Liquid Foundation SPF50 PA++ Formulation Issues

Based on the formula and the issues described, here are answers to your questions:

1. Formula Separation

The separation you observed, with clear water on top after leaving the formula overnight, indicates an issue with the emulsion stability. This type of formula, containing high levels of silicones, oils, water, and pigments, is a complex emulsion (likely water-in-oil or a silicone-based emulsion).

Possible reasons for the separation include:

• Emulsifier System: The formula uses SiliSolve (PEG-10 Dimethicone), which is typically an oil-in-water (O/W) emulsifier, while the mixing method (adding water to oil) is more suited for water-in-oil (W/O) emulsions. This mismatch can lead to instability.
• Mixing Process: While adding the water phase slowly to the oil phase is correct for W/O, the temperature and shear force/time during blending are critical. Insufficient or improper mixing can result in a weak emulsion that separates over time.
• Pigment Dispersion: Pigments (Mica, Titanium Dioxide, Iron Oxides) need to be perfectly dispersed and stabilized within the correct phase (usually the oil/silicone phase in W/O or silicone emulsions). Poor pigment handling can disrupt the emulsion.
• Electrolytes: Magnesium Sulfate is present and can sometimes affect emulsion stability depending on the emulsifier system.

Recommendations to address separation:

• Review Emulsifier: Ensure the emulsifier system is appropriate for the intended emulsion type (W/O or silicone emulsion). Consider using silicone-specific emulsifiers or a blend designed for these systems.
• Optimize Mixing: Follow recommended mixing procedures precisely, especially regarding temperature and blending time. Ensure both oil and water phases are heated appropriately (see point 2 below) and blended with sufficient shear for the recommended duration (e.g., 15 minutes or more) after the addition is complete.
• Improve Pigment Dispersion: Ensure all pigments are fully wetted and dispersed in the oil/silicone phase before emulsification begins.
• Consider Stabilizers: Incorporating a suitable polymeric stabilizer or rheology modifier compatible with your emulsion type can significantly improve long-term stability.

2. SPF Protect Ultra™ II and Heat

Yes, according to the product information for SPF Protect Ultra™ II, it is recommended to use heat for mixing. The description states it is soluble in oil and advises using heat between 70-80 degrees Celsius to melt it and ensure it integrates properly into the formula for full sun protection performance. The sample formulas provided also show heating the oil phase containing SPF Protect Ultra™ II to 70 degrees Celsius.

Therefore, heating the oil phase containing SPF Protect Ultra™ II to the recommended temperature range (70-80°C) and maintaining temperature during the addition of the water phase is crucial for achieving a stable and effective formula.