Questions about Modified Skinceuticals C E Ferulic Serum Formulation

Hello! Thank you for sharing your modified formula based on the Skinceuticals C E Ferulic serum. It looks like you've incorporated several interesting ingredients.

Regarding your questions:

• You mentioned ingredients that are underlined as additions or quantity changes, but there are no underlines visible in the text provided. Could you clarify which ingredients you were referring to?
• 1. Is this formula okay? Any recommendations?
  The formula appears to be a well-thought-out attempt to combine the classic C E Ferulic antioxidant system with additional ingredients targeting whitening (Lemon peel bioferment, L-glutathione) and hydration/soothing (Panthenol, Hyaluronic Acids). The core combination of 15% L-Ascorbic Acid, 1% Vitamin E, and 0.5% Ferulic Acid is a proven synergistic blend for antioxidant protection. The inclusion of Ethoxydiglycol and Propylene glycol are standard choices for dissolving L-Ascorbic Acid. The addition of other actives seems complementary to the overall goal of an antioxidant and brightening serum. Overall, it looks like a promising formulation approach.
• 2. Will the pH be okay?
  The target pH of 3.5-4 is indeed optimal for the stability and skin penetration of L-Ascorbic Acid. However, simply mixing the ingredients will not guarantee this specific pH. L-Ascorbic Acid is acidic, so the initial pH will likely be low. You will need to measure the pH of the final mixture using a pH meter and adjust it upwards to the 3.5-4 range using Triethanolamine as you mentioned. The ingredients in your formula should allow for successful pH adjustment to this range.
• 3. If we add cyclomethicone, will it work? Will it feel quick-absorbing and comfortable? By substituting ethoxydiglycol : cyclomethicone = 10g:10g?
  Cyclomethicone is a volatile silicone that can indeed provide a smooth, dry, and quick-absorbing feel, contributing to that "disappearing" sensation. However, Cyclomethicone is not miscible with water or the polar solvents like Ethoxydiglycol and Propylene glycol that form the base of your formula. Directly adding Cyclomethicone or substituting it for Ethoxydiglycol as proposed (10g Ethoxydiglycol replaced by 10g Cyclomethicone) will likely cause the formula to separate because Cyclomethicone is incompatible with the main phase. Ethoxydiglycol is also crucial for dissolving the L-Ascorbic Acid. To successfully incorporate Cyclomethicone, you would need to significantly change the formulation structure, likely creating a water-in-silicone emulsion, which would require specific emulsifiers (like those designed for water-in-silicone systems) and would change the product's appearance (it would likely become opaque or cloudy, as mentioned by C7). Therefore, the proposed method of substitution is unlikely to work and would destabilize the formula.

I hope this analysis is helpful for your formulation process!