Choosing Zinc Oxide for a Formula with Avobenzone and Titanium Dioxide

When formulating a sunscreen that includes both Avobenzone (a chemical filter) and mineral filters like Zinc Oxide and Titanium Dioxide, compatibility is key to ensuring stability and effectiveness. Avobenzone can be prone to degradation, especially in the presence of uncoated mineral oxides.

You are asking about which Zinc Oxide to use in a formula with Avobenzone and Titanium Dioxide 15nm Liquid (Gloss), specifically comparing Zinc Oxide Neutral Coated and Zinc Oxide 35nm Liquid for dispersion, lack of white cast, and compatibility.

Based on the product information:

• Avobenzone: While Avobenzone can be sensitive to mineral filters, certain coated or specifically treated mineral dispersions are designed to be compatible.
• Titanium Dioxide 15nm Liquid (Gloss): The description for this product indicates it can be used with formulations containing Avobenzone, stating that its uncoated nature does not pose a problem for Avobenzone stability. This is a specific compatibility claim for this particular Titanium Dioxide product.
• Zinc Oxide 35nm Liquid: This is a liquid dispersion of 35nm nano Zinc Oxide, known for providing good broad-spectrum protection with minimal white cast and being easy to incorporate. Its description recommends using it with Titanium Dioxide 15nm Liquid. However, it does not explicitly mention compatibility with Avobenzone.
• Zinc Oxide Transparent Dispersion (C12-15 alkyl benzoate Base) and Zinc Oxide Transparent Dispersion (Isopropyl Palmitate Base): These products are coated nano Zinc Oxide dispersions. Coatings, such as Triethoxycaprylylsilane found in these products, are typically applied to improve dispersion, reduce reactivity, and enhance compatibility with other ingredients, including potentially sensitive organic filters like Avobenzone. They are designed for transparent, low-white-cast formulations and are suitable for use with chemical sunscreens.

Considering the need for compatibility with Avobenzone to maintain its stability, a coated Zinc Oxide is generally the preferred choice. The coated Zinc Oxide Transparent Dispersions (in either C12-15 alkyl benzoate or Isopropyl Palmitate base) are specifically designed with a coating that helps mitigate the potential for Avobenzone degradation and are suitable for transparent sunscreen formulations with low white cast.

While Zinc Oxide 35nm Liquid is an excellent option for low white cast and ease of use and is recommended for use with the compatible Titanium Dioxide 15nm Liquid, the coated Zinc Oxide Transparent Dispersions offer a specific advantage in terms of enhancing stability when used alongside Avobenzone due to their protective coating.

Therefore, for a formula containing Avobenzone and Titanium Dioxide 15nm Liquid (Gloss), the Zinc Oxide Transparent Dispersion (C12-15 alkyl benzoate Base) or Zinc Oxide Transparent Dispersion (Isopropyl Palmitate Base) would likely be better choices due to their coating which promotes compatibility and stability with Avobenzone, while still providing excellent dispersion and minimal white cast.