Proper Dispersion of Silica Dimethyl Silylate in Oil for Lip Gloss

It's great that you are working on perfecting your lip gloss formula! Dealing with the dispersion of ingredients like Silica Dimethyl Silylate is a common challenge, especially to achieve a smooth, lump-free texture and minimize air bubbles.

Based on your situation and the properties of Silica Dimethyl Silylate (such as the Oil-Fix™ series), here's a refined approach using your overhead stirrer:

Recommended Stirrer Blade

For effectively dispersing Silica Dimethyl Silylate in oil, a saw-tooth or dispersion blade is highly recommended over a propeller blade. Here's why:

• Propeller blades are good for general mixing and creating flow, but they provide relatively low shear.
• Saw-tooth/Dispersion blades are specifically designed to impart high shear, particularly at the blade tips. This high shear is crucial for breaking down the agglomerates (clumps) of Silica Dimethyl Silylate powder and ensuring the particles are properly wetted and dispersed throughout the oil phase. This leads to a smoother, more uniform gel structure.

While rotor-stator homogenizers provide even higher shear, an overhead stirrer with a saw-tooth blade, used correctly, can often achieve sufficient dispersion for formulations like lip gloss, as suggested by some example formulations.

Dispersion Technique with Overhead Stirrer

Follow these steps when using your overhead stirrer with a saw-tooth blade:

1. Prepare the Oil Phase: Ensure your oil phase is ready. Slightly warming the oil (if compatible with your formula) can sometimes help reduce viscosity and improve initial wetting, but avoid excessive heat.
2. Start Stirring: Position the saw-tooth blade correctly (usually about one blade diameter off the bottom) and start stirring the oil at a moderate speed. Aim for a vortex that pulls the surface liquid down towards the blade, but avoid a vortex so deep it pulls air in excessively.
3. Add Silica Dimethyl Silylate Slowly: Gradually add the Silica Dimethyl Silylate powder into the vortex. Adding it slowly allows the powder to be immediately drawn into the high-shear zone of the blade and wetted by the oil, preventing large clumps from forming.
4. Increase Speed (Carefully): Once all the powder is added, you may need to increase the stirring speed to provide sufficient shear for complete dispersion. The goal is to break down any remaining small agglomerates. Observe the mixture – it should start to thicken and become more uniform. Be mindful of introducing excessive air at higher speeds.
5. Mix for Sufficient Time: This is critical. Silica Dimethyl Silylate requires adequate time under shear to fully swell and build viscosity, and for all particles to disperse. Based on typical usage instructions for similar ingredients, mixing for at least 10-15 minutes after adding the powder is often necessary for complete dispersion and gel formation. Continue mixing until the mixture appears smooth and homogenous with no visible powder particles or clumps.
6. Address Air Bubbles: High-shear mixing can introduce air. After the dispersion is complete and the desired texture is achieved, reduce the stirring speed significantly. Stir slowly for a period to allow trapped air bubbles to rise and escape. Gentle warming can also help reduce viscosity temporarily, allowing bubbles to escape more easily. The Oil-Fix™ types of Silica Dimethyl Silylate are also noted to help reduce foam formation at concentrations above 0.5%, which should be beneficial at your 1% usage level.

Using the correct blade and allowing sufficient mixing time under appropriate shear are key to successfully dispersing Silica Dimethyl Silylate and achieving a smooth, lump-free lip gloss with minimal persistent air bubbles. These types of Silica Dimethyl Silylate are excellent for thickening oils, providing suspension for pigments like D&C colors, and improving the texture of lip products.

Good luck with your next batch!