Addressing White Cast and Stickiness in Sunscreen Formula

Hello, I understand the issues you're facing with the sunscreen formula resulting in a white cast and stickiness. The formula you have uses Oil Free Titanium Dioxide as the main sunscreen ingredient, which is a Physical Sunscreen.

These issues are common with formulas using Physical Sunscreens, especially at high concentrations like 20% in this formula. The texture is also influenced by the gelling agent like Sepiplus 400 and Caprylic/Capric Triglyceride.

Addressing Stickiness

Stickiness can result from the dispersion of Titanium Dioxide and the overall texture of the formula. Adding ingredients that help the product spread easily and provide a lighter feel can help.

• Cyclopentasiloxane: This is a volatile silicone that provides a soft, smooth, non-sticky feel and helps the formula spread better. It can be added to the oil phase of the formula.
• LipidSoft™ D5: This is a Cyclomethicone replacer that offers similar properties, providing a light, slippery feel and improving texture without stickiness.
• Dimethicone (Very Light/3): This is a non-volatile silicone but has very low viscosity, providing a light and smooth coating on the skin for a longer time than Cyclopentasiloxane without feeling sticky.

Slightly reducing the amount of Sepiplus 400 (if the formula stability is maintained) might also help reduce stickiness.

Addressing White Cast

White cast is a characteristic issue of Physical Sunscreens like Titanium Dioxide because it is a white powder that sits on the skin surface to reflect UV radiation.

To reduce white cast while still using Titanium Dioxide, you can choose Transparent Titanium Dioxide types with very small particle sizes (nano-sized) and special surface coatings, such as with Dimethicone or Hydrogen Dimethicone. These coatings help reduce light scattering and minimize the white appearance on the skin.

• Titanium Dioxide Transparent (15nm, Dimethicone Coated): This is an example of a transparent Titanium Dioxide designed for sunscreen formulas that need to be clear and not leave a white cast, while still providing good sun protection.

However, using transparent Titanium Dioxide at high concentrations for high SPF might still leave some feel on the skin, and the sun protection performance might differ slightly from pigmentary types. It's recommended to test the SPF efficacy of the modified formula.

In summary, improving this formula to reduce stickiness and white cast can be achieved by adding ingredients that provide a lighter texture and selecting an appropriate transparent type of Titanium Dioxide.