Sunscreen Formula Review and Feedback

Thank you for sharing your sunscreen formula and questions. Creating a stable and effective sunscreen can be challenging, especially when combining multiple UV filters and active ingredients.

Let's review your formula and address your specific questions:

Formula Composition

Your formula includes a high concentration of UV filters (Zinc Oxide, DHHB, OMC, Octocrylene, Oxybenzone) along with emollients (LipidSoft dry, Cyclomethicone), an emulsifier (Luxury Cream Maker), antioxidants (Hi-EGCG, White Cumin), a preservative (Phenoxyethanol), and a chelating agent (EDTA).

Texture (Sticky, Oily, White Cast)

With a total of 43% chemical and physical UV filters, the formula has a very high solid/oil phase load. While LipidSoft C1215 (LipidSoft Dry) and Cyclomethicone are included to improve feel and spreadability, the high concentration of sunscreens, particularly 10% Zinc Oxide, and the type of emulsifier used (Luxury Cream Maker is recommended for up to 20% oil) are likely to result in a texture that feels heavy, potentially sticky or oily, and may leave a noticeable white cast on the skin. Achieving a light, non-oily, and non-whitening texture with this combination and percentage of ingredients is difficult.

Water and Sweat Resistance

Your formula uses Luxury Cream Maker, which typically forms an oil-in-water (O/W) emulsion. O/W emulsions generally provide minimal to no water or sweat resistance. For better water resistance, a water-in-oil (W/O) emulsion system or specific water-resistant film formers would be needed.

Color from Hi-EGCG

Hi-EGCG is a dark green-brown liquid extract. At 2.5%, it will likely impart a noticeable color to the cream itself, potentially giving it a greenish or brownish tint. However, this color will not make your skin tone darker when applied. It only affects the appearance of the product.

Mixing Method and Stability

The proposed mixing method is quite simple for a complex sunscreen emulsion. Properly dispersing 10% Zinc Oxide, even the EasyDisperse type, usually requires more robust mixing, potentially including a homogenizer, to ensure even distribution and prevent settling or instability. The high oil/silicone phase content also exceeds the typical capacity of Luxury Cream Maker, making formula separation highly probable.

Incorporating high percentages of water-soluble extracts like Hi-EGCG and White Cumin into an emulsion with a large oil phase can further challenge stability.

Recommendations

To improve the texture and stability, you might consider:

• Simplifying the formula: Reduce the total percentage of UV filters or select filters that contribute less to heaviness and white cast.
• Adjusting Emulsifier: Consider an emulsifier designed for higher oil loads or a water-in-oil emulsifier for better water resistance and potentially a different feel. Satin Cream Maker was mentioned as another option, but it also has an oil limit (25%).
• Optimizing Zinc Oxide Dispersion: Ensure thorough dispersion of Zinc Oxide using appropriate techniques and potentially additional dispersing agents.
• Reducing Extracts: Consider using Hi-EGCG and White Cumin at lower concentrations if their primary purpose is antioxidant benefit, as high percentages can impact formula stability and texture.

Creating a stable, effective, and cosmetically elegant sunscreen requires careful formulation and testing. It's often recommended to start with simpler formulas or base formulations designed for stability.

I hope this detailed feedback helps you refine your sunscreen formulation!