Troubleshooting Skinceuticals C E Ferulic Type Formulation

Regarding the issues you encountered while making the Skinceuticals C E Ferulic type formula, specifically with Ferulic Acid solubility, cloudiness, and pH control, here is an explanation and suggested approach:

Ferulic Acid Solubility and Cloudiness Issues

• Explanation: Ferulic Acid does not dissolve well in plain water but dissolves well in oil-like solvents such as Ethoxydiglycol, which is in your Phase B. It is normal that when you omitted Triethanolamine (TEA) initially, the Ferulic Acid did not dissolve in the water phase. TEA's primary role is to raise the pH (it's a base), not to directly help dissolve Ferulic Acid in water.
• Cause of Cloudiness: When the water phase (Phase A) containing undissolved or partially dissolved Ferulic Acid is mixed with the oil phase (Phase B), the ingredients are not fully compatible or dissolved in their respective phases before mixing, leading to an incomplete dispersion and a cloudy, milk-like appearance. Adding TEA later to an already cloudy mixture may not make it clear because the issue stems from the initial dissolution and improper mixing steps.
• Answer to Question 1: TEA is not a solubilizer for Ferulic Acid in water. Its main role is pH adjustment. The cloudiness that occurred when mixing the water phase (with partially dissolved Ferulic Acid) and the oil phase is due to the incomplete dissolution of Ferulic Acid in the water phase and the subsequent mixing with the oil phase containing components that are not immediately compatible, leading to an unstable dispersion.
• Answer to Question 2: You are correct that Ferulic Acid dissolves well in oil-like solvents such as Ethoxydiglycol. The original formula might have placed Ferulic Acid in the water phase, possibly relying on the presence of TEA and the subsequent mixing with the oil phase containing Ethoxydiglycol to achieve full dissolution in the final mixture. However, based on your experience and C7's advice, dissolving it directly in the phase where it is most soluble (the oil phase with Ethoxydiglycol) is a more reliable approach to ensure it dissolves properly from the start. When you properly dissolve Ferulic Acid in the oil phase (Phase B) containing Ethoxydiglycol and then mix this clear oil phase with the water phase (Phase A), the resulting mixture should become clear or mostly clear, especially after warming and proper mixing, as the Ferulic Acid will be dissolved in the Ethoxydiglycol within the final solution. The cloudiness you observed was likely because the Ferulic Acid wasn't properly dissolved in either phase before or immediately after mixing in your previous attempts.

Xanthan Gum Dispersion and Achieving a Slightly Viscous Clear Gel

• Explanation: Xanthan Gum is a water-soluble thickener, not oil-soluble. Adding Xanthan Gum to the oil phase at 40°C is incorrect. Xanthan Gum needs to hydrate (absorb water and swell) in the water phase to form a gel structure. Adding it to the oil phase will not allow it to hydrate properly, which is why you saw undissolved particles.
• Answer to Question 3: Your method was incorrect. To use Xanthan Gum to create a slightly viscous clear gel, you must add it to the water phase (Phase A). Slowly sprinkle the Xanthan Gum powder onto the water while stirring or using a high-speed mixer to prevent clumping. Alternatively, you can pre-disperse the Xanthan Gum in a small amount of Glycerin or Propylene Glycol from Phase B before adding it to the water phase to help it disperse better. Continue stirring or let the mixture sit for some time (e.g., 15-30 minutes or until fully hydrated) to allow the Xanthan Gum to fully hydrate and thicken the water phase into a slightly viscous, clear or translucent gel.
• Answer to Question 4: Since Xanthan Gum should be dissolved in the water phase, this question is based on an incorrect premise for this ingredient. After you have properly dissolved Xanthan Gum in the water phase to achieve the desired gel consistency, you then combine this water phase (Phase A containing dissolved Xanthan Gum) with the oil phase (Phase B) according to the formulation steps.

Recommended Revised Formulation Procedure

Based on the issues and explanations above, here is a suggested revised procedure:

1. Prepare Phase A (Water Phase):

   • Combine Distilled Water, Panthenol, Lemon Peel Bioferment, and Phenoxyethanol.
   • Slowly add Xanthan Gum to the water phase while stirring vigorously (e.g., using a mini-mixer or whisk) to prevent clumping. Alternatively, you can pre-disperse the Xanthan Gum in a small amount of Glycerin or Propylene Glycol from Phase B before adding it to the water phase to help it disperse without clumping.
   • Continue stirring or let the mixture sit for some time (e.g., 15-30 minutes or until fully hydrated) to allow the Xanthan Gum to fully hydrate and thicken the water phase. You should get a slightly viscous, clear or translucent gel.

2. Prepare Phase B (Oil Phase):

   • Combine Ethoxydiglycol, Propylene Glycol, LipidSoft™ Solve, Glycerin, Laureth-23, d-Alpha Tocopherol, and Ferulic Acid.
   • Gently warm this phase (e.g., to around 40-50°C) and stir until the Ferulic Acid is completely dissolved and the phase is clear.

3. Combine Phases A and B:

   • Once both phases are prepared and clear (Phase A is a thickened gel, Phase B is a clear liquid), slowly add Phase B to Phase A while stirring.
   • Continue stirring until the mixture is uniform. It should be a clear or slightly hazy solution/gel.

4. Add Phase C (L-Ascorbic Acid):

   • Add L-Ascorbic Acid to the combined A+B mixture.
   • Stir until the L-Ascorbic Acid is completely dissolved. This may take some time and vigorous stirring. The solution should become clear and will likely turn pale yellow.

5. Add Phase D (Hyaluronic Acid):

   • Add Hyaluronic Acid Standard and Hyaluronic Acid Nano.
   • Stir or shake until the Hyaluronic Acid powders are fully dispersed. They will take time to hydrate and thicken the solution further. Letting it sit for a few hours or overnight in the refrigerator can help with full hydration.

6. Adjust pH:

   • After all ingredients are dissolved and the mixture is uniform, measure the pH.
   • Slowly add Triethanolamine (TEA) drop by drop or in small increments, stirring well after each addition, until the desired pH (e.g., 3.5-3.7) is reached. Keep track of the total amount of TEA added. You will likely need significantly less than 2.5g to reach this pH range, especially since your original attempt without TEA (but with L-Ascorbic Acid) resulted in pH 4.2. Start with a very small amount (e.g., 0.5g or less) and add gradually.

7. Final Check:

   • Once the desired pH is achieved, ensure the mixture is clear and uniform. Store in an airtight, opaque container to protect from light and air.

By correctly placing Ferulic Acid in the oil phase and Xanthan Gum in the water phase and following the proper hydration steps, you should be able to resolve the cloudiness and texture issues. Adjusting the pH at the final step will also give you more precise control over the final pH value.