Formula Separation in Water-in-Oil Sunscreen Emulsion

Asked by: jn_andy On: March 08, 2019 Product Type: Cosmetics

Question

I have a formula with the following ingredients and percentages:

  • Water: 53.9%
  • Sodium PCA: 1%
  • LipidSoft CC: 9%
  • Titanium Dioxide Easy Dis: 1%
  • Zinc Oxide nano: 5%
  • SPF Protect Ultra II: 12%
  • Water in Oil EZ: 2.5%
  • Isododecane: 6%
  • Cyclomethicone: 3%
  • Aloe Vera Extract: 1%
  • Phenoxyethanol SA: 0.5%
  • Vitamin E (Tocopheryl Acetate): 0.1%
  • Oil Fix: 1%
  • Polymethylsilsesquioxane: 4%

The formula separates when left standing. Can I use "silicone plus" to help emulsify it? Also, I didn't see "Oil Fix" on the website; is it discontinued? Can I just use "silicone plus" instead?

Answer

Formula Stability Issue

Your formula is a water-in-oil emulsion, which can be prone to separation if not properly stabilized. The separation you are experiencing is likely due to the instability of this emulsion system, possibly exacerbated by the relatively high proportion of the oil and silicone phase.

Regarding your questions:

  • Silicone Plus: Adding a general "silicone plus" product may not effectively solve the separation issue. Water-in-oil emulsions require specific emulsifiers and stabilizers designed to keep the water and oil phases combined.
  • Oil Fix: Based on our product search, Oil-Fix™ W (Silica Dimethyl Silylate) is available. This ingredient is specifically designed to increase the stability of water-in-oil and water-in-silicone formulas and can help prevent separation, especially in formulas with high oil/silicone content like yours. It also acts as an oil thickener and helps disperse pigments.

To improve the stability of your formula, we recommend the following:

  1. Check your mixing procedure: Ensure you are slowly adding the water phase to the oil phase while continuously blending or stirring vigorously. Incorrect mixing is a common cause of separation in water-in-oil emulsions.
  2. Consider adding Magnesium Sulfate: As suggested in the description for Water-in-Oil EZ, adding 1% Magnesium Sulfate to the water phase before combining with the oil phase can help increase the stability of the water-in-oil emulsion.
  3. Ensure Oil Fix is properly dispersed: If you are using Oil Fix, make sure it is fully dispersed in the oil/silicone phase before adding the water phase. Blend thoroughly.
  4. Review the oil/silicone ratio: Your formula has a significant oil/silicone content, which can make stabilization more challenging. While adjusting the ratio might require reformulating, ensuring proper emulsification and stabilization is crucial for the current composition.

Using Oil Fix (Oil-Fix™ W) as intended in the original formula is important for stability. Simply replacing it with a general silicone product is unlikely to provide the same stabilizing effect.