Sunscreen Formulation: Waterproof, Lightweight, and Ensulizole Solubility

Hello,

Thank you for your questions regarding your sunscreen formulation.

Regarding your first question about SPF Protect Ultra, the staff has clarified that while the old version could be used without heat, heating the new version (and likely the old batch as well, for consistency) helps it incorporate more easily into the formula. The core function should be similar.

Regarding your note about Light Cream Maker not being suitable for high oil content, the staff explained that while it worked in your previous formula, newer emulsifiers like Milk Lotion Maker (though not waterproof) or Water-in-Oil EZ (waterproof, higher oil capacity) might be better options depending on the specific formula requirements and desired properties. However, since your goal is a waterproof formula, Light Cream Maker was acceptable, and the proposed new formula uses different emulsifiers.

Now, addressing your proposed new formula (Formula 2) and questions:

Proposed Formula 2:

1. SPF Protect Ultra 20%
2. LipidSoft™ Lite 6%
3. Water-Capsule 3%
4. Satin Mousse 2%
5. Ensulizole 4%
6. Disodium EDTA 0.2%
7. Distilled Water 61%
8. Phenoxyethanol 0.8%
9. AminoSilk 3%

This formula is viable for creating a waterproof, lightweight, non-greasy sunscreen that is not too liquidy, as you described.

Regarding Ensulizole and pH: The staff correctly pointed out that Ensulizole needs a pH range of 6.8-7.0 to dissolve properly. If it doesn't dissolve, it won't provide sun protection. Disodium EDTA at 0.2% is unlikely to significantly lower the pH, but to ensure Ensulizole dissolves, you should add both Ensulizole and Disodium EDTA to the water phase (Part B) first. Then, check if the Ensulizole is fully dissolved. If not, you will need to measure the pH and adjust it using a suitable acid or base (like Triethanolamine or Citric Acid solution) until the pH is between 6.8-7.0 and the Ensulizole dissolves completely. Important: Do not add other water-soluble ingredients (like Phenoxyethanol) to the water phase after adjusting the pH for Ensulizole, as this could change the pH and cause the Ensulizole to precipitate.

Proposed Mixing Method for Formula 2: Your proposed method is correct, with the crucial addition of the pH adjustment step for the water phase:

1. Mix Part A (SPF Protect Ultra, LipidSoft™ Lite, Water-Capsule). Heat to 70°C and stir to dissolve/combine.
2. Mix Part B (Satin Mousse, Ensulizole, Disodium EDTA, Distilled Water). Before heating, ensure Ensulizole is dissolved by adjusting the pH to 6.8-7.0 if necessary. Then, heat Part B to 70°C and stir.
3. Add Part A to Part B all at once. Stir slowly at low speed until emulsified. Continue stirring while cooling.
4. When the temperature drops below 50°C, add Phenoxyethanol and AminoSilk. Stir until fully incorporated.

Regarding adding Milk Lotion Maker: The staff previously explained that Milk Lotion Maker is not waterproof. Since your primary goal is a waterproof sunscreen, adding Milk Lotion Maker would not be suitable for this purpose. The combination of Water-Capsule and Satin Mousse in your proposed formula is appropriate for achieving water resistance with the given oil content. If you needed to incorporate significantly more oil (e.g., for a much higher SPF), a different emulsifier system like Water-in-Oil EZ (which is waterproof and supports up to 35% oil) might be considered, as the staff mentioned.

In summary, your proposed Formula 2 is suitable for a waterproof, lightweight sunscreen. The key is to ensure the Ensulizole is properly dissolved in the water phase by adjusting the pH to 6.8-7.0 before combining the phases for emulsification.

Thank you.