Review of Water-Resistant, Lightweight Sunscreen Formula

Subject: Review of Sunscreen Formula

Thank you for submitting your sunscreen formula for review. This formula appears to be designed as a water-in-oil (W/O) emulsion, aiming for a lightweight, water-resistant texture.

Here is a review of the percentages and some suggestions:

• Sunscreen Actives: The total of 20% Titanium Dioxide and Zinc Oxide is a good level for achieving high SPF protection.
• Silicones: The high percentage of silicones (Silicone Gel, Cyclotetrasiloxane, Dimethicone, Silicone Blender) totaling 43% will contribute significantly to the desired lightweight, non-greasy feel and water resistance. Please note that Cyclotetrasiloxane (D4), if product 6850 is indeed D4, has potential regulatory concerns in some regions. You might consider replacing it with Cyclopentasiloxane (product 171) or reducing its amount.
• Texture Enhancers: PMMA Booster, QuikBlur, and BB Micro Silk (total 13%) are good additions for improving texture, providing soft focus, and absorbing oil.
• Emulsifier & Water: This is the main area for concern. The percentage of Warp Cream Maker (emulsifier) at 15% is very high for a W/O system. Typical usage is much lower (e.g., 5-8%). Consequently, the percentage of Water at 7.7% is very low for the internal phase of a W/O emulsion, which usually has 30-60% water. This imbalance (high emulsifier, low water) could lead to instability (phase separation) or a poor, potentially waxy or oily texture that is difficult to spread, rather than a lightweight feel.

Suggestions for Adjustment:

• It is highly recommended to reduce the percentage of Warp Cream Maker (e.g., to 5-8%) and increase the percentage of Water accordingly (e.g., to 30-40%). This will create a more stable and typical W/O emulsion structure.
• Adjust the percentages of silicones and other oil-soluble ingredients within the remaining oil phase percentage based on your desired sensory feel and cost considerations.
• Review the use of Cyclotetrasiloxane (product 6850) and consider replacing it with Cyclopentasiloxane (product 171) or reducing its amount if regulatory compliance is a concern.

Mixing Instructions (General for W/O Emulsion):

1. Oil Phase: Combine all oil-soluble ingredients (Titanium Dioxide Liquid, Zinc Oxide Liquid, Silicone Gel, Cyclotetrasiloxane, Dimethicone, PMMA Booster, Silicone Blender, Warp Cream Maker, Beige Iron Oxides EasyMix™, QuikBlur™, BB Micro Silk™). Mix well to ensure all components, especially powders and dispersions, are evenly distributed.
2. Water Phase: Combine Water and Mild Preserved Eco™. Mix until homogeneous.
3. Emulsification: Slowly add the Water Phase to the Oil Phase while mixing continuously with a high-shear mixer (e.g., homogenizer). High shear is crucial for forming a stable W/O emulsion. Add the water phase gradually, especially at the beginning.
4. Post-Emulsification: Continue mixing at a moderate speed until the emulsion is uniform and stable.

Regarding Heat:

• Heating is not strictly necessary for this specific formula as most ingredients are liquids or dispersions.
• However, gently warming the Oil Phase (e.g., to 40-50°C) might help ensure the emulsifier and any solid powders are better dispersed before adding the water phase. The Water Phase can be added at room temperature or slightly warmed.
• The key factor for successful W/O emulsification is using high-shear mixing during the addition of the water phase, more so than applying heat.

We hope this review is helpful!