Adding Zinc Oxide and Titanium Dioxide to Your Lotion

Based on your lotion formula containing oil, water, e-wax, stearic acid, IPM, and silicone, you can successfully incorporate zinc oxide and titanium dioxide for sun protection. These are mineral powders that need to be properly dispersed in the oil or silicone phase of your formula.

Here's how you can add them:

1. Choose the Right Product: Zinc oxide and titanium dioxide are available as fine powders or pre-dispersions in oils or silicones. Pre-dispersions (like Zinc Oxide Transparent Dispersion in Isopropyl Palmitate or Titanium Dioxide Transparent in Cyclopentasiloxane) are generally easier to use as the particles are already well-separated.

2. Prepare the Dispersion: Whether you use powders or dispersions, you need to mix them thoroughly with a suitable oil or silicone from your formula before adding them to the main lotion base. Based on your ingredients, Isopropyl Palmitate (IPM) or the silicone oil are excellent choices for dispersing these UV filters.

   • Take a small portion of your IPM or silicone (or a blend of your oils/silicones). The exact amount needed for dispersion depends on the concentration of the powders/dispersions you are using and the total batch size.
   • Gradually add the zinc oxide and titanium dioxide powders or dispersions to this oil/silicone portion.
   • Mix using a high-shear method (like a homogenizer, high-speed stirrer, or even a mortar and pestle for small batches followed by vigorous stirring) until the powders are completely wetted and evenly dispersed without any visible clumps or grittiness. Proper dispersion is crucial for effectiveness and texture.

3. Incorporate into the Lotion: Make your lotion emulsion as usual by combining your heated oil phase (oil, e-wax, stearic acid) and heated water phase, and emulsifying them. After the emulsion has formed and cooled down slightly (e.g., to around 40-50°C), but while it is still liquid enough to mix easily, add the prepared dispersion of zinc oxide and titanium dioxide. Continue mixing well until the dispersion is fully incorporated and the lotion is smooth and uniform.

4. Quantity: The amount of zinc oxide and titanium dioxide needed depends on the desired SPF level. As a general guide, achieving SPF 15 typically requires a combined total of 10-15% of these active ingredients, while higher SPFs require more. Always refer to the usage rate recommended by your supplier for the specific grade of zinc oxide and titanium dioxide you are using, as particle size and coating significantly impact performance.

Using both zinc oxide and titanium dioxide is recommended as they provide protection across different ranges of UV radiation (UVA and UVB), offering broad-spectrum protection.