, the proposed mixing procedure is unlikely to yield a stable and homogenous product. You would likely face difficulties in smoothly incorporating all ingredients without separation.

In conclusion, while the concept is interesting, the current formulation is unlikely to be stable, have a desirable texture, or effectively deliver the Vitamin C due to solubility and compatibility issues. Achieving a stable anhydrous silicone sunscreen with dissolved Vitamin C requires a more complex formulation strategy.