Body Oil Formulation: Emulsification and Preservative Issues
Question
I'm trying to create a body oil with the following ingredients, aiming for a preservative-free formula:
- Sesame Oil 70%
- Tocopheryl Acetate (Vitamin E Acetate) 1%
- Vitamin C Ester (Ascorbyl Palmitate) 1%
- Niacinamide (Vitamin B3) 10%
- N-Acetyl-D Glucosamine 10%
- Polysorbate 20 (Tween 20) 2%
- Water (DI) 8%
When mixing, the formula separates into layers. I understand Polysorbate 20 is used as an emulsifier, but it doesn't seem to work for this formula. I also wanted to avoid using a preservative.
Could you please explain why the formula is separating and how I can achieve a stable product with these ingredients? Is it possible to include the water-soluble ingredients without a preservative in a stable body oil format?
Answer
Feedback on Your Body Oil Formula
Based on your formula and the staff's feedback, your current mixture is unlikely to emulsify well with only 2% Polysorbate (Tween 20).
Here's why and how you might adjust it:
The Problem: Polysorbate (Tween 20) is a relatively weak emulsifier, primarily used for oil-in-water (O/W) emulsions where the oil phase is small. Your formula has a very high oil content (70% sesame oil) and a low water content (8%). This ratio and the type/amount of emulsifier are not suitable for creating a stable emulsion; the oil and water phases will likely separate.
Possible Adjustments (Aligning with Staff Advice): You have two main paths depending on the type of product you want:
- Option A: Make it a Pure Body Oil: If your primary goal is a body oil, the simplest approach is to remove the water, Niacinamide, and N-Acetyl-D Glucosamine. The remaining ingredients (Sesame Oil, Tocopheryl Acetate, Vitamin C Ester) are all oil-soluble and will mix together perfectly without needing an emulsifier. This creates a stable oil blend and eliminates the need for a preservative.
- Option B: Make it an Emulsion (Cream/Lotion): If you specifically need to include the water-soluble ingredients (Niacinamide, N-Acetyl-D Glucosamine), you must formulate it as an emulsion (like a cream or lotion). This requires a different, more robust emulsifier system capable of handling a high oil load, as suggested by the staff (e.g., Soy Lecithin or LotionBliss + Cetyl Alcohol). Importantly, any product containing water must also include a preservative to prevent microbial growth, even if you initially preferred no preservative. This option changes the product type significantly from an oil to an emulsion.
In summary, the current formula as written will likely separate. You need to decide whether you want a pure oil blend (remove water and water-solubles) or an emulsion (add proper emulsifier and preservative, changes product type).