Formula Analysis: Texture and Stability

You've provided a complex formula with a high concentration of active ingredients and humectants, using Moist Cream Maker, Xanthan Gum (smooth texture), and Sodium Stearoyl Glutamate as the emulsifier and stabilization system.

Texture (Stickiness)

Your formula contains several ingredients known for their moisturizing properties, which can contribute to a sticky or tacky feel, especially at higher concentrations. These include:

• Glycerin (3%)
• Propanediol (5%)
• Natural Moisturizing Amino Acids (5%)
• TransMoist™ (2%)
• 1,2-Hexanediol (3%)

The total percentage of these humectants is quite high (18%). While they provide excellent hydration, this level is likely to result in a noticeable sticky or tacky feel on the skin after application.

Additionally, the high concentration of various active ingredients dissolved in the water phase can also increase the overall tackiness of the serum. The Xanthan Gum, even the "smooth texture" type, can still contribute slightly to a sticky or "draggy" feel depending on the overall formula composition.

• To reduce stickiness:*
• Consider slightly lowering the percentage of some humectants, such as Glycerin, Propanediol, or Natural Moisturizing Amino Acids.
• Ensure you are using LipidSoft™ Dry II (Dicaprylyl Carbonate) at the specified 8%, as this emollient is designed to provide a dry, non-greasy feel which helps counteract the tackiness from humectants and thickeners. You could potentially explore slightly increasing this or adding other dry-feel emollients if compatibility allows.

Stability

You mentioned that a previous formula using Moist Cream Maker 3% + standard Xanthan Gum 0.5% separated. In your current formula, you've changed the Xanthan Gum type to the "smooth texture" version and added Sodium Stearoyl Glutamate at 0.25%.

• Improved Emulsification/Stabilization: The addition of Sodium Stearoyl Glutamate is a good strategy to improve stability. Sodium Stearoyl Glutamate is a powerful co-emulsifier that works well with fatty alcohols (like those in Moist Cream Maker) and is often used to stabilize challenging formulas, especially those with electrolytes (which your formula has in the form of various active ingredient salts). Moist Cream Maker's description also suggests using Xanthan Gum to improve stability in formulas containing electrolytes.
• Xanthan Gum Type: Using the "smooth texture" Xanthan Gum might offer better compatibility or a more stable viscosity profile compared to the standard type, which could have been a factor in the previous separation.
• High Active Load: While the updated emulsifier system is stronger, your formula contains a very high concentration of diverse active ingredients (over 30% excluding the base components like water, emulsifiers, emollients, humectants, and preservative). High concentrations of active ingredients, particularly those that are salts or affect pH, can significantly challenge the stability of an emulsion over time.

The current formula is likely more stable than your previous attempt due to the inclusion of Sodium Stearoyl Glutamate and potentially the different Xanthan Gum type. However, with such a complex mix and high active load, there is still a risk of long-term instability (like viscosity loss or separation) under various storage conditions.

• To improve stability:*
• Ensure the manufacturing process involves heating the oil phase (containing Moist Cream Maker, Sodium Stearoyl Glutamate, Sea Buckthorn Oil, LipidSoft™ Dry II, MSH White™, and Phospholipid) and the water phase separately to the required temperature (around 80-90°C for Moist Cream Maker and Sodium Stearoyl Glutamate), then slowly adding the oil phase to the water phase while blending thoroughly at high speed to form the emulsion. Water-soluble ingredients like Xanthan Gum, humectants, and active ingredients should be added to the water phase at appropriate steps (Xanthan Gum dispersed first, then dissolved in water phase; heat-sensitive actives added during cooling).
• Verify and maintain the optimal pH range for the formula. Many of your active ingredients and emulsifiers work best within a specific pH range (e.g., Moist Cream Maker and Xanthan Gum are quite flexible, but actives like Tranexamic Acid and Safe-B3™ prefer a pH between 3-8, ideally 4-7). Significant deviations or changes in pH over time may impact stability.
• Perform rigorous stability testing, including accelerated tests like oven aging (e.g., 45°C) and freeze-thaw cycles, to assess the long-term stability of the formula before mass production.