Formulation Advice for Water-in-Oil Serum

Regarding your questions about modifying the Water-in-Oil serum formulation:

1. Adding LipidSoft F (Ethyl Linoleate)

Yes, you can add LipidSoft F (Ethyl Linoleate) to this formulation. LipidSoft F is an emollient that helps balance skin moisture, reduce excess sebum, and restore the skin barrier, which can be beneficial even for dry skin by improving overall skin health and texture.

You can add LipidSoft F to the oil phase of your formula. A suitable starting percentage would be 5-10%. When adding LipidSoft F, you may need to slightly reduce the percentage of other oils in the formula, such as Mineral Oil or Squalane, to maintain the overall balance of the oil phase and ensure the emulsion remains stable.

LipidSoft F has a light texture and can improve the feel of the serum. It should be mixed into the oil phase and can withstand heat up to 80°C for a short period (not more than 15 minutes).

2. Suitable Preservative

The formula already uses Mild Preserved Eco at 1%, which is a suitable preservative for this type of cosmetic formulation. Mild Preserved Eco is gentle, considered preservative-free by FDA regulations, and also acts as a humectant. The recommended usage rate for Mild Preserved Eco in general cosmetic formulas is 1.0-1.5%, so your current usage of 1% is appropriate.

Other suitable preservative options you could consider include:

• Mild Preserved SC10: Also preservative-free by FDA definition, gentle, and effective. Recommended usage is 1.0-1.5%.
• Mild Preserved CGZ: Another gentle, preservative-free option with a wide pH range suitability. Recommended usage is 1.0-1.5%.
• Mild Preserved COS: A broad-spectrum preservative effective in a pH range of 2-8. Recommended usage is 0.75-1.5%.

When choosing a preservative, ensure it is compatible with the other ingredients and the pH of your final formulation. Always perform a challenge test to confirm the effectiveness of the chosen preservative in your specific formula.