Foam formation in cosmetic gel formulation

Foam formation in your formulation after sitting for a while is a common issue and is likely due to a combination of the ingredients used and the mixing method.

Here's a breakdown of why this might be happening:

• Air Incorporation during Mixing: The blending step, especially when combining the two phases, can whip air into the mixture. The more vigorously you blend, the more air is likely to be incorporated.
• Role of Surfactants: Your formula contains Polysorbate 20 (Tween 20), which is a surfactant. Surfactants reduce the surface tension of liquids, making it easier for air bubbles to form and stabilize within the product.
• Role of Thickeners/Gelling Agents: Ingredients like Carbomer and Snail Resin act as thickeners and gelling agents. They increase the viscosity of the formulation, which helps to trap the incorporated air bubbles and prevent them from rising to the surface and dissipating quickly. This leads to the foam becoming visible and stable over time.

Essentially, the blending process introduces air, and the combination of the surfactant (Tween 20) and the thickeners (Carbomer, Snail Resin) stabilizes this air, causing the foam to appear and persist.

To minimize foaming in your future batches, you could try:

• Mixing the ingredients more slowly or gently.
• Using a mixing method that introduces less air, such as stirring with a paddle instead of high-speed blending, especially after combining the phases.
• Allowing the mixture to sit for a period after mixing to allow trapped air to escape before packaging.