Serum Formulation Review

Regarding your proposed AOX + Whitening serum formulation, here is an assessment addressing your questions and the overall formula:

1. Need for Additional Preservative?

Your formula includes 1,2-Hexanediol (3%) and 1,3-Propanediol (20%), both of which can act as preservative boosters and have some antimicrobial properties themselves. The description for 1,2-Hexanediol at 3% indicates it can help control bacteria according to standard tests. However, relying solely on these ingredients for broad-spectrum preservation in a water-containing formula with many diverse components can be risky. A formal challenge test is highly recommended to confirm the formula's ability to withstand microbial contamination over time. To ensure adequate preservation, especially given the water content (30.67%) and the complex mix of ingredients, it would be advisable to include a recognized broad-spectrum preservative system that is compatible with all components and the final pH of your serum.

2. Texture and Stickiness

With 30.67% water, the formula is not extremely low in water, but it contains a significant amount of humectants: 1,3-Propanediol (20%), 1,2-Hexanediol (3%), and Natural Betaine (3%). While 1,3-Propanediol and Natural Betaine are generally considered less sticky than Glycerin, a total humectant concentration of 26% is quite high. This high level of humectants is likely to contribute to a noticeable, potentially viscous or slightly tacky feel on the skin. The final texture will also be influenced by the LipidSoft™ Solve, the oils (Sea Buckthorn Oil, Pomegranate Seed Oil), S-Proteoglycan™, and PEG-40 Hydrogenated Castor Oil. It is difficult to predict the exact texture without testing, but it may feel heavier or tackier than a very light serum.

Overall Formulation Complexity

Your formula is highly complex, incorporating a large number of active ingredients with diverse properties (antioxidant, whitening, skin barrier support, etc.). While combining multiple actives can offer comprehensive benefits, it also presents significant challenges regarding ingredient compatibility, stability, and potential for irritation. Many of the ingredients have specific requirements for solubility, optimal pH range, and temperature sensitivity during manufacturing and storage. For example, Cholesterol requires high heat for dissolution, while several other actives like EGT-Max™, S-Proteoglycan™, Fullerene C60, Lactobacillus Ferment Lysate, Licorice Extract, and Tranexamic Acid are sensitive to heat and/or light. Ferulic Acid also requires a specific solvent not listed in your formula. Attempting to combine all these ingredients while maintaining their stability and efficacy is very difficult and often leads to compromises or degradation of some components.

It is generally recommended to simplify formulations and focus on a smaller number of key active ingredients (typically 2-4) that are known to be compatible and stable together. This approach helps ensure the efficacy and stability of the final product and minimizes potential issues.