Formulation Feedback

Regarding your proposed formula with 15% Vitamin C (L-ascorbic acid) (Ultra-Fine), 1% Licorice Extract, 20% Witch Hazel, and the rest water, there is a significant consideration regarding the stability of the Vitamin C.

L-ascorbic acid, particularly in a water-based solution, is highly unstable and prone to oxidation, which reduces its effectiveness. The Ultra-Fine grade is designed for better dispersion but still has low stability when dissolved in water. While a low pH (2.0-4.0, with FDA requiring at least 3.5) is necessary for L-ascorbic acid formulas, the presence of a large amount of water at a high concentration like 15% will likely cause the Vitamin C to degrade quickly.

For water-based serums or lotions, it is generally recommended to use more stable water-soluble Vitamin C derivatives. Some suitable alternatives include:

• Ethyl Ascorbic Acid
• Ascorbyl Glucoside
• Magnesium Ascorbyl Phosphate (MAP)
• Sodium Ascorbyl Phosphate (SAP)

These derivatives offer better stability in water-based formulations while still providing beneficial effects.

Licorice Extract and Witch Hazel are water-soluble and can be incorporated into water-based formulas, provided the overall pH is within their recommended range and suitable for other ingredients.

Therefore, while the combination of ingredients is possible in terms of solubility, the stability of L-ascorbic acid at 15% in a water base is the primary concern for the effectiveness and shelf-life of your product. Consider using a stable Vitamin C derivative for better results in a water-dominant formula.