Formulating Gel Sunscreen with Physical Filters: Addressing White Cast and Dispersion

Question

I am trying to formulate a gel sunscreen with SPF 50++++ and aloe vera for use on both face and body. I am using physical sunscreens like Titanium Dioxide and Zinc Oxide, along with Cyclomethicone. However, I'm facing issues with significant white cast from the high percentage of Titanium Dioxide and poor dispersion of the physical filters due to low Cyclomethicone. Could you provide a revised formula using these ingredients that addresses these problems and helps achieve the desired SPF/PA level?

MySkinRecipes Expert · Accepted Answer

Regarding your question about formulating a gel sunscreen with SPF 50++++ and aloe vera for face and body use, and following up on the previous discussion and staff feedback:

The staff correctly pointed out two main issues with your proposed formula:

The high percentage of Titanium Dioxide (25%) would likely result in a significant white cast, making it less suitable for daily use.
The low percentage of Cyclomethicone (1%) is insufficient to properly disperse the high load of physical sunscreens (Zinc Oxide and Titanium Dioxide), which is crucial for achieving effective and even protection.

Based on this feedback and your goal of creating a gel sunscreen with aloe vera and high SPF/PA, here is a revised formula proposal using the ingredients you mentioned:

Water: 64.3%
Pro Polymer™ (Gel Maker): 2%
Aloe Vera Extract: 1%
Zinc Oxide 200nm EasyDisperse™: 15%
Titanium Dioxide Nano EasyDisperse™: 5%
Cyclomethicone / Cyclopentasiloxane (Low-Odor): 12%
Disodium EDTA: 0.2%
Phenoxyethanol: 0.5%

Explanation of Adjustments:

Reduced Titanium Dioxide: Lowering Titanium Dioxide from 25% to 5% helps significantly reduce the white cast, making the sunscreen more aesthetically pleasing for daily use on the face and body.
Increased Cyclomethicone: Increasing Cyclomethicone from 1% to 12% provides a sufficient amount (12% is 60% of the total 20% physical filters, falling within the staff's recommended 50-70% range) to effectively disperse the Zinc Oxide and Titanium Dioxide particles. Proper dispersion is essential for achieving uniform coverage and maximizing the sun protection factor.

This formula aims to provide a gel texture with the inclusion of aloe vera, offering broad-spectrum protection.

Important Note: Achieving a specific SPF (like SPF 50+) and PA rating requires precise formulation techniques and laboratory testing to confirm the final protection level. This proposed formula is a starting point based on the ingredients and feedback discussed.