Sunscreen Formulation Adjustment for W/O Emulsion

Question

I want to formulate a sunscreen using the following mineral filters:

Zinc Oxide Nano EasyDisperse 10%
Titanium Dioxide Nano EasyDisperse 5%

These total 15% mineral filters. I want the final product to be water/sweat resistant, long-lasting, have a light texture, and be easy to spread without forming clumps on the skin. The target SPF is 35 PA+++.

Given these requirements and the chosen mineral filters, I understand I need to change the emulsifiers and increase the oil phase compared to an initial attempt using Light Cream Maker and Water-Capsule. What is a suitable formulation approach, specifically regarding emulsifiers and oil content, to achieve these properties with these mineral filters?

MySkinRecipes Expert · Accepted Answer

Subject: Feedback on Sunscreen Formulation

Regarding your sunscreen formulation and your goal of achieving a water/sweat resistant, long-lasting, light-textured, and easy-to-spread product with SPF 35 PA+++:

Based on the discussion, your initial formula using Light Cream Maker and Water-Capsule as emulsifiers, along with a high concentration of mineral sunscreens (Zinc Oxide and Titanium Dioxide), might face challenges in achieving the desired texture, stability, and water resistance. Mineral sunscreens require specific emulsification systems and sufficient oil phase to disperse well, feel light, spread easily, and provide water resistance.

The revised formula proposed in the conversation is a more suitable approach to meet your requirements. This formula shifts to a Water-in-Oil (W/O) emulsion system, which is generally better for water resistance and handling high mineral loads.

The suggested revised formula includes:

Zinc Oxide Nano EasyDisperse (10%)
Titanium Dioxide Nano EasyDisperse (5%)
LipidSoft CC (7.5%) - Increased amount to help disperse mineral sunscreens and improve spreadability.
LipidSoft Lite (7.5%) - Increased amount for better feel and spreadability.
Water-in-Oil EZ (3%) - A W/O emulsifier suitable for mineral sunscreens.
Oil-Fix (1%) - A stabilizer for W/O emulsions.
1,2-Hexanediol (3%) - Acts as a preservative and humectant.
Water (up to 100%)

This revised formula is designed to address the limitations of the initial one, providing a more stable W/O emulsion, better dispersion of mineral sunscreens, improved feel and spreadability, and enhanced water resistance, while aiming for SPF 35 PA+++.