Troubleshooting Serum Separation
Question
Seeking advice on a serum formulation that separates into layers despite using different emulsifiers (PEG-40, Tween 20). The formula includes oil and water phases, and the mixing procedure involves adding the water phase to the oil phase. What ingredient or process step is causing this instability?
Answer
Subject: Troubleshooting Serum Separation
Hello,
You're experiencing separation in your serum formulation, which is a common issue when combining oil and water phases. Based on your formula and process, here are some potential reasons and suggestions:
Mixing Procedure: The most likely cause of separation is the way you are combining the phases. For an oil-in-water (O/W) emulsion like a serum, the standard procedure is to slowly add the oil phase (Part C, containing your oils and emulsifier) into the water phase (Part AB) while continuously mixing. Your current method of pouring the water phase into the oil phase is unusual and can lead to instability.
- Suggestion: Try preparing Part AB and Part C separately. Then, while mixing Part AB vigorously (ideally with a high-speed mixer or homogenizer if available, otherwise strong stirring), slowly drizzle Part C into Part AB. Continue mixing until fully emulsified before adding Part D.
Emulsifier System: While Tween 20 is an O/W emulsifier, the high concentration (4%) relative to the small oil phase (total 0.9%) is quite high and might not be optimal for creating a stable, aesthetically pleasing emulsion, although it should theoretically be enough to prevent gross separation if mixed correctly. Sometimes, a single emulsifier isn't sufficient, or a co-emulsifier is needed to improve stability.
- Suggestion: If changing the mixing procedure doesn't fully resolve the issue, you might need to experiment with a different emulsifier or add a co-emulsifier. However, address the mixing procedure first as it's the more probable cause here.
Ingredient Compatibility/Quality: Less likely to cause immediate separation, but the specific form of ingredients like "Squalane Oil Gel" or the quality of oils/Retinol could potentially play a minor role in long-term stability.
In summary: The primary factor contributing to the separation is most likely your mixing method. Please try the suggested method of slowly adding the oil phase (Part C) to the water phase (Part AB) with vigorous mixing.
I hope this helps you troubleshoot your formulation!